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  • 1.
    Abellán, C.
    et al.
    ICFO - Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Barcelona, Spain.
    Acín, A.
    ICFO - Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Barcelona, Spain / ICREA - Institució Catalana de Recerca i Estudis Avançats, Barcelona, Spain.
    Alarcón, A.
    Millennium Institute for Research in Optics, Universidad de Concepción, Concepción, Chile; Departamento de Ingeniería Eléctrica, Universidad de Concepción, Concepción, Chile.
    Alibart, O.
    Université Côte d’Azur, CNRS UMR 7010, Institut de Physique de Nice (INPHYNI), Nice, France.
    Andersen, C. K.
    Department of Physics, ETH Zurich, Zurich, Switzerland.
    Andreoli, F.
    Dipartimento di Fisica, Sapienza Università di Roma, Rome, Italy.
    Beckert, A.
    Department of Physics, ETH Zurich,, Zurich, Switzerland.
    Beduini, F. A.
    ICFO - Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Barcelona, Spain.
    Bendersky, A.
    Departamento de Computación, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires; Instituto de Investigación en Ciencias de la Comunicación (ICC), CONICET, Buenos Aires, Argentina.
    Bentivegna, M.
    Dipartimento di Fisica, Sapienza Università di Roma, Rome, Italy.
    Bierhorst, P.
    National Institute of Standards and Technology, Boulder, CO, USA.
    Burchardt, D.
    Ludwig-Maximilians-Universität, Munich, Germany.
    Cabello, A.
    Departamento de Física Aplicada II, Universidad de Sevilla, Seville, Spain.
    Cariñe, J.
    Millennium Institute for Research in Optics, Universidad de Concepción, Universidad de Concepción, Concepción, Chile.
    Carrasco, S.
    ICFO - Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, Barcelona, Spain.
    Carvacho, G.
    Dipartimento di Fisica, Sapienza Università di Roma, Rome, Italy.
    Cavalcanti, D.
    Chaves, R.
    Cortés-Vega, J.
    Cuevas, A.
    Delgado, A.
    de Riedmatten, H.
    Eichler, C.
    Farrera, P.
    Fuenzalida, J.
    García-Matos, M.
    Garthoff, R.
    Gasparinetti, S.
    Gerrits, T.
    Ghafari Jouneghani, F.
    Glancy, S.
    Gómez, E. S.
    González, P.
    Guan, J. -Y.
    Handsteiner, J.
    Heinsoo, J.
    Heintze, G.
    Hirschmann, A.
    Jiménez, O.
    Kaiser, F.
    Knill, E.
    Knoll, L. T.
    Krinner, S.
    Kurpiers, P.
    Larotonda, M. A.
    Larsson, Jan-Åke
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Lenhard, A.
    Li, H.
    Li, M. -H.
    Lima, G.
    Liu, B.
    Liu, Y.
    López Grande, I. H.
    Lunghi, T.
    Ma, X.
    Magaña-Loaiza, O. S.
    Magnard, P.
    Magnoni, A.
    Martí­-Prieto, M.
    Martínez, D.
    Mataloni, P.
    Mattar, A.
    Mazzera, M.
    Mirin, R. P.
    Mitchell, M. W.
    Nam, S.
    Oppliger, M.
    Pan, J. -W.
    Patel, R. B.
    Pryde, G. J.
    Rauch, D.
    Redeker, K.
    Rieländer, D.
    Ringbauer, M.
    Roberson, T.
    Rosenfeld, W.
    Salathé, Y.
    Santodonato, L.
    Sauder, G.
    Scheidl, T.
    Schmiegelow, C. T.
    Sciarrino, F.
    Seri, A.
    Shalm, L. K.
    Shi, S. -C
    Slussarenko, S.
    Stevens, M. J.
    Tanzilli, S.
    Toledo, F.
    Tura, J.
    Ursin, R.
    Vergyris, P.
    Verma, V. B.
    Walter, T.
    Wallraff, A.
    Wang, Z.
    Weinfurter, H.
    Weston, M. M.
    White, A. G.
    Wu, C.
    Xavier, Guilherme B.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    You, L.
    Yuan, X.
    Zeilinger, A.
    Zhang, Q.
    Zhang, W.
    Zhong, J.
    Challenging Local Realism with Human Choices2018In: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 557, p. 212-216Article in journal (Refereed)
    Abstract [en]

    A Bell test is a randomized trial that compares experimental observations against the philosophical worldview of local realism , in which the properties of the physical world are independent of our observation of them and no signal travels faster than light. A Bell test requires spatially distributed entanglement, fast and high-efficiency detection and unpredictable measurement settings. Although technology can satisfy the first two of these requirements, the use of physical devices to choose settings in a Bell test involves making assumptions about the physics that one aims to test. Bell himself noted this weakness in using physical setting choices and argued that human 'free will' could be used rigorously to ensure unpredictability in Bell tests. Here we report a set of local-realism tests using human choices, which avoids assumptions about predictability in physics. We recruited about 100,000 human participants to play an online video game that incentivizes fast, sustained input of unpredictable selections and illustrates Bell-test methodology. The participants generated 97,347,490 binary choices, which were directed via a scalable web platform to 12 laboratories on five continents, where 13 experiments tested local realism using photons, single atoms, atomic ensembles and superconducting devices. Over a 12-hour period on 30 November 2016, participants worldwide provided a sustained data flow of over 1,000 bits per second to the experiments, which used different human-generated data to choose each measurement setting. The observed correlations strongly contradict local realism and other realistic positions in bi-partite and tri-partite 12 scenarios. Project outcomes include closing the 'freedom-of-choice loophole' (the possibility that the setting choices are influenced by 'hidden variables' to correlate with the particle properties), the utilization of video-game methods for rapid collection of human-generated randomness, and the use of networking techniques for global participation in experimental science.

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    Challenging local realism with human choices
  • 2.
    Abidin, Aysajan
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Authentication in Quantum Key Distribution: Security Proof and Universal Hash Functions2013Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Quantum Key Distribution (QKD) is a secret key agreement technique that consists of two parts: quantum transmission and measurement on a quantum channel, and classical post-processing on a public communication channel. It enjoys provable unconditional security provided that the public communication channel is immutable. Otherwise, QKD is vulnerable to a man-in-the-middle attack. Immutable public communication channels, however, do not exist in practice. So we need to use authentication that implements the properties of an immutable channel as well as possible. One scheme that serves this purpose well is the Wegman-Carter authentication (WCA), which is built upon Almost Strongly Universal2 (ASU2) hashing. This scheme uses a new key in each authentication attempt to select a hash function from an ASU2 family, which is then used to generate the authentication tag for a message.

    The main focus of this dissertation is on authentication in the context of QKD. We study ASU2 hash functions, security of QKD that employs a computationally secure authentication, and also security of authentication with a partially known key. Specifically, we study the following.

    First, Universal hash functions and their constructions are reviewed, and as well as a new construction of ASU2 hash functions is presented. Second, security of QKD that employs a specific computationally secure authentication is studied. We present detailed attacks on various practical implementations of QKD that employs this authentication. We also provide countermeasures and prove necessary and sufficient conditions for upgrading the security of the authentication to the level of unconditional security. Third, Universal hash function based multiple authentication is studied. This uses a fixed ASU2 hash function followed by one-time pad encryption, to keep the hash function secret. We show that the one-time pad is necessary in every round for the authentication to be unconditionally secure. Lastly, we study security of the WCA scheme, in the case of a partially known authentication key. Here we prove tight information-theoretic security bounds and also analyse security using witness indistinguishability as used in the Universal Composability framework.

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    Authentication in Quantum Key Distribution: Security Proof and Universal Hash Functions
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    omslag
  • 3.
    Abidin, Aysajan
    Linköping University, Department of Electrical Engineering, Information Coding.
    On Security of Universal Hash Function Based Multiple Authentication2012In: Lecture Notes in Computer Science, Vol. 7618 / [ed] Chim, Tat Wing and Yuen, Tsz Hon, 2012, p. 303-310Conference paper (Refereed)
    Abstract [en]

    Universal hash function based multiple authentication was originally proposed by Wegman and Carter in 1981. In this authentication, a series of messages are authenticated by first hashing each message by a fixed (almost) strongly universal$_2$ hash function and then encrypting the hash value with a preshared one-time pad. This authentication is unconditionally secure. In this paper, we show that the unconditional security cannot be guaranteed if the hash function output for the first message is not encrypted, as remarked in [Atici and Stinson, CRYPTO '96. LNCS, vol. 1109]. This means that it is not only sufficient, but also necessary, to encrypt the hash of every message to be authenticated in order to have unconditional security. The security loss is demonstrated by a simple existential forgery attack.

  • 4.
    Abidin, Aysajan
    et al.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Larsson, Jan-Åke
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Direct proof of security of Wegman-Carter authentication with partially known key2014In: Quantum Information Processing, ISSN 1570-0755, E-ISSN 1573-1332, Vol. 13, no 10, p. 2155-2170Article in journal (Refereed)
    Abstract [en]

    Information-theoretically secure (ITS) authentication is needed in Quantum Key Distribution (QKD). In this paper, we study security of an ITS authentication scheme proposed by Wegman& Carter, in the case of partially known authentication key. This scheme uses a new authentication key in each authentication attempt, to select a hash function from an Almost Strongly Universal2 hash function family. The partial knowledge of the attacker is measured as the trace distance between the authentication key distribution and the uniform distribution; this is the usual measure in QKD. We provide direct proofs of security of the scheme, when using partially known key, first in the information-theoretic setting and then in terms of witness indistinguishability as used in the Universal Composability (UC) framework. We find that if the authentication procedure has a failure probability ε and the authentication key has an ε´ trace distance to the uniform, then under ITS, the adversary’s success probability conditioned on an authentic message-tag pair is only bounded by ε +|Ƭ|ε´, where |Ƭ| is the size of the set of tags. Furthermore, the trace distance between the authentication key distribution and the uniform increases to |Ƭ|ε´ after having seen an authentic message-tag pair. Despite this, we are able to prove directly that the authenticated channel is indistinguishable from an (ideal) authentic channel (the desired functionality), except with probability less than ε + ε´. This proves that the scheme is (ε + ε´)-UC-secure, without using the composability theorem.

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  • 5.
    Abidin, Aysajan
    et al.
    Linköping University, Department of Electrical Engineering, Information Coding.
    Larsson, Jan-Åke
    Linköping University, Department of Electrical Engineering, Information Coding.
    New Universal Hash Functions2012In: Lecture Notes in Computer Science, Vol. 7242 / [ed] Frederik Armknecht and Stefan Lucks, Springer Berlin Heidelberg , 2012, p. 99-108Conference paper (Refereed)
    Abstract [en]

    Universal hash functions are important building blocks for unconditionally secure message authentication codes. In this paper, we present a new construction of a class of Almost Strongly Universal hash functions with much smaller description (or key) length than the Wegman-Carter construction. Unlike some other constructions, our new construction has a very short key length and a security parameter that is independent of the message length, which makes it suitable for authentication in practical applications such as Quantum Cryptography.

  • 6.
    Abidin, Aysajan
    et al.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Pacher, Christoph
    Austrian Institute of Technology, Austria.
    Lorünser, Thomas
    Austrian Institute of Technology, Austria.
    Larsson, Jan-Åke
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Peev, Momtchil
    Austrian Institute of Technology, Austria.
    Quantum cryptography and authentication with low key-consumption2011In: Proceedings of SPIE - The International Society for Optical Engineering, 2011, p. 818916-Conference paper (Refereed)
    Abstract [en]

    Quantum Key Distribution (QKD - also referred to as Quantum Cryptography) is a technique for secret key agreement. It has been shown that QKD rigged with Information-Theoretic Secure (ITS) authentication (using secret key) of the classical messages transmitted during the key distribution protocol is also ITS. Note, QKD without any authentication can trivially be broken by man-in-the-middle attacks. Here, we study an authentication method that was originally proposed because of its low key consumption; a two-step authentication that uses a publicly known hash function, followed by a secret strongly universal2 hash function, which is exchanged each round. This two-step authentication is not information-theoretically secure but it was argued that nevertheless it does not compromise the security of QKD. In the current contribution we study intrinsic weaknesses of this approach under the common assumption that the QKD adversary has access to unlimited resources including quantum memories. We consider one implementation of Quantum Cryptographic protocols that use such authentication and demonstrate an attack that fully extract the secret key. Even including the final key from the protocol in the authentication does not rule out the possibility of these attacks. To rectify the situation, we propose a countermeasure that, while not informationtheoretically secure, restores the need for very large computing power for the attack to work. Finally, we specify conditions that must be satisfied by the two-step authentication in order to restore informationtheoretic security.

  • 7.
    Adamsson, Gustav
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Fast and Approximate Text Rendering Using Distance Fields2015Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Distance field text rendering has many advantages compared to most other text renderingsolutions. Two of the advantages are the possibility  to scale the glyphs without losing the crisp edge and less memory consumption. A drawback with distance field text renderingcan be high distance field generation time. The solution for fast distance field text renderingin this thesis generates the distance fields by drawing distance gradients locally over the outlines of the glyphs. This method is much faster than the old exact methods for generating distance fields that often includes multiple passes over the whole image.

    Using the solution for text rendering proposed in this thesis results in good looking text that is generated on the fly. The distance fields are generated on a mobile device in less than 10 ms for most of the glyphs in good quality which is less than the time between two frames.

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  • 8.
    Aguilar, Edgar A.
    et al.
    Univ Gdansk, Poland.
    Farkas, Mate
    Univ Gdansk, Poland.
    Martinez, Daniel
    Univ Concepcion, Chile.
    Alvarado, Matias
    Univ Concepcion, Chile.
    Carine, Jaime
    Univ Concepcion, Chile.
    Xavier, Guilherme B
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering. Univ Concepcion, Chile.
    Barra, Johanna F.
    Univ Concepcion, Chile.
    Canas, Gustavo
    Univ Bio Bio, Chile.
    Pawlowski, Marcin
    Univ Gdansk, Poland.
    Lima, Gustavo
    Univ Concepcion, Chile.
    Certifying an Irreducible 1024-Dimensional Photonic State Using Refined Dimension Witnesses2018In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 120, no 23, article id 230503Article in journal (Refereed)
    Abstract [en]

    We report on a new class of dimension witnesses, based on quantum random access codes, which are a function of the recorded statistics and that have different bounds for all possible decompositions of a high-dimensional physical system. Thus, it certifies the dimension of the system and has the new distinct feature of identifying whether the high-dimensional system is decomposable in terms of lower dimensional subsystems. To demonstrate the practicability of this technique, we used it to experimentally certify the generation of an irreducible 1024-dimensional photonic quantum state. Therefore, certifying that the state is not multipartite or encoded using noncoupled different degrees of freedom of a single photon. Our protocol should find applications in a broad class of modern quantum information experiments addressing the generation of high-dimensional quantum systems, where quantum tomography may become intractable.

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  • 9.
    Ahlberg, Jörgen
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Visualization Techniques for Surveillance: Visualizing What Cannot Be Seen and Hiding What Should Not Be Seen2015In: Konsthistorisk Tidskrift, ISSN 0023-3609, E-ISSN 1651-2294, Vol. 84, no 2, p. 123-138Article in journal (Refereed)
    Abstract [en]

    This paper gives an introduction to some of the problems of modern camera surveillance, and how these problems are, or can be, addressed using visualization techniques. The paper is written from an engineering point of view, attempting to communicate visualization techniques invented in recent years to the non-engineer reader. Most of these techniques have the purpose of facilitating for the surveillance operator to recognize or detect relevant events (such as violence), while, in contrast, some have the purpose of hiding information in order to be less privacy-intrusive. Furthermore, there are also cameras and sensors that produce data that have no natural visible form, and methods for visualizing such data are discussed as well. Finally, in a concluding discussion an attempt is made to predict how the discussed methods and techniques will be used in the future. 

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  • 10.
    Ahlberg, Jörgen
    et al.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, Faculty of Science & Engineering. Termisk Systemteknik AB, Linköping, Sweden.
    Berg, Amanda
    Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, Faculty of Science & Engineering. Termisk Systemteknik AB, Linköping, Sweden.
    Evaluating Template Rescaling in Short-Term Single-Object Tracking2015Conference paper (Refereed)
    Abstract [en]

    In recent years, short-term single-object tracking has emerged has a popular research topic, as it constitutes the core of more general tracking systems. Many such tracking methods are based on matching a part of the image with a template that is learnt online and represented by, for example, a correlation filter or a distribution field. In order for such a tracker to be able to not only find the position, but also the scale, of the tracked object in the next frame, some kind of scale estimation step is needed. This step is sometimes separate from the position estimation step, but is nevertheless jointly evaluated in de facto benchmarks. However, for practical as well as scientific reasons, the scale estimation step should be evaluated separately – for example,theremightincertainsituationsbeothermethodsmore suitable for the task. In this paper, we describe an evaluation method for scale estimation in template-based short-term single-object tracking, and evaluate two state-of-the-art tracking methods where estimation of scale and position are separable.

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    fulltext
  • 11.
    Ahlberg, Jörgen
    et al.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Li, Haibo
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Representing and Compressing MPEG-4 Facial Animation Parameters using Facial Action Basis Functions1999In: IEEE Transactions on Circuits and Systems, ISSN 0098-4094, E-ISSN 1558-1276, Vol. 9, no 3, p. 405-410Article in journal (Refereed)
    Abstract [en]

    In model-based, or semantic, coding, parameters describing the nonrigid motion of objects, e.g., the mimics of a face, are of crucial interest. The facial animation parameters (FAPs) specified in MPEG-4 compose a very rich set of such parameters, allowing a wide range of facial motion. However, the FAPs are typically correlated and also constrained in their motion due to the physiology of the human face. We seek here to utilize this spatial correlation to achieve efficient compression. As it does not introduce any interframe delay, the method is suitable for interactive applications, e.g., videophone and interactive video, where low delay is a vital issue.

  • 12.
    Ahlberg, Jörgen
    et al.
    Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, Faculty of Science & Engineering.
    Åstrom, Anders
    Swedish Natl Forens Ctr NFC, Linkoping, Sweden.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Simultaneous sensing, readout, and classification on an intensity-ranking image sensor2018In: International journal of circuit theory and applications, ISSN 0098-9886, E-ISSN 1097-007X, Vol. 46, no 9, p. 1606-1619Article in journal (Refereed)
    Abstract [en]

    We combine the near-sensor image processing concept with address-event representation leading to an intensity-ranking image sensor (IRIS) and show the benefits of using this type of sensor for image classification. The functionality of IRIS is to output pixel coordinates (X and Y values) continuously as each pixel has collected a certain number of photons. Thus, the pixel outputs will be automatically intensity ranked. By keeping track of the timing of these events, it is possible to record the full dynamic range of the image. However, in many cases, this is not necessary-the intensity ranking in itself gives the needed information for the task at hand. This paper describes techniques for classification and proposes a particular variant (groves) that fits the IRIS architecture well as it can work on the intensity rankings only. Simulation results using the CIFAR-10 dataset compare the results of the proposed method with the more conventional ferns technique. It is concluded that the simultaneous sensing and classification obtainable with the IRIS sensor yields both fast (shorter than full exposure time) and processing-efficient classification.

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  • 13.
    Ajma, Muhammad
    et al.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Furdek, Marija
    School of Information and Communication Technology, KTH Royal Institute of Technology, Stockholm, Sweden / Faculty of Electrical Engineering and Computing, Dept. of Telecommunications, University of Zagreb, Croatia.
    Monti, Paolo
    School of Information and Communication Technology, KTH Royal Institute of Technology, Stockholm, Sweden.
    Wosinska, Lena
    School of Information and Communication Technology, KTH Royal Institute of Technology, Stockholm, Sweden.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Dynamic provisioning utilizing redundant modules in elastic optical networks based on architecture on demand nodes2014In: European Conference on Optical Communication (ECOC), 2014, IEEE , 2014, p. 1-3Conference paper (Refereed)
    Abstract [en]

    Survivable synthetic ROADMs are equipped with redundant switching modules to support failure recovery. The paper proposes a dynamic connection provisioning strategy which exploits these idle redundant modules to provision regular traffic resulting in a substantial improvement in the blocking performance.

  • 14.
    Ajmal, Muhammad
    et al.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Cavdar, Cicek
    Royal Institute of Technology, KTH, Stockholm, Sweden.
    Wosinska, Lena
    Royal Institute of Technology, KTH, Stockholm, Sweden.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Trading Quality of Transmission for Improved Blocking Performance in All-Optical Networks2013In: Asia Communications and Photonics Conference 2013, 2013, p. AF4E.5-Conference paper (Refereed)
    Abstract [en]

    We propose a connection provisioning strategy in dynamic all-optical networks, which exploit the possibility to allow a tolerable signal quality degradation during a small fraction of holding-time resulting in a significant improvement of blocking performance.

  • 15.
    Ajmal, Muhammad
    et al.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Furdek, Marija
    Royal Institute of Technology, KTH, Stockholm, Sweden / Dept. of Telecommunications, University of Zagreb, Croatia.
    Monti, Paolo
    Royal Institute of Technology, KTH, Stockholm, Sweden.
    Wosinska, Lena
    Royal Institute of Technology, KTH, Stockholm, Sweden.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    An Optimization Model for Dynamic Bulk Provisioning in Elastic Optical Networks2014In: Asia Communications and Photonics Conference 2014, Optics Info Base, Optical Society of America, 2014, p. AF3E.6-Conference paper (Refereed)
    Abstract [en]

    We investigate benefits of setup-delay tolerance in elastic optical networks and propose an optimization model for dynamic and concurrent connection provisioning. Simulation shows that the proposed strategy offers significant improvement of the network blocking performance.

  • 16.
    Ajmal, Muhammad
    et al.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Zervas, Georgios
    High-Performance Networks Group, University of Bristol, UK.
    Saridis, George
    High-Performance Networks Group, University of Bristol, UK.
    Salas, Emilio H.
    High-Performance Networks Group, University of Bristol, UK.
    Simeonidou, Dimitra
    High-Performance Networks Group, University of Bristol, UK.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Flexible and Synthetic SDM Networks with Multi-core-Fibers Implemented by Programmable ROADMs2014In: Proceedings of European Conference on Optical Communication ECOC2014, Cannes, France, September 21-25 September 2014, IEEE , 2014, p. 1-3Conference paper (Refereed)
    Abstract [en]

    This study looks into network planning issues for synthetic MCF-based SDM networks implemented through programmable ROADMs. The results show that significant savings in switching modules and energy can be attained by exploiting the flexibility inherent in programmable ROADM through a proper network design.

  • 17.
    Ajmal, Muhammad
    et al.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Zervas, Georgios
    High-Performance Networks Group, University of Bristol, UK.
    Simeonidou, Dimitra
    High-Performance Networks Group, University of Bristol, UK.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Routing, Spectrum and Core Allocation in Flexgrid SDM Networks with Multi-core Fibers2014In: 2014 INTERNATIONAL CONFERENCE ON OPTICAL NETWORK DESIGN AND MODELING, IEEE , 2014, p. 192-197Conference paper (Refereed)
    Abstract [en]

    Space division multiplexing (SDM) over multi-core fiber (MCF) is advocated as a promising technology to overcome the capacity limit of the current single-core optical networks. However, employing the MCF for flexgrid networks necessitates the development of new concepts, such as routing, spectrum and core allocation (RSCA) for traffic demands. The introduction of MCF in the networks mitigates the spectrum continuity constraint of the routing and spectrum assignment (RSA) problem. In fact cores can be switched freely on different links during routing of the network traffic. Similarly, the route disjointness for demands with same allocated spectrum diminishes to core disjointness at the link level. On the other hand, some new issues such as the inter-core crosstalk should be taken into account while solving the RSCA problem. This paper formulates the RSCA network planning problem using the integer linear programming (ILP) formulation. The aim is to optimally minimize the maximum number of spectrum slices required on any core of MCF of a flexgrid SDM network. Furthermore, a scalable and effective heuristic is proposed for the same problem and its performance is compared with the optimal solution. The results show that the proposed algorithm is able to well approximate the optimal solution based on ILP model.

  • 18.
    Alarcon, Alvaro
    et al.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Argillander, Joakim
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Lima, G.
    Univ Concepcion, Chile; Univ Concepcion, Chile.
    Xavier, Guilherme B
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Few-Mode-Fiber Technology Fine-tunes Losses in Quantum Communication Systems2021In: Physical Review Applied, E-ISSN 2331-7019, Vol. 16, no 3, article id 034018Article in journal (Refereed)
    Abstract [en]

    A natural choice for quantum communication is to use the relative phase between two paths of a single photon for information encoding. This method was nevertheless quickly identified as impractical over long distances, and thus a modification based on single-photon time bins has become widely adopted. It, how-ever, introduces a fundamental loss, which increases with the dimension and limits its application over long distances. Here solve this long-standing hurdle by using a few-mode-fiber space-division-multiplexing platform working with orbital-angular-momentum modes. In our scheme, we maintain the practicability provided by the time-bin scheme, while the quantum states are transmitted through a few-mode fiber in a configuration that does not introduce postselection losses. We experimentally demonstrate our proposal by successfully transmitting phase-encoded single-photon states for quantum cryptography over 500 m of few-mode fiber, showing the feasibility of our scheme.

  • 19.
    Alarcon, Alvaro
    et al.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Argillander, Joakim
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Spegel-Lexne, Daniel
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Xavier, Guilherme B
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Dynamic generation of photonic spatial quantum states with an all-fiber platform2023In: Optics Express, E-ISSN 1094-4087, Vol. 31, no 6, p. 10673-10683Article in journal (Refereed)
    Abstract [en]

    Photonic spatial quantum states are a subject of great interest for applications in quantum communication. One important challenge has been how to dynamically generate these states using only fiber-optical components. Here we propose and experimentally demonstrate an all-fiber system that can dynamically switch between any general transverse spatial qubit state based on linearly polarized modes. Our platform is based on a fast optical switch based on a Sagnac interferometer combined with a photonic lantern and few-mode optical fibers. We show switching times between spatial modes on the order of 5 ns and demonstrate the applicability of our scheme for quantum technologies by demonstrating a measurement-device-independent (MDI) quantum random number generator based on our platform. We run the generator continuously over 15 hours, acquiring over 13.46 Gbits of random numbers, of which we ensure that at least 60.52% are private, following the MDI protocol. Our results show the use of photonic lanterns to dynamically create spatial modes using only fiber components, which due to their robustness and integration capabilities, have important consequences for photonic classical and quantum information processing.(c) 2023 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

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  • 20.
    Alarcon, Alvaro
    et al.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Argillander, Joakim
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Spegel-Lexne, Daniel
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Xavier, Guilherme B.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Quantum Random Number Generation Based on Spatial Modal Superposition over Few-Mode-Fibers2022In: Frontiers in Optics + Laser Science 2022 (FIO, LS), Optica Publishing Group , 2022Conference paper (Refereed)
    Abstract [en]

    A quantum random number generator based on few-mode fiber technology is presented. The randomness originates from measurements of spatial modal quantum superpositions of the LP11a and LP11b modes. The generated sequences have passed NIST tests.

  • 21.
    Alarcon, Alvaro
    et al.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Argillander, Joakim
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Xavier, Guilherme B.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Creating Spatial States of Light for Quantum Information with Photonic Lanterns2021In: Applied Industrial Optics 2021 / [ed] G. Miller, A. Smith, I. Capraro, and J. Majors, Optical Society of America, 2021, article id W2A.2Conference paper (Refereed)
    Abstract [en]

    We demonstrate an all-fiber platform for the generation and detection of spatial photonic states where combinations of LP01, LP11a and LP11b modes are used. This scheme can be employed for quantum communication applications.

  • 22.
    Alarcon, Alvaro
    et al.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Gomez, Santiago
    Univ Concepcion, Chile; Univ Bio Bio, Chile.
    Spegel-Lexne, Daniel
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Argillander, Joakim
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Carine, Jaime
    Univ Catolica Santisima Concepcion, Chile.
    Canas, Gustavo
    Univ Bio Bio, Chile.
    Lima, Gustavo
    Univ Concepcion, Chile; Univ Concepcion, Chile.
    Xavier, Guilherme B
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    All-in-Fiber Dynamically Reconfigurable Orbital Angular Momentum Mode Sorting2023In: ACS Photonics, E-ISSN 2330-4022, Vol. 10, no 10, p. 3700-3707Article in journal (Refereed)
    Abstract [en]

    The orbital angular momentum (OAM) spatial degree of freedom of light has been widely explored in many applications, including telecommunications, quantum information, and light-based micromanipulation. The ability to separate and distinguish between the different transverse spatial modes is called mode sorting or mode demultiplexing, and it is essential to recover the encoded information in such applications. An ideal d mode sorter should be able to faithfully distinguish between the different d spatial modes, with minimal losses, and have d outputs and fast response times. All previous mode sorters rely on bulk optical elements, such as spatial light modulators, which cannot be quickly tuned and have additional losses if they are to be integrated with optical fiber systems. Here, we propose and experimentally demonstrate, to the best of our knowledge, the first all-in-fiber method for OAM mode sorting with ultrafast dynamic reconfigurability. Our scheme first decomposes the OAM mode in-fiber-optical linearly polarized (LP) modes and then interferometrically recombines them to determine the topological charge, thus correctly sorting the OAM mode. In addition, our setup can also be used to perform ultrafast routing of the OAM modes. These results show a novel and fiber-integrated form of optical spatial mode sorting that can be readily used for many new applications in classical and quantum information processing.

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  • 23.
    Alarcon, Alvaro
    et al.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering. Univ Concepcion, Chile.
    Gonzalez, P.
    Univ Concepcion, Chile.
    Carine, J.
    Univ Concepcion, Chile; Univ Catolica Santisima, Chile.
    Lima, G.
    Univ Concepcion, Chile.
    Xavier, Guilherme B
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Polarization-independent single-photon switch based on a fiber-optical Sagnac interferometer for quantum communication networks2020In: Optics Express, E-ISSN 1094-4087, Vol. 28, no 22, p. 33731-33738Article in journal (Refereed)
    Abstract [en]

    An essential component of future quantum networks is an optical switch capable of dynamically routing single photons. Here we implement such a switch, based on a fiber-optical Sagnac interferometer design. The routing is implemented with a pair of fast electro-optical telecom phase modulators placed inside the Sagnac loop, such that each modulator acts on an orthogonal polarization component of the single photons, in order to yield polarization-independent capability that is crucial for several applications. We obtain an average extinction ratio of more than 19 dB between both outputs of the switch. Our experiment is built exclusively with commercial off-the-shelf components, thus allowing direct compatibility with current optical communication systems. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

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  • 24.
    Alarcon, Alvaro
    et al.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Xavier, Guilherme B.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    A few-mode fiber Mach-Zehnder interferometer for quantum communication applications2020In: Frontiers in Optics / Laser Science / [ed] B. Lee, C. Mazzali, K. Corwin, and R. Jason Jones, Optical Society of America, 2020, article id LM1F.6Conference paper (Refereed)
    Abstract [en]

    We show that telecom few-mode fiber Mach-Zehnder interferometers can be used for quantum communication protocols where the LP01 and LP11a modes are employed to encode spatial qubits.

  • 25.
    Alarcón, Alvaro
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    All-Fiber System for Photonic States Carrying Orbital Angular Momentum: A Platform for Classical and Quantum Information Processing2023Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The protection of confidential data is a fundamental need in the society in which we live. This task becomes more relevant when observing that every day, data traffic increases exponentially, as well as the number of attacks on the telecommunication infra-structure. From the natural sciences, it has been strongly argued that quantum communication has great potential to solve this problem, to such an extent that various governmental and industrial entities believe the protection provided by quantum communications will be an important layer in the field of information security in the next decades. However, integrating quantum technologies both in current optical networks and in industrial systems is not a trivial task, taking into account that a large part of current quantum optical systems are based on bulk optical devices, which could become an important limitation. Throughout this thesis we present an all-in-fiber optical platform that allows a wide range of tasks that aim to take a step forward in terms of generation and detection of photonic states. Among the main features, the generation and detection of photonic quantum states carrying orbital angular momentum stand out.   

    The platform can also be configured for the generation of random numbers from quantum mechanical measurements, a central aspect in future information tasks.  

    Our scheme is based on the use of new space-division-multiplexing (SDM) technologies such as few-mode-fibers and photonic lanterns. Furthermore, our platform can also be scaled to high dimensions, it operates in 1550 nm (telecommunications band) and all the components used for its implementation are commercially available. The results presented in this thesis can be a solid alternative to guarantee the compatibility of new SDM technologies in emerging experiments on optical networks and open up new possibilities for quantum communication. 

  • 26.
    Alarcón Cuevas, Alvaro
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    A Few-Mode-Fiber Platform for Quantum Communication Applications2022Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Society as we know it today would not have been possible without the explosive and astonishing development of telecommunications systems, and optical fibers have been one of the pillars of these technologies.

    Despite the enormous amount of data being transmitted over optical networks today, the trend is that the demand for higher bandwidths will also increase. Given this context, a central element in the design of telecommunications networks will be data security, since information can often be confidential or private.

    Quantum information emerges as a solution to encrypt data by quantum key distribution (QKD) between two users. This technique uses the properties of nature as the fundamentals of operation rather than relying on mathematical constructs to provide data protection. A popular alternative to performing QKD is to use the relative phase between two individual photon paths for information encoding. However, this method was not practical over long distances. The time-bin- based scheme was a solution to the previous problem given its practical nature, however, it introduces intrinsic losses due to its design, which increases with the dimension of the encoded quantum system.

    In this thesis we have designed and tested a fiber-optic platform using spatial-division- multiplexing techniques. The use of few-mode fibers and photonic lanterns are the cornerstone of our proposal, which also allow us to support orbital angular momentum (OAM) modes. The platform builds on the core ideas of the phase-coded quantum communication system and also takes advantage of the benefits proposed by the time-bin scheme. We have experimentally tested our proposal by successfully transmitting phase-coded single-photon states over 500 m few-mode fiber, demonstrating the feasibility of our scheme. We demonstrated the successful creation of OAM states, their propagation and their successful detection in an all in-fiber scheme. Our platform eliminates the post-selection losses of time-bin quantum communication systems and ensures compatibility with next-generation optical networks and opens up new possibilities for quantum communication.

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  • 27.
    Ali, Wajid
    et al.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Mohammed, Shahzaan
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Analyzing Wavelength Conversion and Traffic Grooming in Optical WDM Networks2013Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Wavelength conversion and traffic grooming have been among the most researched areas and technologies of importance in optical networking. Network performance improves significantly by relaxing the wavelength continuity constraint using wavelength converters and by improving the wavelength utilization using traffic grooming. We have done a literature review that compares the performance of wavelength conversion devices with different traffic grooming devices. This thesis work analyzes the impact of increasing the number of wavelength conversion devices and grooming capable devices using different placement schemes for our proposed network model, traffic loads and link capacities. Deciding the number and location of these devices to be used in a network is equally important. This work has been done through the simulation of different device placement scenarios and the results have been analyzed using connection blocking probability as the performance metric. Our reviews and work, correctly predict the behavior of results as demonstrated by the results of other referred literatures relating to wavelength conversion and traffic grooming.

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  • 28.
    Almér, Louise
    Linköping University, Department of Electrical Engineering, Information Coding.
    Evaluation of the Perceived Speech Quality for G729D and Opus: With Different Network Scenarios and an Implemented VoIP Application2022Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Communication has always been a vital part of our society, and day-to-day communication is increasingly becoming more digital. VoIP (voice over IP) is used for real-time communication, and to be able to send the information over the internet must the speech be compressed to lower the number of bits needed for transmission. Codecs are used to compress the speech, or any other type of data transmitting over a network, which can introduce some noise if lossy compression is used. Depending on the bandwidth, bit rate, and codec used can distortion be minimized which would result in higher perceived speech quality.

    In the thesis, two codecs, G729D and Opus, were tested and evaluated with two different objective perceive speech quality metrics, POLQA and PESQ. The codecs were also tested with different emulated network scenarios, 2G, 3G, 4G, satellite two-hop, and LAN. Furthermore, Opus was tested with and without VAD (voice activity detection) to see how VAD could affect the perceived speech quality. The different network scenarios did not impact the results of the evaluation, since the main difference between the network scenarios was latency, which POLQA and PESQ do not consider in the evaluation. Opus achieved a higher MOS-LQO (mean opinion score listening quality objective) than G729D. However, when VAD was enabled with Opus for a low bit rate, 8 kbit/s, the MOS-LQO was lower than without VAD. 

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  • 29.
    Alvbrant, Joakim
    et al.
    Linköping University, Department of Electrical Engineering. Linköping University, Faculty of Science & Engineering.
    Keshmiri, Vahid
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Wikner, Jacob
    Linköping University, Department of Electrical Engineering, Integrated Circuits and Systems. Linköping University, Faculty of Science & Engineering.
    Transfer Characteristics and Bandwidth Limitation in a Linear-Drift Memristor Model2015In: 2015 EUROPEAN CONFERENCE ON CIRCUIT THEORY AND DESIGN (ECCTD), IEEE , 2015, p. 332-335Conference paper (Refereed)
    Abstract [en]

    The linear-drift memristor model, suggested by HP Labs a few years ago, is used in this work together with two window functions. From the equations describing the memristor model, the transfer characteristics of a memristor is formulated and analyzed. A first-order estimation of the cut-off frequency is shown, that illustrates the bandwidth limitation of the memristor and how it varies with some of its physical parameters. The design space is elaborated upon and it is shown that the state speed, the variation of the doped and undoped regions of the memristor, is inversely proportional to the physical length, and depth of the device. The transfer characteristics is simulated for Joglekar-Wolf, and Biolek window functions and the results are analyzed. The Joglekar-Wolf window function causes a distinct behavior in the tranfer characteristics at cut-off frequency. The Biolek window function on the other hand gives a smooth state transfer function, at the cost of loosing the one-to-one mapping between charge and state. We also elaborate on the design constraints derived from the transfer characteristics.

  • 30.
    Alvila, Markus
    Linköping University, Department of Electrical Engineering, Information Coding.
    A Performance Evaluation of Post-Quantum Cryptography in the Signal Protocol2019Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The Signal protocol can be considered state-of-the-art when it comes to secure messaging, but advances in quantum computing stress the importance of finding post-quantum resistant alternatives to its asymmetric cryptographic primitives.

    The aim is to determine whether existing post-quantum cryptography can be used as a drop-in replacement for the public-key cryptography currently used in the Signal protocol and what the performance trade-offs may be.

    An implementation of the Signal protocol using commutative supersingular isogeny Diffie-Hellman (CSIDH) key exchange operations in place of elliptic-curve Diffie-Hellman (ECDH) is proposed. The benchmark results on a Samsung Galaxy Note 8 mobile device equipped with a 64-bit Samsung Exynos 9 (8895) octa-core CPU shows that it takes roughly 8 seconds to initialize a session using CSIDH-512 and over 40 seconds using CSIDH-1024, without platform specific optimization.

    To the best of our knowledge, the proposed implementation is the first post-quantum resistant Signal protocol implementation and the first evaluation of using CSIDH as a drop-in replacement for ECDH in a communication protocol.

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    A Performance Evaluation of Post-Quantum Cryptography in the Signal Protocol
  • 31.
    Alwan, Abdulrahman
    Linköping University, Department of Electrical Engineering, Information Coding.
    Implementation of Wavelet-Kalman Filtering Technique for Auditory Brainstem Response2012Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Auditory brainstem response (ABR) evaluation has been one of the most reliable methods for evaluating hearing loss. Clinically available methods for ABR tests require averaging for a large number of sweeps (~1000-2000) in order to obtain a meaningful ABR signal, which is time consuming.  This study proposes a faster new method for ABR filtering based on wavelet-Kalman filter that is able to produce a meaningful ABR signal with less than 500 sweeps. The method is validated against ABR data acquired from 7 normal hearing subjects with different stimulus intensity levels, the lowest being 30 dB NHL. The proposed method was able to filter and produce a readable ABR signal using 400 sweeps; other ABR signal criteria were also presented to validate the performance of the proposed method.

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  • 32.
    Ambuluri, Sreehari
    et al.
    Linköping University, Department of Electrical Engineering. Linköping University, Faculty of Science & Engineering.
    Garrido, Mario
    Linköping University, Department of Electrical Engineering, Electronics System. Linköping University, The Institute of Technology.
    Caffarena, Gabriel
    Boadilla del Monte, Madrid, Spain.
    Ogniewski, Jens
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Ragnemalm, Ingemar
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    New Radix-2 and Radix-22 Constant Geometry Fast Fourier Transform Algorithms For GPUs2013Conference paper (Refereed)
    Abstract [en]

    This paper presents new radix-2 and radix-22 constant geometry fast Fourier transform (FFT) algorithms for graphics processing units (GPUs). The algorithms combine the use of constant geometry with special scheduling of operations and distribution among the cores. Performance tests on current GPUs show a significant improvements compared to the most recent version of NVIDIA’s well-known CUFFT, achieving speedups of up to 5.6x.

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  • 33.
    Amselem, E.
    et al.
    Department of Physics, Stockholm University, Sweden .
    Bourennane, M.
    Department of Physics, Stockholm University, Stockholm University, Sweden .
    Budroni, C.
    Naturwissenschaftlich-Technische Fakultät, Universität Siegen, Germany .
    Cabello, A.
    Departamento de Física Aplicada II, Universidad de Sevilla, Spain .
    Guehne, O.
    Naturwissenschaftlich-Technische Fakultät, Universität Siegen, Germany .
    Kleinmann, M.
    Naturwissenschaftlich-Technische Fakultät, Universität Siegen, Germany .
    Larsson, Jan-Åke
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Wiesniak, M.
    Institute of Theoretical Physics and Astrophysics, University of Gdańsk, Poland .
    Editorial Material: Comment on "State-Independent Experimental Test of Quantum Contextuality"2013In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 110, no 7, p. 1-1Article in journal (Other academic)
    Abstract [en]

    In this Comment we argue that the experiment describedin the recent Letter does not allow one to make con-clusions about contextuality. Our main criticism is that themeasurement of the observables as well as the preparationof the state manifestly depend on the chosen context.Contrary to that, contextuality is about the behavior ofthesamemeasurement device in different experimentalcontexts.

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    Comment on "State-Independent Experimental Test of Quantum Contextuality
  • 34.
    Anders, Åström
    et al.
    Combitech AB, Linköping, Sweden .
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    A High Speed 2D Time-to-Impact Algorithm Targeted for Smart Image Sensors2014In: Proc. SPIE 9022, Image Sensors and Imaging Systems 2014, International Society for Optical Engineering; 1999 , 2014, Vol. 9022Conference paper (Refereed)
    Abstract [en]

    In this paper we present a 2D extension of a previously described 1D method for a time-to-impact sensor [5][6]. As in the earlier paper, the approach is based on measuring time instead of the apparent motion of points in the image plane to obtain data similar to the optical flow. The specific properties of the motion field in the time-to-impact application are used, such as using simple feature points which are tracked from frame to frame. Compared to the 1D case, the features will be proportionally fewer which will affect the quality of the estimation. We give a proposal on how to solve this problem. Results obtained are as promising as those obtained from the 1D sensor.

  • 35.
    Andersson, Andreas
    Linköping University, Department of Electrical Engineering, Information Coding.
    State and Process Tomography: In Spekkens' Toy Model2020Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In 2004 Robert W. Spekkens introduced a toy theory designed to make a case for the epistemic view of quantum mechanics. But how does Spekkens’ toy model differ from quantum theory? While some differences are well-established, we attempt to approach this question from a tomographic point of view. More specifically, we provide experimentally viableprocedureswhichenablesustocompletelycharacterizethestatesandgatesthatare available in the toy model. We show that, in contrast to quantum theory, decompositions of transformations in the toy model must be done in a non-linear fashion.

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  • 36.
    Andersson Ersman, Peter
    et al.
    RISE Acreo, Sweden.
    Lassnig, Roman
    RISE Acreo, Sweden.
    Strandberg, Jan
    RISE Acreo, Sweden.
    Tu, Deyu
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Keshmiri, Vahid
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Fabiano, Simone
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Gustafsson, Goran
    RISE Acreo, Sweden.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    All-printed large-scale integrated circuits based on organic electrochemical transistors2019In: Nature Communications, E-ISSN 2041-1723, Vol. 10, article id 5053Article in journal (Refereed)
    Abstract [en]

    The communication outposts of the emerging Internet of Things are embodied by ordinary items, which desirably include all-printed flexible sensors, actuators, displays and akin organic electronic interface devices in combination with silicon-based digital signal processing and communication technologies. However, hybrid integration of smart electronic labels is partly hampered due to a lack of technology that (de)multiplex signals between silicon chips and printed electronic devices. Here, we report all-printed 4-to-7 decoders and seven-bit shift registers, including over 100 organic electrochemical transistors each, thus minimizing the number of terminals required to drive monolithically integrated all-printed electrochromic displays. These relatively advanced circuits are enabled by a reduction of the transistor footprint, an effort which includes several further developments of materials and screen printing processes. Our findings demonstrate that digital circuits based on organic electrochemical transistors (OECTs) provide a unique bridge between all-printed organic electronics (OEs) and low-cost silicon chip technology for Internet of Things applications.

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  • 37.
    Andersson Ersman, Peter
    et al.
    RISE Acreo AB, Dept Printed Elect, Norrköping, Sweden.
    Westerberg, David
    RISE Acreo AB, Dept Printed Elect, Norrköping, Sweden.
    Tu, Deyu
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Nilsson, Marie
    RISE Acreo AB, Dept Printed Elect, Norrköping, Sweden.
    Åhlin, Jessica
    RISE Acreo AB, Dept Printed Elect, Norrköping, Sweden.
    Eveborn, Annelie
    RISE Acreo AB, Dept Printed Elect, Norrköping, Sweden.
    Lagerlöf, Axel
    RISE Acreo AB, Dept Printed Elect, Norrköping, Sweden.
    Nilsson, David
    RISE Acreo AB, Dept Printed Elect, Norrköping, Sweden.
    Sandberg, Mats
    RISE Acreo AB, Dept Printed Elect, Norrköping, Sweden.
    Norberg, Petronella
    RISE Acreo AB, Dept Printed Elect, Norrköping, Sweden.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering. RISE SICS East, Sweden.
    Gustafsson, Göran
    RISE Acreo AB, Dept Printed Elect, Norrköping, Sweden.
    Screen printed digital circuits based on vertical organic electrochemical transistors2017In: Flexible and Printed Electronics, ISSN 2058-8585, Vol. 2, no 4, article id 045008Article in journal (Refereed)
    Abstract [en]

    Vertical organic electrochemical transistors (OECTs) have been manufactured solely using screen printing. The OECTs are based on PEDOT:PSS (poly(3,4-ethylenedioxythiophene) doped with poly (styrene sulfonic acid)), which defines the active material for both the transistor channel and the gate electrode. The resulting vertical OECT devices and circuits exhibit low-voltage operation, relatively fast switching, small footprint and high manufacturing yield; the last three parameters are explained by the reliance of the transistor configuration on a robust structure in which the electrolyte vertically bridges the bottom channel and the top gate electrode. Two different architectures of the vertical OECT have been manufactured, characterized and evaluated in parallel throughout this report. In addition to the experimental work, SPICE models enabling simulations of standalone OECTs and OECT-based circuits have been developed. Our findings may pave the way for fully integrated, low-voltage operating and printed signal processing systems integrated with e.g. printed batteries, solar cells, sensors and communication interfaces. Such technology can then serve a low-cost base technology for the internet of things, smart packaging and home diagnostics applications.

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  • 38.
    Andersson Ersman, Peter
    et al.
    RISE Acreo, Department of Printed Electronics, Bredgatan 33, Norrköping, SE-602 21, Sweden.
    Zabihipour, Marzieh
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Tu, Deyu
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Lassnig, Roman
    RISE Acreo, Department of Printed Electronics, Bredgatan 33, Norrköping, SE-602 21, Sweden.
    Strandberg, Jan
    RISE Acreo, Department of Printed Electronics, Bredgatan 33, Norrköping, SE-602 21, Sweden.
    Åhlin, Jessica
    RISE Acreo, Department of Printed Electronics, Bredgatan 33, Norrköping, SE-602 21, Sweden.
    Nilsson, Marie
    RISE Acreo, Department of Printed Electronics, Bredgatan 33, Norrköping, SE-602 21, Sweden.
    Westerberg, David
    RISE Acreo, Department of Printed Electronics, Bredgatan 33, Norrköping, SE-602 21, Sweden.
    Gustafsson, Göran
    RISE Acreo, Department of Printed Electronics, Bredgatan 33, Norrköping, SE-602 21, Sweden.
    Berggren, Magnus
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Fabiano, Simone
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Monolithic integration of display driver circuits and displays manufactured by screen printing2020In: Flexible and Printed Electronics, ISSN 2058-8585, Vol. 5, no 2, article id 024001Article in journal (Refereed)
    Abstract [en]

    Here, we report all-screen printed display driver circuits, based on organic electrochemical transistors (OECTs), and their monolithic integration with organic electrochromic displays (OECDs). Both OECTs and OECDs operate at low voltages and have similar device architectures, and, notably, they rely on the very same electroactive material as well as on the same electrochemical switching mechanism. This then allows us to manufacture OECT-OECD circuits in a concurrent manufacturing process entirely based on screen printing methods. By taking advantage of the high current throughput capability of OECTs, we further demonstrate their ability to control the light emission in traditional light-emitting diodes (LEDs), where the actual LED addressing is achieved by an OECT-based decoder circuit. The possibility to monolithically integrate all-screen printed OECTs and OECDs on flexible plastic foils paves the way for distributed smart sensor labels and similar Internet of Things applications. 

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  • 39.
    Andersson Hultgren, Jonas
    Linköping University, Department of Electrical Engineering, Information Coding.
    Metoder för förbättrad rumsuppfattning i körsimulatorer2011Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Today, driving simulators are a very important resource for conducting studies whichconcern driver behavior and perception. Full control of the scenario andenvironment, costs and safety are all factors which makes simulator studiespreferable over real world studies.

    One issue for driving simulators is that the image is projected onto a twodimensionalscreen, which limits the driver's ability to correctly estimate distanceand speed. It is commonly known that distance and velocity are underestimated indriving simulators.

    The goal of this thesis was to find methods that could lead to better distanceestimation in driving simulators and in this project motion parallax and shadowswere implemented and tested, focusing mainly on the former.At the end of the project, a simulator study was conducted to evaluate the effect ofmotion parallax. Ten participants made two runs each in VTI's Simulator III facility,one with motion parallax enabled and one with it disabled. The scenario that tookplace during the two runs consisted of several overtaking situations and a speedperception test.

    The results from the simulator study showed that the participants tended to positionthemselves farther from the road center line when motion parallax was active insituations when the field of view was obscured by preceding vehicles.

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    FULLTEXT02
  • 40.
    Andersson, Martin
    Linköping University, Department of Electrical Engineering, Information Coding.
    Parametric Prediction Model for Perceived Voice Quality in Secure VoIP2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    More and more sensitive information is communicated digitally and with thatcomes the demand for security and privacy on the services being used. An accurateQoS metric for these services are of interest both for the customer and theservice provider. This thesis has investigated the impact of different parameterson the perceived voice quality for encrypted VoIP using a PESQ score as referencevalue. Based on this investigation a parametric prediction model has been developedwhich outputs a R-value, comparable to that of the widely used E-modelfrom ITU. This thesis can further be seen as a template for how to construct modelsof other equipments or codecs than those evaluated here since they effect theresult but are hard to parametrise.

    The results of the investigation are consistent with previous studies regarding theimpact of packet loss, the impact of jitter is shown to be significant over 40 ms.The results from three different packetizers are presented which illustrates theneed to take such aspects into consideration when constructing a model to predictvoice quality. The model derived from the investigation performs well withno mean error and a standard deviation of the error of a mere 1:45 R-value unitswhen validated in conditions to be expected in GSM networks. When validatedagainst an emulated 3G network the standard deviation is even lower.v

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    Thesis_Martin_Andersson
  • 41.
    Appleby, D. M.
    et al.
    Perimeter Institute for Theoretical Physics, Waterloo, Ontario, Canada.
    Bengtsson, Ingemar
    Stockholms Universitet, AlbaNova, Fysikum, Stockholm, Sweden.
    Brierley, Stephen
    Department of Mathematics, University of Bristol, UK.
    Grassl, Markus
    Centre for Quantum Technologies, National University of Singapore, Singapore.
    Gross, David
    Institute for Theoretical Physics, ETH Zürich, 8093 Züurich, Switzerland.
    Larsson, Jan-Åke
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    The monomial representations of the Clifford group2012In: Quantum information & computation, ISSN 1533-7146, Vol. 12, no 5-6, p. 404-431Article in journal (Refereed)
    Abstract [en]

    We show that the Clifford group-the normaliser of the Weyl-Heisenberg group-can be represented by monomial phase-permutation matrices if and only if the dimension is a square number. This simplifies expressions for SIC vectors, and has other applications to SICs and to Mutually Unbiased Bases. Exact solutions for SICs in dimension 16 are presented for the first time.

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    The monomial representations of the Clifford group
  • 42.
    Appleby, D.M.
    et al.
    Perimeter Institute for Theoretical Physics, Waterloo, Ontario, Canada.
    Bengtsson, Ingemar
    Stockholms Universitet, AlbaNova, Fysikum, Stockholm, Sweden.
    Brierley, Stephen
    Heilbronn Institute for Mathematical Research, Department of Mathematics, University of Bristol, United Kingdom.
    Ericsson, Åsa
    Linköping University, Department of Mathematics, Mathematics and Applied Mathematics. Linköping University, The Institute of Technology.
    Grassl, Markus
    Centre for Quantum Technologies, National University of Singapore, Singapore.
    Larsson, Jan-Åke
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Systems of Imprimitivity for the Clifford Group2014In: Quantum information & computation, ISSN 1533-7146, Vol. 14, no 3-4, p. 339-360Article in journal (Refereed)
    Abstract [en]

    It is known that if the dimension is a perfect square the Clifford group can be represented by monomial matrices. Another way of expressing this result is to say that when the dimension is a perfect square the standard representation of the Clifford group has a system of imprimitivity consisting of one dimensional subspaces. We generalize this result to the case of an arbitrary dimension. Let k be the square-free part of the dimension. Then we show that the standard representation of the Clifford group has a system of imprimitivity consisting of k-dimensional subspaces. To illustrate the use of this result we apply it to the calculation of SIC-POVMs (symmetric informationally complete positive operator valued measures), constructing exact solutions in dimensions 8 (hand-calculation) as well as 12 and 28 (machine-calculation).

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  • 43.
    Arbring, Joel
    et al.
    Linköping University, Department of Electrical Engineering, Information Coding.
    Hedström, Patrik
    Linköping University, Department of Electrical Engineering, Information Coding.
    On Data Compression for TDOA Localization2010Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This master thesis investigates different approaches to data compression on common types of signals in the context of localization by estimating time difference of arrival (TDOA). The thesis includes evaluation of the compression schemes using recorded data, collected as part of the thesis work. This evaluation shows that compression is possible while preserving localization accuracy.

    The recorded data is backed up with more extensive simulations using a free space propagation model without attenuation. The signals investigated are flat spectrum signals, signals using phase-shift keying and single side band speech signals. Signals with low bandwidth are given precedence over high bandwidth signals, since they require more data in order to get an accurate localization estimate.

    The compression methods used are transform based schemes. The transforms utilized are the Karhunen-Loéve transform and the discrete Fourier transform. Different approaches for quantization of the transform components are examined, one of them being zonal sampling.

    Localization is performed in the Fourier domain by calculating the steered response power from the cross-spectral density matrix. The simulations are performed in Matlab using three recording nodes in a symmetrical geometry.

    The performance of localization accuracy is compared with the Cramér-Rao bound for flat spectrum signals using the standard deviation of the localization error from the compressed signals.

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    FULLTEXT01
  • 44.
    Argillander, Joakim
    Linköping University, Department of Electrical Engineering, Information Coding.
    Active Phase Compensation in a Fiber-Optical Mach-Zehnder Interferometer2020Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis investigates the phenomena of phase stability in a fiber-optical MZI (Mach-Zehnder Interferometer). The MZI is a key building block of optical systems for use in experiments with both continuous-wave light and with single photons. By splitting incoming light into two beams and allowing it to interfere with itself, an interference pattern is visible at the output, and this phenomena can be used to code information. This is the operating principle in, for example, QKD (Quantum Key Distribution) experiments. This interference requires coherence that is higher than the length difference between the beams that the incoming light is split into. Particularly the phase of the beams must be equal to achieve constructive interference. If one beam is phase-shifted (with respect to the other) due to the light having traversed a longer path, only partially constructive interference is achieved. If the phase shift also varies with time this leads to a system where experiments can no longer reliably be performed. Sources of these fluctuations are thermal, acoustic or mechanical. Fiber-optical interferometers are particularly sensitive to path length fluctuations of the waveguides as the fiber-optic medium contracts and elongates with temperature, and also has a larger surface area for circulating air to mechanically disturb the waveguides than bulk optics interferometers.

    In this thesis, a solution to environment-induced phase drift is presented by evaluating implementations of feedback algorithms for automatic control. The algorithms PID (Proportional-, Integral-, Derivative controller) and an ICA (IncrementalControl Algorithm) have been investigated and the performance of these controllers has been compared when used with, and without, optical enclosures. The algorithms are implemented in an FPGA (Field-Programmable Gate Array) and the controller actuates an electro-optical phase modulator that can add a phase shift to one of the light beams in the MZI. This thesis shows that significant improvement in the optical stability can be achieved with active control compared to an interferometer without active phase control.

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  • 45.
    Argillander, Joakim
    et al.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Alarcon, Alvaro
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Bao, Chunxiong
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering. Nanjing Univ, Peoples R China.
    Kuang, Chaoyang
    Linköping University, Faculty of Science & Engineering. Linköping University, Department of Science and Technology, Laboratory of Organic Electronics.
    Lima, Gustavo
    Univ Concepcion, Chile.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Xavier, Guilherme B.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Quantum random number generation based on a perovskite light emitting diode2023In: Communications Physics, E-ISSN 2399-3650, Vol. 6, no 1, article id 157Article in journal (Refereed)
    Abstract [en]

    True random number generation is not thought to be possible using a classical approach but by instead exploiting quantum mechanics genuine randomness can be achieved. Here, the authors demonstrate a certified quantum random number generation using a metal-halide perovskite light emitting diode as a source of weak coherent polarisation states randomly producing an output of either 0 or 1. The recent development of perovskite light emitting diodes (PeLEDs) has the potential to revolutionize the fields of optical communication and lighting devices, due to their simplicity of fabrication and outstanding optical properties. Here we demonstrate that PeLEDs can also be used in the field of quantum technologies by implementing a highly-secure quantum random number generator (QRNG). Modern QRNGs that certify their privacy are posed to replace classical random number generators in applications such as encryption and gambling, and therefore need to be cheap, fast and with integration capabilities. Using a compact metal-halide PeLED source, we generate random numbers, which are certified to be secure against an eavesdropper, following the quantum measurement-device-independent scenario. The obtained generation rate of more than 10 Mbit s(-1), which is already comparable to commercial devices, shows that PeLEDs can work as high-quality light sources for quantum information tasks, thus opening up future applications in quantum technologies.

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  • 46.
    Argillander, Joakim
    et al.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Alarcon, Alvaro
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Bao, Chunxiong
    Nanjing Univ, Peoples R China.
    Kuang, Chaoyang
    Linköping University, Department of Science and Technology, Laboratory of Organic Electronics. Linköping University, Faculty of Science & Engineering.
    Lima, Gustavo
    Univ Concepcion, Chile; Millennium Inst Res Opt, Chile.
    Gao, Feng
    Linköping University, Department of Physics, Chemistry and Biology, Electronic and photonic materials. Linköping University, Faculty of Science & Engineering.
    Xavier, Guilherme B
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Secure quantum random number generation with perovskite photonics2024In: QUANTUM COMPUTING, COMMUNICATION, AND SIMULATION IV, SPIE-INT SOC OPTICAL ENGINEERING , 2024, Vol. 12911, article id 129111BConference paper (Refereed)
    Abstract [en]

    In the field of cryptography, it is crucial that the random numbers used in key generation are not only genuinely random but also private, meaning that no other party than the legitimate user must have information about the numbers generated. Quantum random number generators can offer both properties - fundamentally random output, as well as the ability to implement generators that can certify the amount of private randomness generated, in order to remove some side-channel attacks. In this study we introduce perovskite technology as a resilient platform for photonics, where the resilience is owed to perovskite's ease of manufacturing. This has the potential to mitigate disruptions in the supply chain by enabling local and domestic manufacturing of photonic devices. We demonstrate the feasibility of the platform by implementing a measurement-device independent quantum random number generator based on perovskite LEDs.

  • 47.
    Argillander, Joakim
    et al.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Alarcon, Alvaro
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Xavier, Guilherme B.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    A tunable quantum random number generator based on a fiber-optical Sagnac interferometer2022In: Journal of Optics, ISSN 2040-8978, E-ISSN 2040-8986, Vol. 24, no 6, article id 064010Article in journal (Refereed)
    Abstract [en]

    Quantum random number generators (QRNGs) are based on naturally random measurementresults performed on individual quantum systems. Here, we demonstrate a branching-pathphotonic QRNG implemented using a Sagnac interferometer with a tunable splitting ratio. Thefine-tuning of the splitting ratio allows us to maximize the entropy of the generated sequence ofrandom numbers and effectively compensate for tolerances in the components. By producingsingle-photons from attenuated telecom laser pulses, and employing commercially-availablecomponents we are able to generate a sequence of more than 2 gigabytes of random numberswith an average entropy of 7.99 bits/byte directly from the raw measured data. Furthermore, oursequence passes randomness tests from both the NIST and Dieharder statistical test suites, thuscertifying its randomness. Our scheme shows an alternative design of QRNGs based on thedynamic adjustment of the uniformity of the produced random sequence, which is relevant forthe construction of modern generators that rely on independent real-time testing of itsperformance.

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  • 48.
    Argillander, Joakim
    et al.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Alarcon, Alvaro
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Xavier, Guilherme B.
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    All-fiber Dynamically Tunable Beamsplitter for Quantum Random Number Generators2022In: Latin America Optics and Photonics Conference / [ed] Optica Publishing Group, Optica Publishing Group , 2022Conference paper (Refereed)
    Abstract [en]

    In this work we demonstrate an all-fiber dynamically tunable beamsplitter based on a Sagnac interferometer capable of realizing measurement-device independent protocols for certifying the privacy of the generated sequence.

  • 49.
    Astrom, Anders
    et al.
    Combitech AB, Linköping, Sweden .
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.
    Low-complexity, high-speed, and high-dynamic range time-to-impact algorithm2012In: Journal of Electronic Imaging (JEI), ISSN 1017-9909, E-ISSN 1560-229X, Vol. 21, no 4Article in journal (Refereed)
    Abstract [en]

    We present a method suitable for a time-to-impact sensor. Inspired by the seemingly "low" complexity of small insects, we propose a new approach to optical flow estimation that is the key component in time-to-impact estimation. The approach is based on measuring time instead of the apparent motion of points in the image plane. The specific properties of the motion field in the time-to-impact application are used, such as measuring only along a one-dimensional (1-D) line and using simple feature points, which are tracked from frame to frame. The method lends itself readily to be implemented in a parallel processor with an analog front-end. Such a processing concept [near-sensor image processing (NSIP)] was described for the first time in 1983. In this device, an optical sensor array and a low-level processing unit are tightly integrated into a hybrid analog-digital device. The high dynamic range, which is a key feature of NSIP, is used to extract the feature points. The output from the device consists of a few parameters, which will give the time-to-impact as well as possible transversal speed for off-centered viewing. Performance and complexity aspects of the implementation are discussed, indicating that time-to-impact data can be achieved at a rate of 10 kHz with todays technology.

  • 50.
    Astrom, Anders
    et al.
    Swedish Natl Forens Ctr, Linkoping, Sweden.
    Forchheimer, Robert
    Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, Faculty of Science & Engineering.
    Statistical approach to time-to-impact estimation suitable for real-time near-sensor implementation2022In: Journal of Electronic Imaging (JEI), ISSN 1017-9909, E-ISSN 1560-229X, Vol. 31, no 6, article id 063023Article in journal (Refereed)
    Abstract [en]

    We present a method to estimate the time-to-impact (TTI) from a sequence of images. The method is based on detecting and tracking local extremal points. Their endurance within and between pixels is measured, accumulated, and used to achieve the TTI. This method, which improves on an earlier proposal, is entirely different from the ordinary optical flow technique and allows for fast and low-complex processing. The method is inspired by insects, which have some TTI capability without the possibility to compute high-complex optical flow. The method is further suitable for near-sensor image processing architectures. (c) The Authors. Published by SPIE under a Creative Commons Attribution 4.0 International License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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