Abstract:

Quantum Key Distribution (QKD) and Quantum Random Number Generators (QRNG) are the first applications of quantum physics at the level of individual quanta. They emerged from very fundamental research on the foundations of quantum theory, but are nowadays commercially available and clients use them daily, usually obliviously.

Today’s research in QKD and QRNG spans a broad spectrum, from very applied research aiming at developing cheaper, faster and smaller devices, all the way to abstract academic research on the deep connections with quantum non-locality. In between, quantum networks occupy a central place. Several architectures are considered, some based on optical fibers, some on free space communication, including possibly satellites. Long distance quantum networks require repeaters; a first solution consists in using “trusted node repeaters”, a more futuristic and safer solution will exploit quantum teleportation and quantum memories.

Abstract:

Although quantum cryptography is based on beautiful principles, in practice the quality of implementation plays a large role. The advent of hackers in the field has revealed many imperfections and loopholes in first-generation systems. The research and manufacturing community successfully addresses these imperfections by designing better systems and protocols, albeit this process does not happen overnight. A systematic search for remaining security vulnerabilities is currently taking place. We hope that this will eventually lead to development of hacker-proof systems, and to introduction of security certification standards for quantum cryptography equipment.

Abstract:

In this talk, we will present activities in Tokyo QKD network. In the first part, we will introduce our recent long term field test of our QKD system. The second part of the talk will be devoted to theoretical approach to counter-measure side-channel issues of QKD systems, in particular to state preparation flaw in QKD systems. Crucially, the security analyses of most existing QKD experiments simply neglect this effect, and if this effect is taken into account through the well-known theoretical analyses, the key from the QKD systems becomes insecure. We introduce a novel and general approach that makes QKD robust against state preparation flaws. Importantly, it suggests that the state preparation process in QKD can be significantly less precise than initially thought. Our method can widely apply to many quantum cryptographic protocols.

Abstract:

Like BB84 protocol for DVQKD, coherent states protocols are the most studied CVQKD protocols. This is because they can be implemented with standard telecommunication components. In this talk, we present the different steps of GG02 (Grosshans Grangier) coherent states protocol and emphasize performance and security aspects of its practical implementation.

Abstract:

In this lecture I discuss the relativistic correlation function in a bipartite system of two spin one-half massive particles. In particular, the Møller electron pair originating from the e−e− --> e−e− scattering of a polarized electron beam on an unpolarized target is analysed. The presented results might help in experimentally verifying whether relativistic quantum theory is able to reproduce the behaviour of real quantum systems.

Abstract:

NLTK at WUT holds a unique posisiton among similar laboratories by hosting both non-entanglement and entanglement quantum cryptography R&D systems. This enables complementary research of QKD deployment in practical network scenarios (in metropolitan infrastructure) with issues of telecom fibers sharing, decoherence, network topologies and different technologies interoperability. Important direction within NLTK research focuses on extending entanglement based QKD setups into experimental deployment of QSDC protocols. Theoretical work encompasses investigating relation between superdense coding based non-local secure communication and QKD.

Abstract:

The frequency correlation (or decorrelation) of photon pairs is of great importance in long-range quantum communications and photonic quantum computing. We experimentally characterize a spontaneous parametric down conversion (SPDC) source, based on a Beta-Barium Borate (BBO) crystal cut for type-II phase matching at 1550 nm which has the capability to emit photons with positive or no spectral correlations.

Abstract:

Randomness amplification is the task of transforming a source of somewhat random bits into a source of fully random bits. Although it is impossible to amplify randomness from a single source by classical means, the situation is different when considering non-local correlations allowed by quantum mechanics. Here we give the first device-independent protocol for randomness amplification using a constant number of devices. The protocol involves eight devices, can amplify any non-deterministic source into a fully random source, tolerates a constant rate of error, and has its correctness based solely on the assumption of no-signaling between the devices. In contrast, all previous protocols either required an infinite number of devices, or could only amplify sources sufficiently close to fully random.

Abstract:

Contemporary military security of a state heavily depends on efficient protection of information pertaining to military and defence issues in the whole spectrum of organizational and functional structures and decision bodies, from the level of the leadership of the state, defence ministry and armed forces to the troops’ tactical level. Usage of national and unique solutions in the field of cryptographical protection has the key importance for keeping information secure. There was not an institution responsible for overall activities in this area in Polish defence sphere up to 2013. This gap was filled with the creation of the National Centre of Cryptology, a specialized unit within the MOD. It is responsible for a creation of the modern, strictly Polish cryptographical solutions, both software and hardware, in cooperation with Polish universities and research centre as well as with Polish industries.

Abstract:

We present the results of a feasibility study on the application of QKD links to a GNSS network with reference to the Galileo architecture. We derive specifications for an inter-satellite QKD network and evaluate its expected performance in terms of achievable key lengths. In order to allow efficient and secure connections among all satellites, it is desirable that the QKD network has a high degree of connectivity. However the mass and volume limitations on satellite payloads prevent equipping each node with several distinct transceivers. Therefore, a tradeoff must be sought between loading each satellite with the fewest possible transceivers and yet allowing sufficient connection redundancy for reliable, safe and secure QKD in the network. By exploiting the time intervals where two satellites in different orbital planes get closest, sufficient key rates and a high degree of connectivity in the QKD network could be achieved, even if every satellite is equipped with just one telescope and . In fact, the resulting network has four disjoint paths joining any pair of nodes and is thus robust against up to three failing nodes or links, and with respect to one byzantine adversary node.

Abstract:

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This report is devoted to applications of coherent emission of two subgroups of photons, the summer (or difference) energies of which can be regarded as a constant so that coherence appear between the blocs of the product of two electromagnetic field strength. As it was shown recently, spatial-Multimode broadband squeezed light can generate coherent states of the bimodal electromagnetic field observed in photon counting experiment the statistics of which are regular not only in time, but in the plane of observation too. The application of second order space-time coherence of light formed from entangled photons in holography and lithography follows from the definition of the quantum states of such bimodal fields.
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