Advanced Quantum Communications Experiments with Entangled Photons

Aspelmeyer, Markus; Zeilinger, Anton; Böhm, Hannes R.; Fedrizzi, Alessandro; Gasparoni, Sara; Lindenthal, M.; Molina‐Terriza, Gabriel; Poppe, Andreas; Resch, Katharina; Ursin, Rupert; Walther, Philip; Jennewein, Thomas

doi:10.1201/9781420026603.ch3

Cited by 4 publications

(12 citation statements)

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“…We say that the quantum operation  in the above diagram is of type  A B. When system A is trivial-that is,when its Hilbert space is one-dimensional-the quantum operation  corresponds to the preparation of a state of system B, diagrammatically represented as When system B is trivial, the quantum operation  in equation (1) corresponds to a measurement effect on system A and is represented as Measurement effects are positive (semidefinite) operators P satisfying  P I , where I is the identity operator on the systemʼs Hilbert space. Effects are associated to the outcomes of measurements and the probability of the outcome corresponding to the effect P is given by the Born rule ð2Þ where ρ is the state of the system before the measurement.…”

Section: Quantum Operations Quantum Channels and The Choi Isomorphismmentioning

confidence: 99%

“…Advances in quantum communication [1][2][3] and in the integration of quantum hardware [4-8] are pushing towards the realization of networked quantum information systems, such as quantum communication networks [9-13] and distributed quantum computing [14][15][16]. Networks of interacting quantum devices are attracting interest also at the theoretical level, providing a framework for quantum games [17] and protocols [18][19][20], insights on the foundations of quantum mechanics [18, 21-23], a starting point for a general theory of Bayesian inference [24-31] and for the development of models of higher-order quantum computation [32][33][34].…”

Section: Introductionmentioning

confidence: 99%

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Optimal quantum networks and one-shot entropies

Chiribella

Ebler

2016

New J. Phys.

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We develop a semidefinite programming method for the optimization of quantum networks, including both causal networks and networks with indefinite causal structure. Our method applies to a broad class of performance measures, defined operationally in terms of interative tests set up by a verifier. We show that the optimal performance is equal to a max relative entropy, which quantifies the informativeness of the test. Building on this result, we extend the notion of conditional min-entropy from quantum states to quantum causal networks. The optimization method is illustrated in a number of applications, including the inversion, charge conjugation, and controlization of an unknown unitary dynamics. In the non-causal setting, we show a proof-of-principle application to the maximization of the winning probability in a non-causal quantum game. IntroductionAdvances in quantum communication [1][2][3] and in the integration of quantum hardware [4-8] are pushing towards the realization of networked quantum information systems, such as quantum communication networks [9-13] and distributed quantum computing [14][15][16]. Networks of interacting quantum devices are attracting interest also at the theoretical level, providing a framework for quantum games [17] and protocols [18][19][20], insights on the foundations of quantum mechanics [18, 21-23], a starting point for a general theory of Bayesian inference [24-31] and for the development of models of higher-order quantum computation [32][33][34].The network scenario motivates a new set of optimization problems, where the goal is not to optimize individual devices, but rather to optimize how different devices interact with one another. In many situations, the devices operate in a well-defined causal order-this is the case, for example, in the circuit model of quantum computing, where computations are implemented by sequences of gates [35,36]. Recently, researchers have started to investigate more general situations, where the causal order can be in a quantum superposition [20,33,34,[37][38][39] or can be indefinite in other more exotic ways, in principle compatible with quantum mechanics [34,[40][41][42][43][44][45]. In these new situations, optimizing quantum networks is important, for at least three reasons: First, in order to establish an advantage, one has to first find the optimal performances achievable in a definite causal order. Second, finding the maximum advantage requires an optimization over all non-causal networks. This is an essential step for assessing the power of the new, non-causal models of information processing. Third, identifying the ultimate performances achieved in the absence of pre-defined causal structure is expected to shed light on the interplay between quantum mechanics and spacetime.In this paper we develop a semidefinite programming (SDP) approach to the optimization of quantum networks. We start by analyzing scenarios with definite causal order, choosing an operational measure of performance, quantified by how much the network scores in a giv...

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Section: Quantum Operations Quantum Channels and The Choi Isomorphismmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Optimal quantum networks and one-shot entropies

Chiribella

Ebler

2016

New J. Phys.

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“…Advances in quantum communication [1,2,3] and in the integration of quantum hardware [4,5,6,7,8] are pushing towards the realization of networked quantum information systems, such as quantum communication networks [9,10,11,12,13] and distributed quantum computing [14,15,16]. Networks of interacting quantum devices are attracting interest also at the theoretical level, providing a framework for quantum games [17] and protocols [18,19,20], insights on the foundations of quantum mechanics [18,21,22,23], a starting point for a general theory of Bayesian inference [24,25,26,27,28,29,30,31] and for the development of models of higher-order quantum computation [32,33,34].…”

Section: Introductionmentioning

confidence: 99%

Optimal quantum networks and one-shot entropies

Chiribella,

Ebler

2016

Preprint

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“…In recent years, many theoretical and experimental researches have been carried out towards the development of practical QKD systems based on optical fibers [3][4][5][6][7][8][9][10][11][12][13][14] and free-space [15][16][17] . However, people have higher expectations that the quantum secure communication can completely improve the underwater communication.…”

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confidence: 99%

Performance analysis of quantum key distribution based on air-water channel

Zhou

2015

Optoelectron. Lett.

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Considering the air-water interface and ocean water's optical attenuation, the performance of quantum key distribution (QKD) based on air-water channel is studied. The effects of photons' various incident angles to air-water interface on quantum bit error rate (QBER) and the maximum secure transmission distance are analyzed. Taking the optical attenuation of ocean water into account, the performance bounds of QKD in different types of ocean water are discussed. The simulation results show that the maximum secure transmission distance of QKD gradually reduces as the incident angle from air to ocean water increases. In the clearest ocean water with the lowest attenuation, the maximum secure transmission distance of photons far exceeds the the working depth of underwater vehicles. In intermediate and murky ocean waters with higher attenuation, the secure transmission distance shortens, but the underwater vehicle can deploy other accessorial methods for QKD with perfect security. So the implementation of OKD between the satellite and the underwater vehicle is feasible."Quantum secure communication of China Beijing Shanghai line" project has been started, which proves a great leap of quantum key distribution (QKD) [1] from experiment to application [2] . In recent years, many theoretical and experimental researches have been carried out towards the development of practical QKD systems based on optical fibers [3][4][5][6][7][8][9][10][11][12][13][14] and free-space [15][16][17] . However, people have higher expectations that the quantum secure communication can completely improve the underwater communication. Marco Lanzagorta [18] presented a good idea that QKD can be implemented between the satellite and the underwater vehicle to construct a two-way laser communication link with perfect security, and theoretically proved that the implementation of BB84 QKD protocol between two users submerged in ocean water was feasible. Ref. [19] analyzed the influence of the transmission rates of different photon components on quantum bit error rate (QBER) of QKD between different media. However, other than the influence of air-water interface, there is much challenge confronted by the photon signals from air to ocean water, such as the larger optical attenuation of ocean water, various noise and quantum efficiency of photodetector.In this paper, synthetically considering the influence of the air-water interface and the optical attenuation of the ocean water on QKD, the maximum secure transmission distances of BB84 QKD in different types of water are analyzed, and a more comprehensive demonstration for the feasibility of implementing OKD between the satellite and the underwater vehicle is provided.As shown in Fig.1, there is an incident ray with wave vector k from the medium with refractive index n 1 to the medium with refractive index n 2 , and the angle of refraction is γ. Fig.1 Schematic diagram of the photons transmitting between different mediaThen we define t p and t s to be the amplitude transmittances of s component and p co...

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Advanced Quantum Communications Experiments with Entangled Photons

Cited by 4 publications

References 86 publications

Optimal quantum networks and one-shot entropies

Optimal quantum networks and one-shot entropies

Optimal quantum networks and one-shot entropies

Performance analysis of quantum key distribution based on air-water channel

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