23.05.+f Fiber-based quantum communication

Quantum memory receiver for superadditive communication using binary coherent states

Date: 
2016-04-12
Author(s): 

Aleksandra Klimek, Michał Jachura, Wojciech Wasilewski, Konrad Banaszek

Reference: 

Journal of Modern Optics, DOI: 10.1080/09500340.2016.1173731 http://arxiv.org/pdf/1512.06561.pdf

We propose a simple architecture based on multimode quantum memories for collective readout of classical information keyed using a pair coherent states, exemplified by the well-known binary phase shift keying format. Such a configuration enables demonstration of the superadditivity effect in classical communication over quantum channels, where the transmission rate becomes enhanced through joint detection applied to multiple channel uses.

Phase noise in collective binary phase shift keying with Hadamard words

Date: 
2016-05-10
Author(s): 

Marcin Jarzyna, Victoria Lipińska, Aleksandra Klimek, Konrad Banaszek, Matteo G. A. Paris

Reference: 

Optics Express 24, 1693-1698 (2016) https://arxiv.org/abs/1509.00009

We analyze the effect of phase fluctuations in an optical communication scheme based on collective detection of sequences of binary coherent state symbols using linear optics and photon counting. When the phase noise is absent, the scheme offers qualitatively improved nonlinear scaling of the spectral efficiency with the mean photon number in the low-power regime compared to individual detection.

Incoherent on-off keying with classical and non-classical light

Date: 
2015-02-09
Author(s): 

Marcin Jarzyna, Piotr Kuszaj, Konrad Banaszek

Reference: 

Optics Express 23, 3170-3175 (2015), http://arxiv.org/abs/1410.4575

We analyze the performance of on-off keying (OOK) and its restricted version pulse position modulation (PPM) over a lossy narrowband optical channel under the constraint of a low average photon number, when direct detection is used at the output. An analytical approximation for the maximum PPM transmission rate is derived, quantifying the effects of photon statistics on the communication efficiency in terms of the g(2) second-order intensity correlation function of the light source. Enhancement attainable through the use of sub-Poissonian light is discussed.

Experimental plug&play quantum coin flipping

Date: 
2013-06-14 - 2013-12-18
Author(s): 

Anna Pappa, Paul Jouguet, Thomas Lawson, André Chailloux, Matthieu Legré, Patrick Trinkler, Iordanis Kerenidis, Eleni Diamanti

Reference: 

arXiv:1306.3368 (under submission)

Performing complex cryptographic tasks will be an essential element in future quantum communication networks. These tasks are based on a handful of fundamental primitives, such as coin flipping, where two distrustful parties wish to agree on a randomly generated bit. Although it is known that quantum versions of these primitives can offer information-theoretic security advantages with respect to classical protocols, a demonstration of such an advantage in a practical communication scenario has remained elusive.

Matrix product states with long-range localizable entanglement

Date: 
2012-12-14
Author(s): 

T. B. Wahl, D. Pérez-García, and J. I. Cirac

Reference: 

URL: http://link.aps.org/doi/10.1103/PhysRevA.86.062314
DOI: 10.1103/PhysRevA.86.062314
PACS: 03.67.Mn, 03.65.Ud, 75.10.Pq, 71.10.Hf

We derive a criterion to determine when a translationally invariant matrix product state (MPS) has long-range localizable entanglement, where that quantity remains finite in the thermodynamic limit. We give examples fulfilling this criterion and eventually use it to obtain all such MPS with bond dimension 2 and 3.

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