Squeezing-enhanced phase-shift-keyed binary communication in noisy channels

Chesi, Giovanni; Olivares, Stefano; Paris, Matteo G. A.

doi:10.1103/physreva.97.032315

Cited by 22 publications

(9 citation statements)

References 31 publications

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“…Our results provide a clear departure from the case of phase-covariant Gaussian channels and prove the unconditional advantage of using non-classical Gaussian light in a physically motivated communication setting. We note that several works observed an enhancement in discrimination and communication in presence of phase noise via the addition of squeezing to coherent states, though with several restrictions on sources and measurements [23,[25][26][27][28][29]. To our knowledge, our work is the first to prove an unconditional advantage.…”

Section: Lossesmentioning

confidence: 66%

“…This can happen when the relative phase drifts during transmission due to a physical mechanism in the medium, e.g., Kerr non-linearities and temperature fluctuations in optical fiber [12][13][14] or turbulence effects in free space [15]; but it can also be an effective result of other mechanisms, e.g., the use of a photodetector to measure the signals or the presence of a malicious eavesdropper [16,17]. Several works analyzed the effect of phase noise on common communication methods based on coherent states encodings [18][19][20][21][22][23].…”

Section: Introductionmentioning

confidence: 99%

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Squeezing-enhanced communication without a phase reference

Fanizza

Rosati

Skotiniotis

et al. 2021

Quantum

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We study the problem of transmitting classical information using quantum Gaussian states on a family of phase-noise channels with a finite decoherence time, such that the phase-reference is lost after m consecutive uses of the transmission line. This problem is relevant for long-distance communication in free space and optical fiber, where phase noise is typically considered as a limiting factor. The Holevo capacity of these channels is always attained with photon-number encodings, challenging with current technology. Hence for coherent-state encodings the optimal rate depends only on the total-energy distribution and we provide upper and lower bounds for all m, the latter attainable at low energies with on/off modulation and photodetection. We generalize this lower bound to squeezed-coherent encodings, exhibiting for the first time to our knowledge an unconditional advantage with respect to any coherent encoding for m=1 and a considerable advantage with respect to its direct coherent counterpart for m>1. This advantage is robust with respect to moderate attenuation, and persists in a regime where Fock encodings with up to two-photon states are also suboptimal. Finally, we show that the use of part of the energy to establish a reference frame is sub-optimal even at large energies. Our results represent a key departure from the case of phase-covariant Gaussian channels and constitute a proof-of-principle of the advantages of using non-classical, squeezed light in a motivated communication setting.

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Section: Lossesmentioning

confidence: 66%

Section: Introductionmentioning

confidence: 99%

Squeezing-enhanced communication without a phase reference

Fanizza

Rosati

Skotiniotis

et al. 2021

Quantum

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“…The optimal situation corresponds to squeezed coherent states with PSK encoding. This alphabet was studied in [ 18 , 23 ] and is further explored here. What is more, we have shown that this case is valid for more general values of the angular parameters

and

, provided

.…”

Section: Discussionmentioning

confidence: 99%

“…Note that this optimality condition does not hold for a general squeezed state. This is equivalent to the squeezed states studied in [ 18 ], even though the authors had fixed

from the start. This means that their expression is actually valid for more general values of

and

as we have shown here.…”

Section: Helstrom Bound For Squeezed Coherent Statesmentioning

confidence: 97%

“…Extending our study to squeezed states is motivated by their relevance on the experimental level, and the importance to find the best parameters in order to minimize the quantum error. In [ 18 ], the state discrimination in binary communication with a phase-shift keyed (PSK) alphabet of squeezed coherent states was studied. Here we want to extend the study of state discrimination to alphabets made of two arbitrary squeezed coherent states where the only imposed constraint is fixing the energy (average number of photons) for each letter of the alphabet.…”

Section: Introductionmentioning

confidence: 99%

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Helstrom Bound for Squeezed Coherent States in Binary Communication

Curado

Faci

Gazeau

et al. 2022

Entropy

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In quantum information processing, using a receiver device to differentiate between two non-orthogonal states leads to a quantum error probability. The minimum possible error is known as the Helstrom bound. In this work, we study the conditions for state discrimination using an alphabet of squeezed coherent states and compare them with conditions using the Glauber-Sudarshan, i.e., standard, coherent states.

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Process estimation in qubit systems: a quantum decision theory approach

Maffeis

Koudia

Gharbi

et al. 2019

Quantum Inf Process

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We address quantum decision theory as a convenient framework to analyze process discrimination and estimation in qubit systems. In particular we discuss the following problems: i) how to discriminate whether or not a given unitary perturbation has been applied to a qubit system; ii) how to determine the amplitude of the minimum detectable perturbation. In order to solve the first problem, we exploit the so-called Bayes strategy, and look for the optimal measurement to discriminate, with minimum error probability, whether or not the unitary transformation has been applied to a given signal. Concerning the second problem, the strategy of Neyman and Pearson is used to determine the ultimate bound posed by quantum mechanics to the minimum detectable amplitude of the qubit transformation. We consider both pure and mixed initial preparations of the qubit, and solve the corresponding binary decision problems. We also analyze the use of entangled qubits in the estimation protocol and found that entanglement, in general, improves stability rather than precision. Finally, we take into account the possible occurrence of different kinds of background noise and evaluate the corresponding effects on the discrimination strategies.

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Squeezing-enhanced phase-shift-keyed binary communication in noisy channels

Cited by 22 publications

References 31 publications

Squeezing-enhanced communication without a phase reference

Squeezing-enhanced communication without a phase reference

Helstrom Bound for Squeezed Coherent States in Binary Communication

Process estimation in qubit systems: a quantum decision theory approach

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