Real-time calibration of coherent-state receivers: Learning by trial and error

The optimal discrimination of coherent states of light with current technology is a key problem in classical and quantum communication, whose solution would enable the realization of efficient receivers for long-distance communications in free-space and optical fiber channels. In this paper, we show...

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Main Authors: M. Bilkis, M. Rosati, R. Morral Yepes, J. Calsamiglia
Format: Article
Language:English
Published: American Physical Society 2020-08-01
Series:Physical Review Research
Online Access:http://doi.org/10.1103/PhysRevResearch.2.033295
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author M. Bilkis
M. Rosati
R. Morral Yepes
J. Calsamiglia
author_facet M. Bilkis
M. Rosati
R. Morral Yepes
J. Calsamiglia
author_sort M. Bilkis
collection DOAJ
description The optimal discrimination of coherent states of light with current technology is a key problem in classical and quantum communication, whose solution would enable the realization of efficient receivers for long-distance communications in free-space and optical fiber channels. In this paper, we show that reinforcement learning (RL) protocols allow an agent to learn near-optimal coherent-state receivers made of passive linear optics, photodetectors, and classical adaptive control. Each agent is trained and tested in real time over several runs of independent discrimination experiments and has no knowledge about the energy of the states nor the receiver setup nor the quantum-mechanical laws governing the experiments. Based exclusively on the observed photodetector outcomes, the agent adaptively chooses among a set of ∼3×10^{3} possible receiver setups and obtains a reward at the end of each experiment if its guess is correct. At variance with previous applications of RL in quantum physics, the information gathered at each run is intrinsically stochastic and thus insufficient to evaluate exactly the performance of the chosen receiver. Nevertheless, we present families of agents that: (i) discover a receiver beating the best Gaussian receiver after ∼3×10^{2} experiments; (ii) surpass the cumulative reward of the best Gaussian receiver after ∼10^{3} experiments; (iii) simultaneously discover a near-optimal receiver and attain its cumulative reward after ∼10^{5} experiments. Our results show that RL techniques are suitable for online control of quantum receivers and can be employed for long-distance communications over potentially unknown channels.
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spelling doaj.art-3bdaa666c9354cd9b265b0c564971be32024-04-12T16:59:23ZengAmerican Physical SocietyPhysical Review Research2643-15642020-08-012303329510.1103/PhysRevResearch.2.033295Real-time calibration of coherent-state receivers: Learning by trial and errorM. BilkisM. RosatiR. Morral YepesJ. CalsamigliaThe optimal discrimination of coherent states of light with current technology is a key problem in classical and quantum communication, whose solution would enable the realization of efficient receivers for long-distance communications in free-space and optical fiber channels. In this paper, we show that reinforcement learning (RL) protocols allow an agent to learn near-optimal coherent-state receivers made of passive linear optics, photodetectors, and classical adaptive control. Each agent is trained and tested in real time over several runs of independent discrimination experiments and has no knowledge about the energy of the states nor the receiver setup nor the quantum-mechanical laws governing the experiments. Based exclusively on the observed photodetector outcomes, the agent adaptively chooses among a set of ∼3×10^{3} possible receiver setups and obtains a reward at the end of each experiment if its guess is correct. At variance with previous applications of RL in quantum physics, the information gathered at each run is intrinsically stochastic and thus insufficient to evaluate exactly the performance of the chosen receiver. Nevertheless, we present families of agents that: (i) discover a receiver beating the best Gaussian receiver after ∼3×10^{2} experiments; (ii) surpass the cumulative reward of the best Gaussian receiver after ∼10^{3} experiments; (iii) simultaneously discover a near-optimal receiver and attain its cumulative reward after ∼10^{5} experiments. Our results show that RL techniques are suitable for online control of quantum receivers and can be employed for long-distance communications over potentially unknown channels.http://doi.org/10.1103/PhysRevResearch.2.033295
spellingShingle M. Bilkis
M. Rosati
R. Morral Yepes
J. Calsamiglia
Real-time calibration of coherent-state receivers: Learning by trial and error
Physical Review Research
title Real-time calibration of coherent-state receivers: Learning by trial and error
title_full Real-time calibration of coherent-state receivers: Learning by trial and error
title_fullStr Real-time calibration of coherent-state receivers: Learning by trial and error
title_full_unstemmed Real-time calibration of coherent-state receivers: Learning by trial and error
title_short Real-time calibration of coherent-state receivers: Learning by trial and error
title_sort real time calibration of coherent state receivers learning by trial and error
url http://doi.org/10.1103/PhysRevResearch.2.033295
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