Capacity of optical communication in loss and noise with general Gaussian receivers

Abstract

Laser-light (coherent-state) modulation is sufficient to achieve the ultimate (Holevo) capacity of classical communication over a lossy and noisy optical channel, but requires a receiver that jointly detects long modulated codewords with highly nonlinear quantum operations, which are near-impossible to realize using current technology. We analyze the capacity of the lossy-noisy optical channel when the transmitter uses coherent state modulation but the receiver is restricted to a general quantum-limited Gaussian receiver, i.e., one that may involve arbitrary combinations of Gaussian operations (passive linear optics: beamsplitters and phase-shifters, second order nonlinear optics (or active linear optics): squeezers, along with homodyne or heterodyne detection measurements) and any amount of classical feedforward within the receiver. Under these assumptions, we show that the Gaussian receiver that attains the maximum mutual information is either homodyne detection, heterodyne detection, or time sharing between the two, depending upon the received power level. In other words, our result shows that to exceed the theoretical limit of conventional coherent optical communications, one has to incorporate non-Gaussian, i.e., third or higher-order nonlinear operations in the receiver. Finally we compare our Gaussian receiver limit with experimentally feasible non-Gaussian receivers and show that in the regime of low received photon flux, it is possible to overcome the Gaussian receiver limit by relatively simple non-Gaussian receivers based on photon counting.

11 pages, 7 figures. v2: Numerical results added. v3: New section discussing the non-Gaussian receivers is added (Sec. IV)

References in corpus (8)

• A No-Go Theorem for Gaussian Quantum Error Correction
• Ultimate communication capacity of quantum optical channels by solving the Gaussian minimum-entropy conjecture
• Discrimination of the binary coherent signal: Gaussian-operation limit and simple non-Gaussian near-optimal receivers
• The optimal cloning of quantum coherent states is non-Gaussian
• Discrimination of binary coherent states using a homodyne detector and a photon number resolving detector
• Quantum receivers with squeezing and photon-number-resolving detectors
• Sequential projective measurements for channel decoding
• The classical capacity of quantum thermal noise channels to within 1.45 bits

Cited by in corpus (32)

• Quantum Limits in Optical Communications
• Multi-state discrimination below the quantum noise limit at the single-photon level
• Could Gaussian regenerative stations act as quantum repeaters?
• Optimal Measurements for Symmetric Quantum States with Applications to Optical Communication
• Multi-Phase Hadamard receivers for classical communication on lossy bosonic channels
• Approximate reversal of quantum Gaussian dynamics
• Real-time calibration of coherent-state receivers: learning by trial and error
• Incoherent on-off keying with classical and non-classical light
• The capacity of coherent-state adaptive decoders with interferometry and single-mode detectors
• Bayesian homodyne and heterodyne tomography
• Interstellar communication network. I. Overview and assumptions
• Gaussian benchmark for optical communication aiming towards ultimate capacity
• Entanglement Enhanced Estimation of a Parameter Embedded in Multiple Phases
• Approaching the ultimate capacity limit in deep-space optical communication
• On the classical capacity of quantum Gaussian measurement
• Superadditive Communication with the Green Machine: A Practical Demonstration of Nonlocality without Entanglement
• Dense Coding with Locality Restriction for Decoder: Quantum Encoders vs. Super-Quantum Encoders
• Classical capacity per unit cost for quantum channels
• Quantum Channel Capacities Per Unit Cost
• Demonstration of quantum advantage by a joint detection receiver for optical communications using quantum belief propagation on a trapped-ion device
• Classical capacity of Gaussian communication under a single noisy channel
• Proof of the Gaussian maximizers conjecture for the communication capacity of noisy heterodyne measurements
• Transceiver designs to attain the entanglement assisted communications capacity
• Effect of dark counts on single photon heralding with quasi-number-resolving detection schemes
• Limit of Gaussian operations and measurements for Gaussian state discrimination, and its application to state comparison
• Employing weak-field homodyne detection for quantum communications
• Attaining classical capacity per unit cost of noisy bosonic Gaussian channels
• Non-Gaussian entanglement criteria for atomic homodyne detection
• Loss tolerant cross-Kerr enhancement via modulated squeezing
• Quantum-Processing-Assisted Classical Communications
• Optimized Receiver Design for Entanglement-Assisted Communication using BPSK
• Mutual information of optical communication in phase conjugating Gaussian channels