Achieving minimum-error discrimination of an arbitrary set of laser-light pulses

Abstract

Laser light is widely used for communication and sensing applications, so the optimal discrimination of coherent states--the quantum states of light emitted by a laser--has immense practical importance. However, quantum mechanics imposes a fundamental limit on how well different coher- ent states can be distinguished, even with perfect detectors, and limits such discrimination to have a finite minimum probability of error. While conventional optical receivers lead to error rates well above this fundamental limit, Dolinar found an explicit receiver design involving optical feedback and photon counting that can achieve the minimum probability of error for discriminating any two given coherent states. The generalization of this construction to larger sets of coherent states has proven to be challenging, evidencing that there may be a limitation inherent to a linear-optics-based adaptive measurement strategy. In this Letter, we show how to achieve optimal discrimination of any set of coherent states using a resource-efficient quantum computer. Our construction leverages a recent result on discriminating multi-copy quantum hypotheses (arXiv:1201.6625) and properties of coherent states. Furthermore, our construction is reusable, composable, and applicable to designing quantum-limited processing of coherent-state signals to optimize any metric of choice. As illustrative examples, we analyze the performance of discriminating a ternary alphabet, and show how the quantum circuit of a receiver designed to discriminate a binary alphabet can be reused in discriminating multimode hypotheses. Finally, we show our result can be used to achieve the quantum limit on the rate of classical information transmission on a lossy optical channel, which is known to exceed the Shannon rate of all conventional optical receivers.

9 pages, 2 figures; v2 Minor corrections

References in corpus (1)

• Binary projective measurement via linear optics and photon counting

Cited by in corpus (17)

• Optimum mixed-state discrimination for noisy entanglement-enhanced sensing
• High Fidelity Teleportation of Continuous Variable Quantum States using Delocalized Single Photons
• Capacity of optical communication in loss and noise with general Gaussian receivers
• Realizable receivers for discriminating arbitrary coherent-state waveforms and multi-copy quantum states near the quantum limit
• Optimal Measurements for Symmetric Quantum States with Applications to Optical Communication
• Real-time calibration of coherent-state receivers: learning by trial and error
• Belief Propagation with Quantum Messages for Quantum-Enhanced Classical Communications
• Searching for interstellar quantum communications
• Superadditive Communication with the Green Machine: A Practical Demonstration of Nonlocality without Entanglement
• Optimal discrimination of optical coherent states cannot always be realized by interfering with coherent light, photon counting, and feedback
• On capacity of optical communications over a lossy bosonic channel with a receiver employing the most general coherent electro-optic feedback control
• Demonstration of quantum advantage by a joint detection receiver for optical communications using quantum belief propagation on a trapped-ion device
• Dephasing in coherent communication with weak signal states
• Quantum computer-enabled receivers for optical communication
• Indirect Measurement for Optimal Quantum Communication Enhanced by Binary Non-standard Coherent States
• Quantum-Processing-Assisted Classical Communications
• Decoding Protocols for Classical Communication on Quantum Channels