Quantum-limited discrimination of laser light and thermal light

Abstract

Understanding the fundamental sensitivity limit of an optical sensor requires a full quantum mechanical description of the sensing task. In this work, we calculate the fundamental (quantum) limit for discriminating between pure laser light and thermal noise in a photon-starved regime. The Helstrom bound for discrimination error probability for single mode measurement is computed along with error probability bounds for direct detection, coherent homodyne detection and the Kennedy receiver. A generalized Kennedy (GK) receiver is shown to closely approach the Helstrom limit. We present an experimental demonstration of this sensing task and demonstrate $15.4$ dB improvement in discrimination sensitivity over direct detection using a GK receiver, and an improvement of $19.4\%$ in error probability over coherent detection.

arXiv comment7 pages, 3 figures

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Cited by in corpus (4)

• Demonstration of quantum-limited discrimination of multi-copy pure versus mixed states
• Lowering Helstrom Bound with non-standard coherent states
• Towards Optimal Quantum Ranging -- Hypothesis Testing for an Unknown Return Signal
• High Fidelity Artificial Quantum Thermal State Generation using Encoded Coherent States