Continuous Quantum Hypothesis Testing

Abstract

I propose a general quantum hypothesis testing theory that enables one to test hypotheses about any aspect of a physical system, including its dynamics, based on a series of observations. For example, the hypotheses can be about the presence of a weak classical signal continuously coupled to a quantum sensor, or about competing quantum or classical models of the dynamics of a system. This generalization makes the theory useful for quantum detection and experimental tests of quantum mechanics in general. In the case of continuous measurements, the theory is significantly simplified to produce compact formulae for the likelihood ratio, the central quantity in statistical hypothesis testing. The likelihood ratio can then be computed efficiently in many cases of interest. Two potential applications of the theory, namely quantum detection of a classical stochastic waveform and test of harmonic-oscillator energy quantization, are discussed.Comment: v1: first draft; v2: updated and submitted; v3: accepted by PRL, 5 pages, 1 figure, and Supplementary Materia