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arXiv · 1603.02137

Spectrum analysis with quantum dynamical systems

Shilin Ng·Shan Zheng Ang·Trevor A. Wheatley·Hidehiro Yonezawa·Akira Furusawa·Elanor H. Huntington·Mankei Tsang
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Abstract

Measuring the power spectral density of a stochastic process, such as a stochastic force or magnetic field, is a fundamental task in many sensing applications. Quantum noise is becoming a major limiting factor to such a task in future technology, especially in optomechanics for temperature, stochastic gravitational wave, and decoherence measurements. Motivated by this concern, here we prove a measurement-independent quantum limit to the accuracy of estimating the spectrum parameters of a classical stochastic process coupled to a quantum dynamical system. We demonstrate our results by analyzing the data from a continuous optical phase estimation experiment and showing that the experimental performance with homodyne detection is close to the quantum limit. We further propose a spectral photon counting method that can attain quantum-optimal performance for weak modulation and a coherent-state input, with an error scaling superior to that of homodyne detection at low signal-to-noise ratios.

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Shilin Ng, Shan Zheng Ang, Trevor A. Wheatley, Hidehiro Yonezawa, Akira Furusawa, Elanor H. Huntington, Mankei Tsang. 2016-03-07. Spectrum analysis with quantum dynamical systems. https://doi.org/10.1103/physreva.93.042121

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