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arXiv · 2306.01622

Quantum spectral analysis by continuous measurement of Landau-Zener transitions

Christopher C. Bounds·Josh P. Duff·Alex Tritt·Hamish A. M. Taylor·George X. Coe·Sam J. White·L. D. Turner
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Abstract

We demonstrate the simultaneous estimation of signal frequency and amplitude by a single quantum sensor in a single experimental shot. Sweeping the qubit splitting linearly across a span of frequencies induces a non-adiabatic Landau-Zener transition as the qubit crosses resonance. The signal frequency determines the time of the transition, and the amplitude its extent. Continuous weak measurement of this unitary evolution informs a parameter estimator retrieving precision measurements of frequency and amplitude. Implemented on radiofrequency-dressed ultracold atoms read out by a Faraday spin-light interface, we sense a magnetic signal with $20~\text{pT}$ precision in amplitude, and near-transform-limited precision in frequency, in a single $300~\text{ms}$ sweep from $7$ to $13~\text{kHz}$. The protocol realizes a swept-sine quantum spectrum analyzer, potentially sensing hundreds or thousands of channels with a single quantum sensor.

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Christopher C. Bounds, Josh P. Duff, Alex Tritt, Hamish A. M. Taylor, George X. Coe, Sam J. White, L. D. Turner. 2023-06-02. Quantum spectral analysis by continuous measurement of Landau-Zener transitions. https://doi.org/10.1103/physrevlett.132.093401

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