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arXiv · 2406.01859

Variational quantum state preparation for quantum-enhanced metrology in noisy systems

Juan C. Zuñiga Castro·Jeffrey Larson·Sri Hari Krishna Narayanan·Victor E. Colussi·Michael A. Perlin·Robert J. Lewis-Swan
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Abstract

We investigate optimized quantum state preparation for quantum metrology applications in noisy environments. Using the QFI-Opt package, we simulate a low-depth variational quantum circuit (VQC) composed of a sequence of global rotations and entangling operations applied to a chain of qubits that are subject to dephasing noise. The parameters controlling the VQC are numerically optimized to maximize the quantum Fisher information, which characterizes the ultimate metrological sensitivity of a quantum state with respect to a global rotation. We find that regardless of the details of the entangling operation implemented in the VQC, the optimal quantum states can be broadly classified into a trio of qualitative regimes--cat-like, squeezed-like, and product states--associated with different dephasing rates. Our findings are relevant for designing optimal state-preparation strategies for next-generation quantum sensors exploiting entanglement, such as time and frequency standards and magnetometers, aimed at achieving state-of-the-art performance in the presence of noise and decoherence.

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Juan C. Zuñiga Castro, Jeffrey Larson, Sri Hari Krishna Narayanan, Victor E. Colussi, Michael A. Perlin, Robert J. Lewis-Swan. 2024-06-04. Variational quantum state preparation for quantum-enhanced metrology in noisy systems. https://doi.org/10.1103/physreva.110.052615

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