Detecting quantum noise of a solid-state spin ensemble with dispersive measurement

• URL: http://arxiv.org/abs/2602.03734v1
• Date: Tue, 03 Feb 2026 16:55:03 GMT
• Title: Detecting quantum noise of a solid-state spin ensemble with dispersive measurement
• Authors: Mikhail Mamaev, Jayameenakshi Venkatraman, Martin Koppenhöfer, Ania C. Bleszynski Jayich, Aashish A. Clerk,
• Abstract summary: We study dispersive readout of an inhomogeneously broadened spin ensemble via coupling to a driven resonator measured via homodyne detection.<n>By studying fluctuations of the measurement record in detail, we also propose an experimental protocol for directly detecting spin squeezing.
• Score: 0.0
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: We theoretically explore protocols for measuring the spin polarization of an ensemble of solid-state spins, with precision at or below the standard quantum limit. Such measurements in the solid-state are challenging, as standard approaches based on optical fluorescence are often limited by poor readout fidelity. Indirect microwave resonator-mediated measurements provide an attractive alternative, though a full analysis of relevant sources of measurement noise is lacking. In this work we study dispersive readout of an inhomogeneously broadened spin ensemble via coupling to a driven resonator measured via homodyne detection. We derive generic analytic conditions for when the homodyne measurement can be limited by the fundamental spin-projection noise, as opposed to microwave-drive shot noise or resonator phase noise. By studying fluctuations of the measurement record in detail, we also propose an experimental protocol for directly detecting spin squeezing, i.e. a reduction of the spin ensemble's intrinsic projection noise from entanglement. Our protocol provides a method for benchmarking entangled states for quantum-enhanced metrology.

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