A spin-refrigerated cavity quantum electrodynamic sensor.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 39609376.
- Also identified by DOI 10.1038/s41467-024-54333-8 and PMC identifier 11605127.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Quantum sensors based on solid-state defects, in particular nitrogen-vacancy (NV) centers in diamond, enable precise measurement of magnetic fields, temperature, rotation, and electric fields. Cavity quantum electrodynamic (cQED) readout, in which an NV ensemble is hybridized with a microwave mode, can overcome limitations in optical spin detection and has resulted in leading magnetic sensitivities at the pT-level. This approach, however, remains far from the intrinsic spin-projection noise limit due to thermal Johnson-Nyquist noise and spin saturation effects. Here we tackle these challenges by combining recently demonstrated spin refrigeration techniques with comprehensive nonlinear modeling of the cQED sensor operation. We demonstrate that the optically-polarized NV ensemble simultaneously provides magnetic sensitivity and acts as a heat sink for the deleterious thermal microwave noise background, even when actively probed by a microwave field. Optimizing the NV-cQED system, we demonstrate a broadband sensitivity of 576 ± 6 fT/ <math xmlns="http://www.w3.org/1998/Math/MathML"> <msqrt><mrow><mi>Hz</mi></mrow> </msqrt> </math> around 15 kHz in ambient conditions. We then discuss the implications of this approach for the design of future magnetometers, including near-projection-limited devices approaching 3 fT/ <math xmlns="http://www.w3.org/1998/Math/MathML"> <msqrt><mrow><mi>Hz</mi></mrow> </msqrt> </math> sensitivity enabled by spin refrigeration.