Beating the Ramsey limit on sensing with deterministic qubit control.
basic_science · Level V
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- Record sourced from PubMed, PMID 40301346.
- Also identified by DOI 10.1038/s41467-025-58947-4 and PMC identifier 12041591.
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Abstract
Qubit frequency shifts, which often contain information about a target environment variable, are detected with Ramsey interference measurements. Unfortunately, the sensitivity of this protocol is limited by decoherence. We introduce a new protocol to enhance the sensitivity of a qubit frequency measurement in the presence of decoherence by applying a continuous drive to stabilize one component of the Bloch vector. We demonstrate our protocol on a superconducting qubit, enhancing sensitivity per measurement shot by 1.65 × and sensitivity per qubit evolution time by 1.09 × compared to Ramsey. We also explore the protocol theoretically, finding unconditional enhancements compared to Ramsey interferometry and maximum enhancements of 1.96 × and 1.18 × , respectively. Additionally, our protocol is robust to parameter miscalibrations. It requires no feedback and no extra control or measurement resources, and can be immediately applied in a wide variety of quantum computing and quantum sensor technologies.