Beating the Ramsey limit on sensing with deterministic qubit control
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 frequ...
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| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Nature Portfolio
2025-04-01
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| Series: | Nature Communications |
| Online Access: | https://doi.org/10.1038/s41467-025-58947-4 |
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| Summary: | 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. |
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| ISSN: | 2041-1723 |