Entanglement-enhanced ac magnetometry in the presence of Markovian noise

Journal Article · Mon Apr 07 00:00:00 EDT 2025 · Physical Review A

DOI:https://doi.org/10.1103/physreva.111.042605· OSTI ID:2568058

Sichanugrist, Thanaporn ^[1]; Fukuda, Hajime ^[1]; Moroi, Takeo ^[2]; Nakayama, Kazunori ^[3]; Chigusa, So ^[4]; Mizuochi, Norikazu ^[5]; Hazumi, Masashi ^[6]; Matsuzaki, Yuichiro ^[7]

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1. Univ. of Tokyo (Japan)
2. Univ. of Tokyo (Japan); High Energy Accelerator Research Organization (KEK), Tsukuba (Japan)
3. Tohoku Univ., Sendai (Japan); High Energy Accelerator Research Organization (KEK), Tsukuba (Japan)
4. Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); University of California, Berkeley, CA (United States); Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
5. High Energy Accelerator Research Organization (KEK), Tsukuba (Japan); Kyoto Univ. (Japan)
6. High Energy Accelerator Research Organization (KEK), Tsukuba (Japan); Japan Aerospace Exploration Agency (ISAS/JAXA), Sagamihara, Kanagawa (Japan); Univ. of Tokyo (Japan). Kavli Institute for the Physics and Mathematics of the Universe (WPI); The Graduate University for Advanced Studies (SOKENDAI), Kanagawa (Japan)
7. Chuo University, Tokyo (Japan)

Entanglement is a resource to improve the sensitivity of quantum sensors. In an ideal case, using an entangled state as a probe to detect target fields, we can beat the standard quantum limit by which all classical sensors are bounded. However, since entanglement is fragile against decoherence, it is unclear whether entanglement-enhanced metrology is useful in a noisy environment. Its benefit is indeed limited when estimating the amplitude of dc magnetic fields under the effect of parallel Markovian decoherence, where the noise operator is parallel to the target field. In this paper, on the contrary, we show an advantage to using an entanglement over the classical strategy under the effect of parallel Markovian decoherence when we try to detect ac magnetic fields. We consider a scenario to induce a Rabi oscillation of the qubits with the target ac magnetic fields. Although we can, in principle, estimate the amplitude of the ac magnetic fields from the Rabi oscillation, the signal becomes weak if the qubit frequency is significantly detuned from the frequency of the ac magnetic field. We show that, by using the Greenberger-Horne-Zeilinger (GHZ) states, we can significantly enhance the signal of the detuned Rabi oscillation even under the effect of parallel Markovian decoherence. Further, our method is based on the fact that the interaction time between the GHZ states and ac magnetic fields scales as 1/L to mitigate the decoherence effect, where L is the number of qubits, which contributes to improving the bandwidth of the detectable frequencies of the ac magnetic fields. Our results pave the way for new applications of entanglement-enhanced ac magnetometry.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: Japan Society for the Promotion of Science (JSPS); Simons Foundation; USDOE Office of Science (SC), High Energy Physics (HEP)
• Grant/Contract Number: AC02-05CH11231; SC0012704
• OSTI ID: 2568058
• Alternate ID(s): OSTI ID: 2549458
• Journal Information: Physical Review A, Journal Name: Physical Review A Journal Issue: 4 Vol. 111; ISSN 2469-9934; ISSN 2469-9926
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
Markovian processes
Noise
Quantum metrology
Quantum sensing