Physical Chemistry Seminar: First-Passage Times in Monitored Quantum Systems on IBM NISQ Platforms

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Abstract:

We introduce a time-energy uncertainty relation within the context of monitored quantum dynamics [1] . Previous studies have established that the mean recurrence time, which represents the time taken to return to the initial state, is quantized as an integer multiple of the sampling time, displaying point-wise discontinuous transitions at resonances. Our ndings demonstrate that the natural utilization of the restart mechanism in laboratory experiments [2], driven by nite data collection time spans, leads to a broadening eect on the transitions of the mean recurrence time. Our proposed uncertainty relation captures the underlying essence of these phenomena, by connecting the broadening of the mean hitting time near resonances, to the intrinsic energies of the quantum system and to the uctuations of recurrence time. Our uncertainty relation has also been validated through remote experiments conducted on an International Business Machines Corporation (IBM) quantum computer. We then discuss fractional quantization of the recurrence time for interacting spin systems using sub-space measurements [3].

References:

[1] R. Yin, Q. Wang, S. Tornow, and E. Barkai, Restart uncertainty relation for monitored quantum dynamics Proceedings of the National Academy of Sciences 122 (1) e2402912121, (2025).

[2] R. Yin, E. Barkai Restart expedites quantum walk hitting times Phys. Rev. Lett. 130, 050802 (2023).

[3] Q. Liu, S. Tornow, D. A. Kessler, and E. Barkai Fractionally Quantized Recurrence Detection Times in Monitored Quantum Many-Body Systems Proceedings of the National Academy of Sciences 123 (22) e2529694123 (2026).

Seminar Organizer: Prof. Yuval Ebenstein