Regensburg 2022 – wissenschaftliches Programm

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QI: Fachverband Quanteninformation

QI 2: Quantum Thermodynamics and Open Quantum Systems

QI 2.1: Hauptvortrag

Montag, 5. September 2022, 09:30–10:00, H9

Measuring the thermodynamic cost of timekeeping — •Yelena Guryanova — Institute for Quantum Optics and Quantum Information (IQOQI), Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Vienna, Austria

All clocks, in some form or another, use the evolution towards higher entropy states to quantify the passage of time. Because of the statistical nature of the second law and corresponding entropy flows, fluctuations fundamentally limit the performance of any clock. This suggests a deep relation between the increase in entropy and the quality of clock ticks. Indeed, minimal models for autonomous clocks in the quantum realm revealed that a linear relation can be derived, where for a limited regime entropy linearly increases with the accuracy. Does a linear relation persist as we move toward a more classical system? We answer this in the affirmative by presenting the first experimental investigation of this thermodynamic relation in a nanoscale clock. We stochastically drive a nanometer-thick membrane and read out its displacement with a radio-frequency cavity, allowing us to identify the ticks. We show theoretically that the maximum possible accuracy for this classical clock is proportional to the entropy created per tick, similar to the known limit for a weakly coupled quantum clock but with a different proportionality constant. We measure both the accuracy and the entropy. Once non-thermal noise is accounted for, we find that there is also a linear relation between accuracy and entropy.