Measuring the Thermodynamic Cost of Timekeeping

Pearson, Anna; Guryanova, Yelena; Erker, Paul; Laird, E.; Briggs, G. Andrew D.; Huber, Marcus; Ares, Natalia

doi:10.1103/physrevx.11.021029

Cited by 44 publications

(34 citation statements)

References 37 publications

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“…The measurement itself pushes the system away from thermal equilibrium by decreasing its entropy. As shown in [3], it remains the case that such a clock will require large dissipation for a fixed quality factor, Q. At low temperatures the classical noise becomes small and the fluctuations responsible for driving the clock are disabled.…”

Section: Introductionmentioning

confidence: 99%

Quantum clocks driven by measurement

Gangat¹,

Milburn²

2021

Preprint

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In classical physics, clocks are open dissipative systems driven from thermal equilibrium and necessarily subject to thermal noise. We describe a quantum clock driven by entropy reduction through measurement. The mechanism consists of a superconducting transmon qubit coupled to an open co-planar resonator. The cavity and qubit are driven by coherent fields and the cavity output is monitored with homodyne detection. We show that the measurement itself induces coherent oscillations, with fluctuating period, in the conditional moments. The clock signal can be extracted from the observed measurement currents and analysed to determine the noise performance. The model demonstrates a fundamental principle of clocks at zero temperature: good clocks require high rates of energy dissipation and consequently entropy generation.

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Section: Introductionmentioning

confidence: 99%

Quantum clocks driven by measurement

Gangat¹,

Milburn²

2021

Preprint

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“…The latter entails either divergent entropy production or vanishing speed ẏ . For clocks that require the hand to move forward at a nonvanishing speed, a recent study shows that precision does indeed come at a certain thermodynamic cost [23].…”

mentioning

confidence: 99%

Classical pendulum clocks break the thermodynamic uncertainty relation

Pietzonka

2021

Preprint

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A mechanical clock, such as a pendulum clock, uses an escapement to couple the motion of an oscillator to regulate the motion of another degree of freedom (a "hand") driven by an external force. Clocks built after this principle can yield high precision at low energetic cost. They provide a counterexample to the thermodynamic uncertainty relation, which is thus shown not to hold for systems undergoing driven Brownian diffusion with inertia. Considering a thermodynamically consistent, discrete model for an escapement mechanism, we first show that the oscillations of an underdamped harmonic oscillator in thermal equilibrium are sufficient to break the thermodynamic uncertainty relation. We then show that this is also the case in simulations of a fully continuous underdamped system with a potential landscape that mimics an escaped pendulum.

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“…We believe that the ideas presented here can potentially open up an fertile solid state spintronics platform to encompass emerging ideas in quantum technology such as quantum weak values and its applications, that are currently exclusive to quantum optics and cold atoms. While the setup we describe provides a basic realization of a spintronic Büttiker clock consistent with the interpretations of Steinberg [15], it is left further to look into the thermodynamic aspects of quantum timekeeping via a serious analysis of pointer tick accuracy and efficiency [41][42][43]. Furthermore, mesoscopic quantum Hall setups with quantum point contacts also possess realizable configurations for delving deep into these aspects discussed here.…”

Section: Discussionmentioning

confidence: 71%

Proposal for a solid-state magnetoresistive Larmor quantum clock

Mathew,

Camsari,

Muralidharan

2021

Preprint

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We propose a solid-state implementation of the Larmor clock that exploits tunnel magnetoresistance to distill information on how long itinerant spins take to traverse a barrier embedded in it. Keeping in mind that the tunnelling time innately involves pristine pre-selection and post-selection, our proposal takes into account the detrimental aspects of multiple reflections by incorporating multiple contacts, multiple current measurements and suitably defined magnetoresistance signals. Our analysis provides a direct mapping between the magnetoresistance signals and the tunneling times and aligns well with the interpretation in terms of generalized quantum measurements and quantum weak values. By means of an engineered pre-selection in one of the ferromagnetic contacts, we also elucidate how one can make the measurement "weak" by minimizing the back-action, while keeping the tunneling time unchanged. We then analyze the resulting interpretations of the tunneling time and the measurement back action in the presence of phase breaking effects that are intrinsic to solid state systems. We unravel that while the time-keeping aspect of the Larmor clock is reasonably undeterred due to momentum and phase relaxation processes, it degrades significantly in the presence of spin-dephasing. We believe that the ideas presented here also open up a fructuous solid state platform to encompass emerging ideas in quantum technology such as quantum weak values and its applications, that are currently exclusive to quantum optics and cold atoms.

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Measuring the Thermodynamic Cost of Timekeeping

Cited by 44 publications

References 37 publications

Quantum clocks driven by measurement

Quantum clocks driven by measurement

Classical pendulum clocks break the thermodynamic uncertainty relation

Proposal for a solid-state magnetoresistive Larmor quantum clock

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