Quantum clocks driven by measurement

TL;DR

This paper introduces a quantum clock driven by measurement-induced entropy reduction, demonstrating that measurement can induce coherent oscillations and that high energy dissipation is essential for accurate timekeeping at zero temperature.

Contribution

It presents a novel quantum clock model driven by measurement, highlighting the role of entropy reduction and energy dissipation in clock performance.

Findings

Measurement induces coherent oscillations in the quantum clock.

Clock accuracy improves with higher energy dissipation.

The model demonstrates fundamental principles of zero-temperature clocks.

Abstract

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.