Motion and gravity effects in the precision of quantum clocks

TL;DR

This paper investigates how motion and gravity influence the precision of quantum clocks, revealing that relativistic effects can degrade or even enhance measurement accuracy depending on the quantum states used.

Contribution

It introduces a model of quantum clocks affected by relativistic motion and analyzes how different quantum states respond to these effects on measurement precision.

Findings

Squeezed vacuum states are highly sensitive to motion-induced degradation.

Coherent states are more resilient to relativistic effects.

Under certain conditions, motion can improve clock precision with low photon numbers.

Abstract

We show that motion and gravity affect the precision of quantum clocks. We consider a localised quantum field as a fundamental model of a quantum clock moving in spacetime and show that its state is modified due to changes in acceleration. By computing the quantum Fisher information we determine how relativistic motion modifies the ultimate bound in the precision of the measurement of time. While in the absence of motion the squeezed vacuum is the ideal state for time estimation, we find that it is highly sensitive to the motion-induced degradation of the quantum Fisher information. We show that coherent states are generally more resilient to this degradation and that in the case of very low initial number of photons, the optimal precision can be even increased by motion. These results can be tested with current technology by using superconducting resonators with tunable boundary conditions.