Continuous quantum clock with high precision and long recurrence time

TL;DR

This paper proposes models for continuous quantum clocks that achieve high precision and long recurrence times using entangled qubits, analyzing their performance through quantum estimation theory.

Contribution

It introduces quantum clock models based on entangled qubits and compares their performance, highlighting the trade-off between precision and recurrence time.

Findings

Quantum clocks with n entangled qubits outperform those with 2n separate qubits in precision.

Using n entangled qubits improves precision by a factor of 1/√n.

Enhanced precision via entanglement reduces the recurrence time of the clock.

Abstract

Continuous clocks, i.e. the clocks that measure time in a continuous manner, are regarded as an essential component of sensing technology. Precision and recurrence time are two basic features of continuous clocks. In this paper, in the framework of quantum estimation theory various models for continuous quantum clocks are proposed, where all tools of quantum estimation theory are employed to seek the characteristics of clocks with high precision and long recurrence time. Then, in a resource-based approach, the performance of the proposed models is compared. It is shown that quantum clocks based on $n$ two-qubits system not only can have better precision than quantum clocks based on $2n$ one-qubit system but also support long recurrence time. Finally, it is shown that while employing the number of $n$ entangled qubits improves the precision of clocks by a factor of $1/\sqrt n $, it inevitably worsens the recurrence time of the clock.