# Quantum Stopwatch: How To Store Time in a Quantum Memory

## TL;DR

This paper introduces a quantum method to store and transfer time information with minimal error accumulation, enabling more accurate measurement of event durations and efficient clock stabilization in quantum networks.

## Contribution

The authors propose a novel quantum memory technique that coherently transfers time information, reducing error growth compared to traditional methods.

## Key findings

- Method theoretically avoids error accumulation in quantum time measurements.
- Potential to improve accuracy of measuring total durations of event sequences.
- Reduces quantum communication needed for clock stabilization in networks.

## Abstract

Quantum mechanics imposes a fundamental tradeoff between the accuracy of time measurements and the size of the systems used as clocks. When the measurements of different time intervals are combined, the errors due to the finite clock size accumulate, resulting in an overall inaccuracy that grows with the complexity of the setup. Here we introduce a method that in principle eludes the accumulation of errors by coherently transferring information from a quantum clock to a quantum memory of the smallest possible size. Our method could be used to measure the total duration of a sequence of events with enhanced accuracy, and to reduce the amount of quantum communication needed to stabilize clocks in a quantum network.