Quantum speed limit in quantum sensing

TL;DR

This paper explores the fundamental quantum speed limit (QSL) in quantum sensing, demonstrating how it constrains time resolution and proposing control sequences that reach this limit, with practical implications for NV center sensors.

Contribution

It establishes the connection between quantum speed limit and time-resolved sensing, proposing a composite control sequence that achieves the QSL in practical quantum sensors.

Findings

The best time resolution is limited by the quantum speed limit.

A composite control sequence of two phase-shifted pulses reaches the QSL.

Practical implementation is demonstrated with NV center spin-1 qutrits.

Abstract

Quantum sensors capitalize on advanced control sequences for maximizing sensitivity and precision. However, protocols are not usually optimized for temporal resolution. Here, we establish the limits for time-resolved sensing of dynamical signals using qubit probes. We show that the best possible time resolution is closely related to the quantum speed limit (QSL), which describes the minimum time needed to transform between basis states. We further show that a composite control sequence consisting of two phase-shifted pulses reaches the QSL. Practical implementation is discussed based on the example of the spin-1 qutrit of a nitrogen-vacancy (NV) center in diamond.