Environment Assisted Metrology with Spin Qubit

TL;DR

This paper explores an environment-assisted quantum sensing method using solid-state spin systems, analyzing sensitivity limits, proposing dynamical decoupling, and strategies to optimize environmental spin polarization for enhanced magnetic field detection.

Contribution

It introduces a detailed analysis of environment-assisted metrology with spin qubits, including methods to extend coherence and polarization, and proposes optimized sample engineering for improved sensitivity.

Findings

Decoherence limits sensitivity but can be mitigated with dynamical decoupling.

Environmental spin polarization significantly enhances measurement sensitivity.

Proposed strategies enable zero polarization operation for quantum sensing.

Abstract

We investigate the sensitivity of a recently proposed method for precision measurement [Phys. Rev. Lett. 106, 140502 (2011)], focusing on an implementation based on solid-state spin systems. The scheme amplifies a quantum sensor response to weak external fields by exploiting its coupling to spin impurities in the environment. We analyze the limits to the sensitivity due to decoherence and propose dynamical decoupling schemes to increase the spin coherence time. The sensitivity is also limited by the environment spin polarization; therefore we discuss strategies to polarize the environment spins and present a method to extend the scheme to the case of zero polarization. The coherence time and polarization determine a figure of merit for the environment's ability to enhance the sensitivity compared to echo-based sensing schemes. This figure of merit can be used to engineer optimized samples for high-sensitivity nanoscale magnetic sensing, such as diamond nanocrystals with controlled impurity density.