Dynamical decoupling leads to improved scaling in noisy quantum metrology

TL;DR

This paper shows that using ultra-fast local control operations in quantum metrology can effectively eliminate most noise types, enabling Heisenberg scaling and surpassing standard limits even with certain parallel noise.

Contribution

It introduces a method of dynamical decoupling in quantum metrology that significantly improves noise mitigation and scaling performance.

Findings

Almost all noise types can be eliminated with local control.

Heisenberg scaling is achievable despite noise.

Improved scaling over the standard quantum limit for certain parallel noise.

Abstract

We consider the usage of dynamical decoupling in quantum metrology, where the joint evolution of system plus environment is described by a Hamiltonian. We demonstrate that by ultra-fast unitary control operations acting locally only on system qubits, essentially all kinds of noise can be eliminated. This is done in such a way that the desired evolution is reduced by at most a constant factor, leading to Heisenberg scaling. The only exception is noise that is generated by the Hamiltonian to be estimated itself. However, even for such parallel noise, one can achieve an improved scaling as compared to the standard quantum limit for any local noise by means of symmetrization.