Protecting and Enhancing Spin Squeezing via Continuous Dynamical Decoupling

TL;DR

This paper demonstrates that continuous dynamical decoupling fields can simultaneously suppress decoherence and enhance spin squeezing, achieving near-Heisenberg limit performance in noisy quantum systems.

Contribution

It introduces a simple continuous DD scheme that both protects against decoherence and improves spin squeezing, approaching the Heisenberg limit.

Findings

Continuous DD fields suppress collective decoherence effectively.

Achieves a 1/N scaling of spin squeezing performance.

Predictions are experimentally feasible with current technology.

Abstract

Realizing useful quantum operations with high fidelity is a two-task quantum control problem wherein decoherence is to be suppressed and desired unitary evolution is to be executed. The dynamical decoupling (DD) approach to decoherence suppression has been fruitful but synthesizing DD fields with certain quantum control fields may be experimentally demanding. In the context of spin squeezing, here we explore an unforeseen possibility that continuous DD fields may serve dual purposes at once. In particular, it is shown that a rather simple configuration of DD fields can suppress collective decoherence and yield a 1/N scaling of the squeezing performance (N is the number of spins), thus making spin squeezing more robust to noise and much closer to the so-called Heisenberg limit. The theoretical predictions should be within the reach of current spin squeezing experiments.