Recovering noise-free quantum observables

TL;DR

This paper presents a technique to recover noise-free quantum observables by combining results from multiple experiments with known variations in error properties, improving quantum measurement accuracy without significant qubit overhead.

Contribution

The method offers a new approach to mitigate noise in quantum systems that requires only evaluation overhead, not additional qubits, and is applicable to quantum computing and sensing.

Findings

Effective increase in $T_1$ and $T_2$ times demonstrated in simulations and experiments.

Enhanced correction of entangled states and extended Ramsey fringes.

Method reduces noise impact without qubit overhead, enabling better quantum measurements.

Abstract

We introduce a technique for recovering noise-free observables in noisy quantum systems by combining the results of many slightly different experiments. Our approach is applicable to a variety of quantum systems but we illustrate it with applications to quantum computing and quantum sensing. The approach corresponds to repeating the same quantum evolution many times with known variations on the underlying systems' error properties, e.g. the spontaneous emission and dephasing times, $T_1$ and $T_2$. As opposed to standard quantum error correction methods, which have an overhead in the number of qubits (many physical qubits must be added for each logical qubit) our method has only an overhead in number of evaluations, allowing the overhead to, in principle, be hidden via parallelization. We show that the effective spontaneous emission, $T_1$, and dephasing, $T_2$, times can be increased using this method in both simulation and experiments on an actual quantum computer. We also show how to correct more complicated entangled states and how Ramsey fringes relevant to quantum sensing can be significantly extended in time.