Characterization of Leakage Errors via Randomized Benchmarking

TL;DR

This paper introduces scalable randomized benchmarking protocols to efficiently estimate and minimize leakage errors in quantum systems, which are critical for fault-tolerant quantum computing.

Contribution

The authors develop robust, scalable protocols for quantifying leakage errors, addressing a key challenge in quantum control and error correction.

Findings

Protocols accurately estimate leakage rates in simulations

Leakage errors can be effectively minimized using control variations

Numerical simulations validate protocol reliability

Abstract

Leakage errors arise when the quantum state leaks out of some subspace of interest, for example, the two-level subspace of a multi-level system defining a computational `qubit' or the logical code space defined by some quantum error-correcting code or decoherence-free subspace. Leakage errors pose a distinct challenge to quantum control relative to the more well-studied decoherence errors and can be a limiting factor to achieving fault-tolerant quantum computation. Here we present scalable and robust randomized benchmarking protocols for quickly estimating the rates of both coherent and incoherent leakage, allowing for practical minimization of the leakage rate by varying over control methods. We illustrate the reliability of the protocol through numerical simulations with physically-relevant error models.