Characterization of quantum dynamics using quantum error correction

TL;DR

This paper introduces a novel method for characterizing quantum noise processes using quantum error correction, enabling concurrent noise characterization and correction with fewer configurations.

Contribution

The authors propose a quantum error correction-based approach for characterizing quantum dynamics that operates concurrently with quantum processes, reducing the number of configurations needed.

Findings

Requires at most 2(4^n - 1) configurations for n qubits

Uses stabilizer measurements and syndrome analysis for noise characterization

Allows concurrent noise characterization and correction

Abstract

Characterizing noisy quantum processes is important to quantum computation and communication (QCC), since quantum systems are generally open. To date, all methods of characterization of quantum dynamics (CQD), typically implemented by quantum process tomography, are \textit{off-line}, i.e., QCC and CQD are not concurrent, as they require distinct state preparations. Here we introduce a method, "quantum error correction based characterization of dynamics", in which the initial state is any element from the code space of a quantum error correcting code that can protect the state from arbitrary errors acting on the subsystem subjected to the unknown dynamics. The statistics of stabilizer measurements, with possible unitary pre-processing operations, are used to characterize the noise, while the observed syndrome can be used to correct the noisy state. Our method requires at most $2(4^n-1)$ configurations to characterize arbitrary noise acting on $n$ qubits.