Fault-tolerant quantum error detection

TL;DR

This paper demonstrates the encoding and syndrome measurement of a fault-tolerant logical qubit using four trapped atomic ions, showing robustness against operational imperfections and errors, which is crucial for scalable quantum computing.

Contribution

First experimental implementation of fault-tolerant logical qubit encoding and error detection with trapped ions, validating robustness against operational errors.

Findings

Successful syndrome measurement of a fault-tolerant logical qubit

Robustness of the encoded qubit against operational imperfections

Persistence of error detection advantage despite high error rates

Abstract

Quantum computers will eventually reach a size at which quantum error correction becomes imperative. Quantum information can be protected from qubit imperfections and flawed control operations by encoding a single logical qubit in multiple physical qubits. This redundancy allows the extraction of error syndromes and the subsequent detection or correction of errors without destroying the logical state itself through direct measurement. Here we show the encoding and syndrome measurement of a fault-tolerant logical qubit via an error detection protocol on four physical qubits, represented by trapped atomic ions. This demonstrates for the first time the robustness of a fault-tolerant qubit to imperfections in the very operations used to encode it. The advantage persists in the face of large added error rates and experimental calibration errors.