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Fault-tolerant control of an error-corrected qubit
Laird Egan1,2,3, Dripto M Debroy4,5, Crystal Noel6,7
1Joint Quantum Institute, Center for Quantum Information and Computer Science, University of Maryland, College Park, MD, USA. laird.egan@gmail.com.
Nature
|October 5, 2021
Summary
Fault-tolerant circuits were demonstrated in a real quantum system, significantly reducing errors. This breakthrough enables more accurate quantum computations and paves the way for robust quantum computing.
Area of Science:
- Quantum Information Science
- Experimental Quantum Computing
- Quantum Error Correction
Background:
- Quantum error correction encodes information into larger systems to protect it from noise.
- Controlling encoded qubits increases complexity, necessitating fault-tolerant circuits.
- Previous demonstrations of fault-tolerant circuits lacked real-world quantum system noise.
Purpose of the Study:
- To experimentally demonstrate fault-tolerant circuits in an error-corrected physical system.
- To assess the effectiveness of fault-tolerant protocols against native noise characteristics.
- To establish the feasibility of accurate logical qubit operations.
Main Methods:
- Utilized 13 trapped ion qubits to implement fault-tolerant circuits.
- Developed and tested protocols for preparation, measurement, rotation, and stabilizer measurement of a Bacon-Shor logical qubit.
- Compared fault-tolerant protocols against non-fault-tolerant ones under realistic noise conditions.
Main Results:
- Achieved significant reductions in error rates for logical primitives compared to non-fault-tolerant methods.
- Obtained an average state preparation and measurement error of 0.6% and Clifford gate error of 0.3% after error correction.
- Prepared magic states with fidelities surpassing the distillation threshold, demonstrating key single-qubit fault-tolerant control elements.
Conclusions:
- Fault-tolerant circuits enable highly accurate logical operations in current quantum systems.
- The experimental demonstration validates the practical application of fault-tolerant design principles.
- Further improvements in two-qubit gates and intermediate measurements could lead to stabilized logical qubits.
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