Error-corrected quantum annealing with hundreds of qubits

Area of Science:

• Quantum Computing
• Quantum Information Science
• Condensed Matter Physics

Background:

• Quantum computing promises speedups but is vulnerable to decoherence, which degrades quantum states.
• Quantum error correction is crucial for fault-tolerant quantum computation.
• Protection against decoherence in quantum annealing, used for optimization problems, is not well understood.

Purpose of the Study:

• To develop and experimentally demonstrate quantum error correction specifically for quantum annealing.
• To assess the effectiveness of this error correction in mitigating decoherence.
• To explore the potential for noise-protected adiabatic quantum optimization.

Main Methods:

• Developed a novel quantum error correction scheme tailored for quantum annealing.
• Experimentally implemented the error correction using antiferromagnetic chains with up to 344 superconducting flux qubits.
• Utilized processors capable of programmable quantum annealing.

Main Results:

• Demonstrated a substantial performance improvement in quantum annealing processors with error correction compared to those without.
• Successfully protected quantum information against decoherence in a quantum annealing system.
• Provided experimental evidence for the efficacy of quantum error correction in this paradigm.

Conclusions:

• The developed error correction is effective for quantum annealing, paving the way for large-scale noise-protected adiabatic quantum optimization.
• Significant progress has been made in protecting quantum annealing from decoherence.
• A universal threshold theorem for quantum annealing, analogous to the circuit model, remains an open research question.