Fast Flux-Activated Leakage Reduction for Superconducting Quantum Circuits

Area of Science:

• Quantum Computing
• Quantum Error Correction

Background:

• Quantum computers need quantum error correction for low error rates.
• Qubit leakage is a major error source in quantum error correction codes.
• Superconducting qubits are a leading platform for quantum computation.

Purpose of the Study:

• To present a resource-efficient universal leakage reduction unit for superconducting qubits.
• To mitigate errors caused by leakage out of the computational subspace.

Main Methods:

• Utilized parametric flux modulation for leakage reduction.
• Implemented a universal leakage reduction unit.
• Applied the unit in repeated weight-two stabilizer measurements.

Main Results:

• Achieved leakage reduction down to 7x10^-4 in ~50 ns.
• Demonstrated low computational subspace error of 2.5(1)x10^-3.
• Reduced total detected errors scalably in stabilizer measurements.

Conclusions:

• The developed leakage reduction unit is efficient and comparable to single-qubit gates.
• This method is applicable to both auxiliary and data qubits without extra hardware.
• The approach is attractive for large-scale quantum error correction and fault-tolerant quantum computation.