Suppressing relaxation in superconducting qubits by quasiparticle pumping.

Area of Science:

• Quantum Computing
• Quantum Error Correction
• Superconducting Qubits

Background:

• Dynamical error suppression techniques are standard for improving quantum system coherence.
• These methods mitigate dephasing errors by reversing environmental noise-induced evolution.
• However, they are ineffective against irreversible processes like energy relaxation.

Purpose of the Study:

• To investigate a complementary, stochastic approach for reducing quantum errors.
• To explore shaping the noise environment dynamically using control pulses.
• To address limitations of deterministic error suppression in quantum systems.

Main Methods:

• Implemented a control pulse pumping sequence on superconducting qubits.
• Targeted the reduction of unpaired electrons (quasiparticles) near the device.
• Quantified the impact of quasiparticle density reduction on qubit performance.

Main Results:

• Achieved a 70% reduction in quasiparticle density.
• Observed a threefold enhancement in qubit relaxation times.
• Demonstrated a comparable reduction in coherence variability.

Conclusions:

• Shaping the noise environment dynamically is a viable strategy for quantum error reduction.
• This stochastic approach complements deterministic error suppression methods.
• Reduced quasiparticle density significantly improves coherence and relaxation times in superconducting qubits.