Prethermalization by random multipolar driving on a 78-qubit processor

Area of Science:

• Quantum simulation
• Non-equilibrium many-body physics
• Quantum information science

Background:

• Time-dependent drives enable exploration of exotic non-equilibrium phenomena.
• Drive-induced heating typically destabilizes quantum systems.
• Periodic (Floquet) drives can suppress heating in the high-frequency regime.

Purpose of the Study:

• Investigate heating suppression in non-periodically driven quantum systems.
• Experimentally observe and characterize prethermal phases.
• Explore the tunability and scaling laws of prethermal lifetimes.

Main Methods:

• Utilized a 78-qubit superconducting quantum processor (Chuang-tzu 2.0).
• Employed structured random protocols with tunable heating rates.
• Measured particle imbalance and subsystem entanglement entropy over 1,000 driving cycles.
• Performed quantum-state tomography on different subsystems.

Main Results:

• Observed long-lived prethermal phases and a prethermal plateau.
• Demonstrated 'doubly tunable' prethermal lifetime (by frequency and multipolar order).
• Found algebraic growth of prethermal lifetime with frequency, following universal scaling exponent 2n+1.
• Observed non-uniform spatial entanglement and a crossover from area- to volume-law scaling.
• Studied dynamics beyond classical simulation capabilities.

Conclusions:

• Superconducting quantum processors are powerful platforms for studying non-equilibrium physics.
• The observed phenomena and scaling laws are relevant for understanding driven quantum systems.
• This work opens avenues for exploring universal scaling laws in complex quantum regimes.