Thermalization and criticality on an analogue-digital quantum simulator

Area of Science:

• Quantum Simulation
• Condensed Matter Physics
• Quantum Information Science

Background:

• Approaching thermal equilibrium in interacting quantum systems is a key challenge.
• Quantum simulators require flexible state preparation, precise evolution, and detailed characterization.
• Previous simulators lacked versatility in measurement and control.

Purpose of the Study:

• To present a novel superconducting quantum simulator with hybrid analogue-digital capabilities.
• To explore thermalization dynamics and phase transitions beyond classical simulation limits.
• To demonstrate advanced state preparation and measurement for studying quantum phenomena.

Main Methods:

• Development of a 69-qubit superconducting quantum processor.
• Implementation of universal quantum gates and high-fidelity analogue evolution.
• Utilizing versatile measurement capabilities for state characterization.
• Performing cross-entropy benchmarking experiments.

Main Results:

• Quantum simulator performance exceeded classical simulation capabilities.
• Observed breakdown of Kibble-Zurek scaling in the XY model due to coarsening.
• Identified signatures of the classical Kosterlitz-Thouless phase transition.
• Demonstrated precise energy control for studying the eigenstate thermalization hypothesis.
• Showcased digital preparation of entangled states and imaging of energy/vorticity transport.

Conclusions:

• The hybrid analogue-digital quantum processor is effective for state preparation across many-body spectra.
• The platform successfully unveils thermalization dynamics.
• This work advances the potential of quantum simulators for fundamental physics research.