Observation of critical phase transition in a generalized Aubry-Andr\'e-Harper model on a superconducting quantum processor with tunable couplers

TL;DR

This study uses a programmable superconducting quantum processor to simulate a generalized Aubry-Andre9-Harper model, observing phase transitions among extended, localized, and critical phases through quantum dynamics and participation entropy measurements.

Contribution

It demonstrates the first experimental simulation of a generalized Aubry-Andre9-Harper model with tunable couplers, enabling exploration of complex quantum phases and transitions.

Findings

Observation of critical phase transition in a quantum simulator

Measurement of spin transport across different phases

Extension of quantum simulation capabilities with tunable couplers

Abstract

Quantum simulation enables study of many-body systems in non-equilibrium by mapping to a controllable quantum system, providing a new tool for computational intractable problems. Here, using a programmable quantum processor with a chain of 10 superconducting qubits interacted through tunable couplers, we simulate the one-dimensional generalized Aubry-Andr\'e-Harper model for three different phases, i.e., extended, localized and critical phases. The properties of phase transitions and many-body dynamics are studied in the presence of quasi-periodic modulations for both off-diagonal hopping coefficients and on-site potentials of the model controlled respectively by adjusting strength of couplings and qubit frequencies. We observe the spin transport for initial single- and multi-excitation states in different phases, and characterize phase transitions by experimentally measuring dynamics of participation entropies. Our experimental results demonstrate that the newly developed tunable coupling architecture of superconducting processor extends greatly the simulation realms for a wide variety of Hamiltonians, and may trigger further investigations on various quantum and topological phenomena.