Dynamically Induced Symmetry Breaking and Out-of-Equilibrium Topology in a 1D Quantum System

Area of Science:

• Condensed Matter Physics
• Quantum Simulation
• Topological Matter

Background:

• Topological phases of matter are characterized by invariants derived from wave functions.
• The Zak phase is a key invariant for one-dimensional (1D) lattices.
• Understanding symmetry properties in topological systems is crucial for their characterization.

Purpose of the Study:

• To experimentally investigate topological invariants in a 1D bipartite Rice-Mele (RM) lattice.
• To study the time evolution of the Zak phase and chiral winding number under symmetry changes.
• To explore dynamical symmetry breaking and restoration in quantum systems.

Main Methods:

• Realization of the 1D Rice-Mele lattice using ultracold 87Rb atoms.
• Employing quantum state tomography to track topological invariants.
• Implementing diabatic parameter tuning to control lattice configurations and symmetries.
• Performing quantum quenches between different lattice configurations.

Main Results:

• The Zak phase evolves continuously during quenches.
• The chiral winding number becomes well-defined and can attain any integer value when chiral symmetry transiently appears out-of-equilibrium.
• Dynamically induced symmetry breaking and periodic restoration of chiral symmetry were confirmed.
• Winding numbers changed by ±2 during quenches between configurations with identical symmetries, leading to values not present in the native RM Hamiltonian.

Conclusions:

• Experimental control over topological invariants is achievable in ultracold atom systems.
• Out-of-equilibrium dynamics can lead to novel topological phenomena, including the emergence of well-defined winding numbers.
• The study confirms theoretical predictions of dynamically induced symmetry breaking and highlights the rich behavior of topological systems under non-equilibrium conditions.