Superradiant Topological Peierls Insulator inside an Optical Cavity

Area of Science:

• Quantum optics
• Condensed matter physics
• Ultracold atomic gases

Background:

• Ultracold Fermi gases confined in optical resonators exhibit self-ordering transitions.
• This transition involves breaking Z2 symmetry and collective scattering of pump photons into the cavity.
• The phenomenon is typically observed when the laser is red-detuned to an atomic transition.

Purpose of the Study:

• To investigate the self-ordering transition in ultracold Fermi gases with blue-detuned laser light.
• To explore the topological properties of the emergent superradiant optical lattice.
• To identify methods for nondestructively observing these topological features.

Main Methods:

• Theoretical analysis of a spinless ultracold Fermi gas in an optical resonator.
• Considering transverse laser illumination blue-detuned to an atomic transition.
• Analyzing the resulting superradiant optical lattice and its Bloch bands.

Main Results:

• The self-ordering transition occurs for blue-detuned light, forming a homopolar superradiant optical lattice.
• The lattice exhibits two distinct dimerizations, leading to nontrivial topological structures (non-zero Zak phase).
• A Peierls-like instability creates a topological insulator with edge states when Fermi momentum is near half the cavity-mode wave number.

Conclusions:

• The study demonstrates the emergence of topological phases in a driven-dissipative ultracold atomic system.
• Topological features, including Zak phase and edge states, can be nondestructively probed via cavity output spectrum.
• This work opens avenues for exploring topological physics in controllable quantum many-body systems.