Controlling higher-orbital quantum phases of ultracold atoms via coupling to optical cavities

TL;DR

This paper demonstrates how coupling ultracold bosonic gases to optical cavities enables control over higher-orbital quantum phases, leading to the formation of novel superfluid and Mott-insulating states with orbital-density waves.

Contribution

It introduces a method to selectively transfer atoms to higher orbitals using cavity coupling and demonstrates the emergence of stable higher-orbital phases in a controlled setting.

Findings

Atoms can be transferred to p- or d-orbitals by tuning the pump laser reflection.

Cavity interactions induce self-organization into higher-orbital superfluid and Mott-insulating phases.

Orbital-density waves emerge due to cavity-induced orbital-flip processes.

Abstract

Orbital degree of freedom plays an important role in understanding exotic phenomena of strongly correlated materials. We study strongly correlated ultracold bosonic gases coupled to a high-finesse cavity, pumped by a blue-detuned laser in the transverse direction. Based on an extended Bose-Hubbard model with parameters adapted to recent experiments, we find that by tuning the reflection of pump laser, atoms can be selectively transferred to the odd-parity $p$-orbital, or to even-parity $d$-orbital band of a two-dimensional square lattice, accompanied with cavity-photon excitations. By interacting with cavity field, atoms self-organize to form stable higher-orbital superfluid and Mott-insulating phases with orbital-density waves, as a result of cavity induced orbital-flip processes. Our study opens the route to manipulate orbital degrees of freedom in strongly correlated quantum gases via coupling to optical cavities.