Dynamical symmetries of periodically-driven quantum systems and their spectroscopic signatures

TL;DR

This paper explores how dynamical symmetries in periodically-driven quantum systems influence spectroscopic phenomena, revealing new effects like symmetry-protected dark states and transparency in the strong light-matter coupling regime.

Contribution

It introduces a framework for understanding dynamical symmetries in Floquet systems and predicts novel spectroscopic signatures arising from these symmetries.

Findings

Dynamical rotational symmetry leads to dark state conditions and selection rules.

Particle-hole symmetry causes dark states and transparency at quasienergy crossings.

Chiral and time-reversal symmetries can combine with particle-hole symmetry to produce specific effects.

Abstract

Spatial symmetries of quantum systems leads to important effects in spectroscopy, such as selection rules and dark states. Motivated by the increasing strength of light-matter interaction achieved in recent experiments, we investigate a set of dynamically-generalized symmetries for quantum systems, which are subject to a strong periodic driving. Based on Floquet response theory, we study rotational, particle-hole, chiral and time-reversal symmetries and their signatures in spectroscopy, including symmetry-protected dark states (spDS), a Floquet band selection rule (FBSR), and symmetry-induced transparency (siT). Specifically, a dynamical rotational symmetry establishes dark state conditions, as well as selection rules for inelastic light scattering processes; a particle-hole symmetry introduces dark states for symmetry related Floquet states and also a transparency effect at quasienergy crossings; chiral symmetry and time-reversal symmetry alone do not imply dark state conditions, but can be combined to the particle-hole symmetry. Our predictions reveal new physical phenomena when a quantum system reaches the strong light-matter coupling regime, important for superconducting qubits, atoms and molecules in optical or plasmonic field cavities, and optomechanical systems.