Floquet-engineered Emergent Massive Nambu-Goldstone Modes

TL;DR

This paper introduces a framework for creating massive Nambu-Goldstone modes in driven many-body systems by exploiting Lie group structures, with potential experimental realizations and methods to verify their existence.

Contribution

It presents a novel approach to engineer massive Nambu-Goldstone modes via explicit symmetry breaking in driven systems, supported by protocols for experimental certification.

Findings

Mass gap scales linearly with drive period.

Explicit realizations in spin models support gapped excitations.

Protocol for certifying massive Nambu-Goldstone modes from dynamics.

Abstract

We present a general framework to implement massive Nambu-Goldstone quasi-particles in driven many-body systems. The underlying mechanism leverages an explicit Lie group structure imprinted into an effective Hamiltonian that governs the dynamics of slow degrees of freedom; the resulting emergent continuous symmetry is weakly explicitly broken, giving rise to a massive Nambu-Goldstone mode, with a spectral mass gap scaling linearly with the drive period. We discuss explicit and experimentally implementable realizations, such as Heisenberg-like spin models that support gapped spin-wave excitations. We provide a protocol to certify the existence of the massive Nambu-Goldstone mode from the dynamics of specific observables, and analyse the dispersion spectrum and their lifetime in the presence of weak explicit symmetry breaking.