Tunable Plasmonic Ultrastrong Coupling: Emulating Dicke Physics at Room Temperature

TL;DR

This paper demonstrates tunable plasmonic ultrastrong coupling in a terahertz metasurface, emulating Dicke physics at room temperature by enhancing light-matter interactions through cooperative effects in meta-atom arrays.

Contribution

It extends Dicke cooperativity to plasmonic metasurfaces, achieving ultrastrong coupling and room-temperature quantum emulation with engineered meta-atoms.

Findings

Observation of anticrossing behavior indicating strong coupling

Enhancement of coupling rate into the ultrastrong regime by N^0.5

Room-temperature quantum emulation of giant dipole moment qubits

Abstract

A system of N two-level atoms cooperatively interacting with a photonic field can be described as a single giant atom coupled to the field with interaction strength ~N^0.5. This enhancement, known as Dicke cooperativity in quantum optics, has recently become an indispensable element in quantum information technology based on strong light-matter coupling. Here, we extend the coupling beyond the standard light-matter interaction paradigm, emulating Dicke cooperativity in a terahertz metasurface with N meta-atoms. Cooperative enhancement manifested in the form of matter-matter coupling, through the hybridization of localized surface plasmon resonance in individual meta-atoms and surface lattice resonance due to the periodic array of the meta-atoms. By varying the lattice constant of the array, we observe a clear anticrossing behavior, a signature of strong coupling. Furthermore, through engineering of the capacitive split-gap in the meta-atoms, the coupling rate was cooperatively enhanced into the ultrastrong coupling regime by a factor of N^0.5. This room-temperature technology serves as a convenient quantum emulator of the dynamics of a qubit with a giant dipole moment coherently driven by a single bosonic field.