Polaritonic Ultrastrong Coupling: Quantum Entanglement in Ground State

Abstract

The ultrastrong coupling between the elementary excitations of matter and microcavity modes is studied in a fully analytical quantum-mechanical theoretical framework. The elementary excitation could be phonons, excitons, plasmons, etc. From the diagonalization of the Hamiltonian, we obtain the ground state of the polariton Hamiltonian. The ground state belongs to the Gaussian class. Using the Gaussian property we calculate the quantum entanglement in the ground state. We use two different measures for quantum entanglement -- entanglement entropy and the logarithmic negativity parameter and obtain rather simple analytical expressions for the entanglement measures. Our findings show that the amount of quantum entanglement in the ground state is quite significant in the ultrastrong coupling regime. It can be obtained from the measurement of the polariton frequencies.

References in corpus (4)

• Strong light-matter coupling in two-dimensional atomic crystals
• Hybridizing ferromagnetic magnons and microwave photons in the quantum limit
• Microcavity phonon polaritons from weak to ultrastrong phonon-photon coupling
• Probing the spectrum of the Jaynes-Cummings-Rabi model by its isomorphism to an atom inside a parametric amplifier cavity

Cited by in corpus (2)

• Reconciling quantum and classical spectral theories of ultrastrong coupling: Role of cavity bath coupling and gauge corrections
• Direct space-time modeling of mechanically dressed dipole-dipole interactions with electromagnetically-coupled oscillating dipoles