Quantum Rabi Models | 李梓民 Zi-Min Li

Ultrastrong Light-Matter Coupling

Tue, 01 Sep 2026 00:00:00 +0000

The quantum Rabi model is a fundamental description of a two-level system interacting with a quantized bosonic mode. We develop exact and physically transparent approximate methods for Rabi-type models, investigate exceptional solutions and conical intersections, and study how hidden symmetries emerge when conventional parity symmetry is broken.

Our work spans Rabi and Dicke models, hidden symmetry, tunneling dynamics, and geometric phases. Generalized adiabatic approximations and variational approaches connect analytical structure with experimentally relevant regimes of ultrastrong coupling.

Representative publications include Hidden symmetry and tunneling dynamics (2021) and Generalized adiabatic approximation (2021).

Entanglement and Bell-State Preparation in the Tripartite Quantum Rabi Model

Sat, 11 Jul 2026 00:00:00 +0000

How can a simple light-matter interaction reorganize two-qubit entanglement, and can that structure be used to prepare a useful quantum state? Our recent preprint studies these questions in the tripartite quantum Rabi model, where two qubits interact collectively with a single bosonic mode.

In the zero-detuning limit, the spectrum separates into branches with sharply different entanglement properties. Some triplet states carry no two-qubit entanglement, while others are maximally entangled; the antisymmetric singlet ladder remains decoupled. Finite detuning turns selected crossings into avoided crossings, allowing entanglement to move between eigenbranches.

This spectral picture suggests a state-preparation strategy. Starting from a nearly separable state at weak coupling, one can slowly increase the collective coupling and follow an eigenbranch that becomes dominated by a Bell-state component. A compact three-state model explains the relevant mixing, while finite-time simulations identify the coupling strength and ramp duration needed for high final fidelity.

The work links a static question, the organization of entanglement in the spectrum, to a dynamical one, the preparation of a Bell state within a finite time.

Read the preprint on arXiv

Static Entanglement Structure and Adiabatic Bell-State Preparation in the Tripartite Quantum Rabi Model

Sat, 11 Jul 2026 00:00:00 +0000