Tavis-Cummings model beyond the rotating wave approximation: Quasidegenerate qubits

S. Agarwal, S. M.Hashemi Rafsanjani, J. H. Eberly

Research output: Contribution to journalArticlepeer-review

66 Scopus citations


The Tavis-Cummings model for more than one qubit interacting with a common oscillator mode is extended beyond the rotating wave approximation (RWA). We explore the parameter regime in which the frequencies of the qubits are much smaller than the oscillator frequency and the coupling strength is allowed to be ultrastrong. The application of the adiabatic approximation introduced by Irish for a single-qubit system is extended to the multiqubit case. For a two-qubit system, we identify three-state manifolds of close-lying dressed energy levels and obtain results for the dynamics of intramanifold transitions that are incompatible with results from the familiar regime of the RWA. We exhibit features of two-qubit dynamics that are different from the single-qubit case, including calculations of qubit-qubit entanglement. Both number state and coherent state preparations are considered, and we derive analytical formulas that simplify the interpretation of numerical calculations. Expressions for individual collapse and revival signals of both population and entanglement are derived.

Original languageEnglish (US)
Article number043815
JournalPhysical Review A - Atomic, Molecular, and Optical Physics
Issue number4
StatePublished - Apr 10 2012
Externally publishedYes

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics


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