Spectrum of the Dicke model in a superconducting qubit-oscillator system

Sahel Ashhab, Y. Matsuzaki, K. Kakuyanagi, S. Saito, F. Yoshihara, T. Fuse, K. Semba

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Abstract

We calculate the transmission spectrum of a superconducting circuit realization of the Dicke model and identify spectroscopic features that can serve as signatures of the superradiant phase. In particular, we calculate the resonance frequencies of the system as functions of the bias term, which is usually absent in studies on the Dicke model but is commonly present in superconducting qubit circuits. To avoid over-complicating the proposed circuit, we assume a fixed coupling strength. This situation precludes the possibility of observing signatures of the phase transition by varying the coupling strength across the critical point. We show that the spectrum obtained by varying the bias point under fixed coupling strength can contain signatures of the normal and superradiant phases: in the normal phase one expects to observe two spectral lines, while in the superradiant phase four spectral lines are expected to exist close to the qubits' symmetry point. Provided that parameter fluctuations and decoherence rates are sufficiently small, the four spectral lines should be observable and can serve as a signature of the superradiant phase.

Original languageEnglish
Article number063822
JournalPhysical Review A
Volume99
Issue number6
DOIs
Publication statusPublished - 18 Jun 2019

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ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

Cite this

Ashhab, S., Matsuzaki, Y., Kakuyanagi, K., Saito, S., Yoshihara, F., Fuse, T., & Semba, K. (2019). Spectrum of the Dicke model in a superconducting qubit-oscillator system. Physical Review A, 99(6), [063822]. https://doi.org/10.1103/PhysRevA.99.063822