Quantum circuit analog of the dynamical Casimir effect

Toshiyuki Fujii*, Shigemasa Matsuo, Noriyuki Hatakenaka, Susumu Kurihara, Anton Zeilinger

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    52 Citations (Scopus)


    We investigate a quantum-circuit analog of the dynamical Casimir effect discussed in cavity quantum electrodynamics (QED). A double superconducting quantum interference device (SQUID), consisting of a superconducting loop interrupted by a dc-SQUID, is regarded as a harmonic oscillator with a time-dependent frequency imitating the nonadiabatic boundaries in a cavity QED. Squeezing occurs due to parametric processes inherent in the system. We reformulate squeezing based on the Bogoliubov transformation between eigenstates at different times and derive the analytic formula for quantum-state evolutions of the system. The squeezing parameter clearly reveals the relationship between squeezing and nonadiabatic nature of the system. Thus, the squeezing parameter serves as a measure for the dynamical Casimir effect. We demonstrate squeezing for two types of frequency modulation and propose a method for measuring squeezing by using a circuit QED technique under coherent oscillations between an artificial atom and an LC circuit in the presence of dissipation. These observations suggest that a quantum circuit with a Josephson junction is a promising candidate for detecting the dynamical Casimir effect.

    Original languageEnglish
    Article number174521
    JournalPhysical Review B - Condensed Matter and Materials Physics
    Issue number17
    Publication statusPublished - 2011 Nov 23

    ASJC Scopus subject areas

    • Condensed Matter Physics
    • Electronic, Optical and Magnetic Materials


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