Multimode mediated qubit-qubit coupling and dark-state symmetries in circuit quantum electrodynamics Journal Article


Author(s): Filipp, Stefan; Göppl, M; Fink, Johannes; Baur, Matthias P; Bianchetti, R; Steffen, L. Kraig; Wallraff, Andreas
Article Title: Multimode mediated qubit-qubit coupling and dark-state symmetries in circuit quantum electrodynamics
Affiliation
Abstract: Microwave cavities with high quality factors enable coherent coupling of distant quantum systems. Virtual photons lead to a transverse interaction between qubits when they are nonresonant with the cavity but resonant with each other. We experimentally investigate the inverse scaling of the interqubit coupling with the detuning from a cavity mode and its proportionality to the qubit-cavity interaction strength. We demonstrate that the enhanced coupling at higher frequencies is mediated by multiple higher-harmonic cavity modes. Moreover, we observe dark states of the coupled qubit-qubit system and analyze their relation to the symmetry of the applied driving field at different frequencies.
Keywords: QUANTUM ELECTRODYNAMICS; Nonresonant; dark state; Quantum optics; Quantum electronics; Cavity mode; Coherent coupling; Detunings; Driving field; High quality factors; Higher frequencies; Interaction strength; Interqubit couplings; Microwave cavity; Multimodes; Quantum system; Virtual photons; Electrodynamics
Journal Title: Physical Review A - Atomic, Molecular, and Optical Physics
Volume: 83
Issue 6
ISSN: 1094-1622
Publisher: American Physical Society  
Date Published: 2011-06-22
Start Page: Article number 063827
Sponsor: This work was supported by the Swiss National Science Foundation (SNF), the Austrian Science Foundation (FWF), and ETH Zurich
DOI: 10.1103/PhysRevA.83.063827
Open access: no