Ultrastrong coupling in two-resonator circuit QED
Journal article, 2016

We report on ultrastrong coupling between a superconducting flux qubit and a resonant mode of a system comprised of two superconducting coplanar stripline resonators coupled galvanically to the qubit. With a coupling strength as high as 17.5% of the mode frequency, exceeding that of previous circuit quantum electrodynamics experiments, we observe a pronounced Bloch-Siegert shift. The spectroscopic response of our multimode system reveals a clear breakdown of the Jaynes-Cummings approximation. In contrast to earlier experiments, the high coupling strength is achieved without making use of an additional inductance provided by a Josephson junction.
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Published in

Physical Review B

24699950 (ISSN) 24699969 (eISSN)

Vol. 93 Issue 21 p. Art. no. 214501- art. no 214501

Research Project(s)

Scalable Superconducting Processors for Entangled Quantum Information Technology (ScaleQIT)

European Commission (EC) (EC/FP7/600927), 2013-02-01 -- 2016-01-31.

Quantum Propagating Microwaves in Strongly Coupled Environments (PROMISCE)

European Commission (EC) (EC/FP7/284566), 2012-04-01 -- 2015-03-31.

Categorizing

Subject Categories (SSIF 2011)

Atom and Molecular Physics and Optics

Identifiers

DOI

10.1103/PhysRevB.93.214501

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3/9/2025 1