Ultrastrong coupling regime of cavity QED with phase-biased flux qubits

2009/06/30 by Jérôme Bourassa, J. Bourassa, J. M. Gambetta +9 · 4 citations
Computer Science · Physics and Astronomy · #Condensed matter physics #Coplanar waveguide #Coupling (piping) #Flux qubit #Inductance #Kinetic inductance #Mechanical and Optical Resonators #Microwave #Optoelectronics #Phase qubit #Physics #Quantum Information and Cryptography #Quantum and electron transport phenomena #Quantum electrodynamics #Quantum mechanics #Qubit #Resonator #Superconductivity #Voltage #cond-mat.mes-hall #quant-ph

paper · pdf · doi:10.1103/physreva.80.032109

published as Phys. Rev. A 80, 032109 (2009) · 9 pages, 7 figures. Published version with minor changes and corrections

openalex publication_date 2009/09/15 · arxiv created 2009/09/16 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05

Abstract

We theoretically study a circuit QED architecture based on a superconducting flux qubit directly coupled to the center conductor of a coplanar waveguide transmission-line resonator. As already shown experimentally [A. A. Abdumalikov, Jr. et al., Phys. Rev. B 78, 180502(R) (2008)], the strong coupling regime of cavity QED can readily be achieved by optimizing the local inductance of the resonator in the vicinity of the qubit. In addition to yielding stronger coupling with respect to other proposals for flux qubit based circuit QED, this approach leads to a qubit-resonator coupling strength g which does not scale as the area of the qubit but is proportional to the total inductance shared between the resonator and the qubit. Strong coupling can thus be attained while still minimizing sensitivity to flux noise. Finally, we show that by taking advantage of the large kinetic inductance of a Josephson junction in the center conductor of the resonator can lead to coupling energies of several tens of percent of the resonator frequency, reaching the ultrastrong coupling regime of cavity QED where the rotating-wave approximation breaks down. This should allow an on-chip implementation of the E\ensuremath\bigotimes\ensuremathβ Jahn-Teller model.

Citations

• Charge insensitive qubit design derived from the Cooper pair box
• Coherent Quantum Dynamics of a Superconducting Flux Qubit
• Input-output theory of cavities in the ultrastrong coupling regime: The case of time-independent cavity parameters
• n-qubit-controlled phase gate with superconducting quantum-interference devices coupled to a resonator
• Circuit QED with a flux qubit strongly coupled to a coplanar transmission line resonator
• Stability of polyatomic molecules in degenerate electronic states - I—Orbital degeneracy

Cited by

• Microwave photonics with Josephson junction arrays: Negative refraction index and entanglement through disorder
• Entanglement dynamics of the ultrastrong-coupling three-qubit Dicke model
• Ultrastrong coupling of a single artificial atom to an electromagnetic continuum in the nonperturbative regime
• The quantum Rabi model for two qubits