Tunable Coupler for Mediating Interactions between a Two-Level System and a Waveguide from a Decoupled State to the Ultra-Strong Coupling Regime

Abstract

Two-level systems (TLS) coupled to waveguides are a fundamental paradigm for light-matter interactions and quantum networks. We introduce and experimentally demonstrate a method to tune the interaction between a TLS, implemented as a flux qubit, and a transmission line waveguide from a decoupled state to a coupling strength that is a significant fraction of the TLS transition frequency, near the ultra-strong coupling regime. The coupling, controlled via magnetic flux, is described by a normalized coupling strength $\alpha$ that is measured to range between $6.2\times 10^{-5}$ and $2.19\times 10^{-2}$, with larger attainable maximum values predicted by a circuit model of the device. This system enables future investigations in the dynamics of the spin-boson model, microwave photonics, and relativistic quantum information.

Main: 14 pages, 10 figures

References in corpus (5)

• Generating Single Microwave Photons in a Circuit
• Controllable coupling of superconducting flux qubits
• Quasiparticle relaxation of superconducting qubits in the presence of flux
• On-demand microwave generator of shaped single photons
• Mediated tunable coupling of flux qubits

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