Microwave Spectroscopy of a Cooper-Pair Transistor Coupled to a Lumped-Element Resonator

Abstract

We have studied the microwave response of a single Cooper-pair transistor (CPT) coupled to a lumped-element microwave resonator. The resonance frequency of this circuit, $f_r$, was measured as a function of the charge $n_g$ induced on the CPT island by the gate electrode, and the phase difference across the CPT, ${\varphi }_B$, which was controlled by the magnetic flux in the superconducting loop containing the CPT. The observed $f_r(n_g,{\varphi }_B)$ dependences reflect the variations of the CPT Josephson inductance with $n_g$ and ${\varphi }_B$ as well as the CPT excitation when the microwaves induce transitions between different quantum states of the CPT. The results are in excellent agreement with our simulations based on the numerical diagonalization of the circuit Hamiltonian. This agreement over the whole range of $n_g$ and ${\varphi }_B$ is unexpected, because the relevant energies vary widely, from 0.1K to 3K. The observed strong dependence $f_r(n_g,{\varphi }_B)$ near the resonance excitation of the CPT provides a tool for sensitive charge measurements.

10 pages, 6 figures

References in corpus (5)

• Approaching Unit Visibility for Control of a Superconducting Qubit with Dispersive Readout
• Loss and decoherence due to stray infrared light in superconducting quantum circuits
• Time-domain measurements of quasiparticle tunneling rates in a single-Cooper-pair transistor
• Reading-out the state inductively and microwave spectroscopy of an interferometer-type charge qubit
• Voltage-Current curves for small Josephson junction arrays

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• Josephson Metamaterial with a widely tunable positive/negative Kerr constant
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• A Nonlinear Charge- and Flux-Tunable Cavity Derived from an Embedded Cooper Pair Transistor
• Fast and Ultrasensitive Electrometer Operating at the Single-Photon Level
• Green functions of interacting systems in the strongly localized regime
• Magnetic Field Driven Quantum Phase Transitions in Josephson Arrays