Single-shot qubit readout in circuit Quantum Electrodynamics

Abstract

The future development of quantum information using superconducting circuits requires Josephson qubits [1] with long coherence times combined to a high-fidelity readout. Major progress in the control of coherence has recently been achieved using circuit quantum electrodynamics (cQED) architectures [2, 3], where the qubit is embedded in a coplanar waveguide resonator (CPWR) which both provides a well controlled electromagnetic environment and serves as qubit readout. In particular a new qubit design, the transmon, yields reproducibly long coherence times [4, 5]. However, a high-fidelity single-shot readout of the transmon, highly desirable for running simple quantum algorithms or measur- ing quantum correlations in multi-qubit experiments, is still lacking. In this work, we demonstrate a new transmon circuit where the CPWR is turned into a sample-and-hold detector, namely a Josephson Bifurcation Amplifer (JBA) [6, 7], which allows both fast measurement and single-shot discrimination of the qubit states. We report Rabi oscillations with a high visibility of 94% together with dephasing and relaxation times longer than 0:5 μ\s. By performing two subsequent measurements, we also demonstrate that this new readout does not induce extra qubit relaxation.

14 pages including 4 figures, preprint format

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Cited by in corpus (10)

• Opto-mechanical transducers for long-distance quantum communication
• Observation of quantum jumps in a superconducting artificial atom
• High-Fidelity Readout in Circuit Quantum Electrodynamics Using the Jaynes-Cummings Nonlinearity
• Noiseless nonreciprocity in a parametric active device
• Tunable coupling in circuit quantum electrodynamics with a superconducting V-system
• Improved Superconducting Qubit Readout by Qubit-Induced Nonlinearities
• Response of the Strongly-Driven Jaynes-Cummings Oscillator
• Protocol for high fidelity readout in the photon blockade regime of circuit QED
• Low-crosstalk bifurcation detectors for coupled flux qubits
• Transition from coherent mesoscopic single particle transport to proximity Josephson-current