| 1. |
- Suri, Baladitya, 1984, et al.
(författare)
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Nonlinear microwave photon occupancy of a driven resonator strongly coupled to a transmon qubit
- 2015
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Ingår i: Physical Review A - Atomic, Molecular, and Optical Physics. - 2469-9926 .- 2469-9934. ; 92:6
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Tidskriftsartikel (refereegranskat)abstract
- We measure photon occupancy in a thin-film superconducting lumped element resonator coupled to a transmon qubit at 20mK and find a nonlinear dependence on the applied microwave power. The transmon-resonator system was operated in the strong dispersive regime, where the ac Stark shift (2χ) due to a single microwave photon present in the resonator was larger than the linewidth (Γ) of the qubit transition. When the resonator was coherently driven at 5.474 325 GHz, the transition spectrum of the transmon at 4.982 GHz revealed well-resolved peaks, each corresponding to an individual photon number-state of the resonator. From the relative peak heights we obtain the occupancy of the photon states and the average photon occupancy n¯ of the resonator. We observe a nonlinear variation of n¯ with the applied drive power Prf for n¯
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| 2. |
- Bishop, Lev S., et al.
(författare)
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Proposal for generating and detecting multi-qubit GHZ states in circuit QED
- 2009
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Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 11, s. 073040-
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Tidskriftsartikel (refereegranskat)abstract
- We propose methods for the preparation and entanglement detectionof multi-qubit Greenberger–Horne–Zeilinger (GHZ) states in circuit quantumelectrodynamics. Using quantum trajectory simulations appropriate for thesituation of a weak continuous measurement, we show that the joint dispersivereadout of several qubits can be utilized for the probabilistic production ofhigh-fidelity GHZ states. When employing a nonlinear filter on the recordedhomodyne signal, the selected states are found to exhibit values of theBell–Mermin operator exceeding 2 under realistic conditions. We discuss thepotential of the dispersive readout to demonstrate a violation of the Merminbound, and present a measurement scheme avoiding the necessity for fulldetector tomography.
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| 3. |
- Chow, J.M., et al.
(författare)
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Randomized benchmarking and process tomography for gate errors in a solid-state qubit
- 2009
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Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 102:9
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Tidskriftsartikel (refereegranskat)abstract
- We present measurements of single-qubit gate errors for a superconducting qubit. Results from quantum process tomography and randomized benchmarking are compared with gate errors obtained from a double pulse experiment. Randomized benchmarking reveals a minimum average gate error of 1.1±0.3% and a simple exponential dependence of fidelity on the number of gates. It shows that the limits on gate fidelity are primarily imposed by qubit decoherence, in agreement with theory.
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