464 research outputs found
Fast geometric gate operation of superconducting charge qubits in circuit QED
A scheme for coupling superconducting charge qubits via a one-dimensional
superconducting transmission line resonator is proposed. The qubits are working
at their optimal points, where they are immune to the charge noise and possess
long decoherence time. Analysis on the dynamical time evolution of the
interaction is presented, which is shown to be insensitive to the initial state
of the resonator field. This scheme enables fast gate operation and is readily
scalable to multiqubit scenario
Charting the circuit QED design landscape using optimal control theory
With recent improvements in coherence times, superconducting transmon qubits
have become a promising platform for quantum computing. They can be flexibly
engineered over a wide range of parameters, but also require us to identify an
efficient operating regime. Using state-of-the-art quantum optimal control
techniques, we exhaustively explore the landscape for creation and removal of
entanglement over a wide range of design parameters. We identify an optimal
operating region outside of the usually considered strongly dispersive regime,
where multiple sources of entanglement interfere simultaneously, which we name
the quasi-dispersive straddling qutrits (QuaDiSQ) regime. At a chosen point in
this region, a universal gate set is realized by applying microwave fields for
gate durations of 50 ns, with errors approaching the limit of intrinsic
transmon coherence. Our systematic quantum optimal control approach is easily
adapted to explore the parameter landscape of other quantum technology
platforms.Comment: 13 pages, 5 figures, 2 pages supplementary, 1 supplementary figur
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