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arXiv · 1302.4122

Protected gates for superconducting qubits

Peter Brooks·Alexei Kitaev·John Preskill
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Abstract

We analyze the accuracy of quantum phase gates acting on "0-$π$ qubits" in superconducting circuits, where the gates are protected against thermal and Hamiltonian noise by continuous-variable quantum error-correcting codes. The gates are executed by turning on and off a tunable Josephson coupling between an $LC$ oscillator and a qubit or pair of quits; assuming perfect qubits, we show that the gate errors are exponentially small when the oscillator's impedance $\sqrt{L/C}$ is large compared to $\hbar/4e^2 \approx 1\, kΩ$. The protected gates are not computationally universal by themselves, but a scheme for universal fault-tolerant quantum computation can be constructed by combining them with unprotected noisy operations. We validate our analytic arguments with numerical simulations.

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Peter Brooks, Alexei Kitaev, John Preskill. 2013-02-17. Protected gates for superconducting qubits. https://doi.org/10.1103/physreva.87.052306

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