Fault-tolerant gates for protected superconducting qubits

Brooks, Kitaev and Preskill (BKP) [1] showed that it is in principle possible to perform fault-tolerant gate operations on protected superconducting qubits at the physical level by coupling to an ancillary oscillator. In this talk we describe a general framework for performing fault-tolerant gates on protected qubits using quantum error correcting codes. We illustrate the main ideas using a toy model of a qubit coupled to a CSS code and discuss how the code’s distance relates to the circuit parameters of the oscillator in the BKP proposal. We also present numerical results for the scaling of the intrinsic gate error as a function of these parameters and comment on the feasibility of physical implementations.

[1] Brooks, Phys. Rev. A 87, 052306 (2013)