Hardware efficient quantum computing using repetition cat qubits.

Quantum error correcting codes provide, when operated below the threshold, an arbitrary good protection against noise, thus solving the decoherence problem for quantum information processing. However, their actual implementation usually comes at the price of a tremendous physical resource overhead. Our approach to reduce the physical cost of quantum computing is the use of cat-qubits in a simple repetition code. The cat-qubits, stabilized by a two-photon driven dissipative process, exhibit a tunable noise bias where the effective bit-flips are exponentially suppressed with the average number of photons. Exploiting this noise bias, a universal set of fully protected logical gates can be implemented on the repetition code, achieving very low logical error rates with a reasonable physical overhead. In this talk, I will present the key points of the approach and give estimates of the expected performance based on numerical simulations of the circuits including realistic error models for all the gates and operations.