The Kerr-cat qubit: towards enhanced error suppression using dissipation

Biased-noise qubits are a promising approach for realizing hardware-efficient quantum processors. By sufficiently suppressing the bit-flip error rate, the complexity of error correction schemes can be relaxed to a repetition code in the limit of infinite noise bias. One prominent candidate for this architecture is the Kerr-cat qubit, implemented by squeezing a Kerr-nonlinear oscillator. The Kerr-cat qubit admits superpositions of the oscillator's coherent states, i.e., cat states, as degenerate ground states. Under the cat-state encoding, the rate of bit-flip errors decreases exponentially with the amplitude of the coherent states. However, recent work has shown that leakage outside the computational manifold limits the suppression of bit-flip errors below the exponential limit [1]. Theoretical work has shown that such leakage can be mended by introducing carefully designed dissipative interactions [2, 3]. Here we show progress toward incorporating engineered dissipation mechanisms to enhance the qubit's bit flip time.

[1] N. E Frattini et al., arXiv:2209.03934 (2022).

[2] H. Putterman et al., Phys. Rev. Lett. 128, 110502 (2022).

[3] J. Venkatraman et al., arXiv:2209.11193 (2022).