Strong light-matter coupling to protect quantum information with Schrodinger cat states

The Kerr-cat qubit is a bosonic qubit in which the information is encoded in multi-photon cat states. The suppressed bit flip rate makes this qubit a promising candidate for implementing quantum error correction codes tailored for noise-biased qubits. Moreover, its intrinsic nonlinearities enable fast logic gates and QND measurement. However, the strong drive required for stabilization tends to heat the qubit and degrade its performance. We demonstrate a 2D implementation of this qubit by increasing the light-matter coupling without compromising the single photon lifetime due to Purcell decay. This was enabled by an on-chip band-block filter that prevents the qubit from decaying while allowing the microwave drives used for stabilization and readout to pass through. We also demonstrate a new X(90) gate based on phase modulating the stabilization drive to realize universal control. Leveraging the new schemes for stabilization and control, we demonstrate a bit-flip time exceeding 1 ms, readout QNDness of 99.6%, and universal gates with fidelities higher than 90%. Finally, we present our progress in increasing the Kerr nonlinearity from 1.2 MHz to 14 MHz.