Dissipative Stabilization of Squeezing Beyond 3 dB in a Microwave Mode
Rémy Dassonneville, Réouven Assouly, Théau Peronnin, Aashish A. Clerk, Audrey Bienfait, Benjamin Huard · PRX Quantum · 2021
While a propagating state of light can be generated with arbitrary squeezing by pumping a parametric resonator, the intraresonator state is limited to 3 dB of squeezing.Here, we implement a reservoir-engineering method to surpass this limit using superconducting circuits.Two-tone pumping of a three-wave-mixing element implements an effective coupling to a squeezed bath, which stabilizes a squeezed state inside the resonator.Using an ancillary superconducting qubit as a probe allows us to perform a direct Wigner tomography of the intraresonator state.The raw measurement provides a lower bound on the squeezing at about 6.7 ± 0.2 dB below the zero-point level.Further, we show how to correct for resonator evolution during the Wigner tomography and obtain a squeezing as high as 8.2 ± 0.8 dB.Moreover, this level of squeezing is achieved with a purity of 0.91 ± 0.09.