Experimental Realization and Characterization of Stabilized Pair Coherent State II : State Characterization Results

The stabilization of Bosonic qubits in microwave cavities is a promising step towards implementing quantum error correction codes. The pair cat code, which utilizes a two mode entangled state, assures significant advantages over the previously implemented one-mode cat code for autonomous quantum error correction schemes. A pair coherent state (PCS) forms the basis of this pair cat code. This work is the first implementation of an engineered non-linear two-photon driven dissipation across two storage cavities that generates and stabilizes PCS.

This is part II of the talk and I will be presenting the experimental results along with the simualtion we did to extract the two photon pumping and dissipation rates. The reduced model Hamiltonian after adiabatically eliminating the reservoir mode is used to numerically solve the master equation and fits the time domain measurement data to a great agreement. I will also present the experimental results of coherence characterization we did with the new tool called subspace tomography and discuss the error channel. The non-negligible cross-Kerr between the dissipative mode and the storage cavities proved to be the limiting factor for the coherence we see in the stabilized PCS. Going forward if we are can eliminate the cross-Kerr our experimental parameters promise a PCS with better fidelity as we confirm with the simulation.