Resonant Generation of Schrödinger Cat States in Circuit QED

Schrödinger cat states, superpositions of opposite phase coherent states in a resonator, are nonclassical states that have recently gained a rejuvenated interest. Typical methods use a qubit-resonator system in the dispersive regime to generate such states. Such methods depend on Kerr nonlinearities and multiphoton driving processes. However, we can do much better by using a resonant qubit-resonator system with an additional resonant classical drive on the qubit. Using this method, we can generate Schrödinger cat states in a fast and resonant manner. In this case, the average photon number of the resonator grows linearly in time. This allows for cat states with lobes that grow in time. Detrimental effects to a circuit QED implementation include resonator-drive cross-talk, detuning, decoherence and excitation leakage to the third state. In this presentation, we outline how to create a cat state using a driven qubit-resonator system, and we discuss methods to deal with detuning, cross-talk, leakage and decoherence.