potential energy. Using multiphoton processes induced by longitudinal coupling fields and frequency matching conditions, we design a universal algorithm to produce arbitrary superpositions of two-mode photon states of microwave fields in two separated transmission line resonators, which are coupled to a superconducting qubit. Based on our algorithm, we analyze the generation of evenly-populated states and NOON states. Compared to other proposals with only single-photon process, we provide an efficient way to produce entangled microwave states when the interactions between superconducting qubits and microwave fields are in the ultrastrong regime.
Engineering entangled microwave photon states via multiphoton transitions between two cavities and a superconducting qubit
It has been shown that there are extbf{}not only transverse but also longitudinal couplings between microwave fields and a superconducting qubit with broken inversion symmetry of the