Vacuum-induced multipartite entanglement in superconducting microwave cavity under multiple pump tones*

Quantum correlations are an essential resource in advanced information processing based on quantum phenomena. Remarkably, the vacuum state of a quantum field may act as a key element for the generation of strong quantum correlations. Besides, superconducting microwave cavities offer an excellent platform for experimental studies of such quantum effects. In this work, we experimentally investigate vacuum correlations in a flux-tunable superconducting cavity under multiple pump tones. We consider double and triple pumping cases and explore multipartite entanglement between frequency bands. Utilizing the developed scheme that provides us comprehensive control of the entanglement structure, we demonstrate genuine tripartite entanglement of the states. We envision quantum resources facilitated by the multiple pump configuration offers enhanced prospects for quantum data processing using parametric microwave cavities.