Speaker: Chen Wang, University of Massachusetts, Amherst
Abstract: Quantum superpositions of distinct coherent states in a single-mode harmonic oscillator have been known as the (Schrödinger) cat states, drawing analogy between the quasi-classical nature of a coherent state to the state of a macroscopic entity. Creation and control of such cat states have been a hallmark of the modern quantum control era and lay the foundation for an interesting class of oscillator-based quantum information processing scheme. Here we take one step further and present experimental demonstration of entangled cat state of electromagnetic fields in two microwave cavities bridged by a superconducting artificial atom. We present full quantum state tomography of this two-mode cat state over a Hilbert space exceeding 100 dimensions via quantum non-demolition measurements of the joint photon number parity. The ability to manipulate such multi-cavity quantum states paves the way for logical operations between redundantly encoded qubits for fault-tolerant quantum computation and communication.