March 14, 2018
11:00 AM - 12:00 PM
Speaker: Sydney Schreppler
Title: "Quantum Measurement and entanglement with driven transmons"
Among the most elementary of quantum interactions is that of a single photon encountering a single spin. In circuit quantum electrodynamics, this interaction underlies dispersive qubit measurement, photon-assisted entanglement, and the quantum backaction that accompanies each. Understanding the fundamental limits of these processes will help us to design new quantum-limited detectors, computers, and communication protocols. I will describe a method of arranging energy level structures of superconducting transmon qubits using microwave dressing that, when combined with a stroboscopic dispersive tone, induces a response analogous both to back-action evading measurements in cavity optomechanics and to stimulated Raman transitions in trapped ions. With this stroboscopic scheme, we experimentally demonstrate improved qubit measurement using squeezed vacuum, realize multipartite entanglement via shared photonic modes, and establish periodic interactions that may permit studies of out-of-equilibrium many-body states.