Alexander Rimberg, Dartmouth College

Topic: "Macroscopic Oscillations Caused by Microscopic Objects"  (Video)

Abstract: What determines the boundary between classical and quantum behavior? Improved control over individual quantum systems, and its relevance to the field of quantum information science, has made this question the focus of intense worldwide interest for the past several years. In our recent work, we have probed the quantum/classical divide by strongly coupling a driven microscopic electrical device to a macroscopic resonator and observing the effects of their interaction on the resulting dynamics. We have done so using two very different physical systems. In one, a quantum point contact embedded in a semiconductor crystal, we find that the shot noise of electrons tunneling through the point contact causes macroscopic mechanical oscillations of the host crystal. In the other, we use the ac Josephson effect of a superconducting artificial atom to cause macroscopic electrical oscillations in a superconducting microwave cavity, in effect producing a single Cooper pair laser. In both cases we find that the behavior of these strongly coupled systems differs significantly from that of their constituent components in isolation.