Abstract: Electron spins in semiconductor quantum dots typically interact with many nuclear spins in their semiconductor environments, realizing a manifestation of the central spin problem. The central spin problem is a widely studied model of decoherence and is predicted to exhibit a rich variety of interesting and useful phenomena, only some of which have been observed. In this talk, I will discuss a series of experiments exploring these dynamics in silicon quantum dots. We report evidence for the formation of a nuclear dark state, which occurs when the nuclei are driven into a state that does not interact with the electrons. We show evidence that this dark state depends on the synchronized precession of the nuclear spins, and that driving the nuclear spins into the dark state promotes increased lifetimes of electronic spin states. We also discuss the relationship between the dark state and the coherence time of electronic spin states.
Bio: John Nichol is an associate professor in the Department of Physics and Astronomy at the University of Rochester. He earned a PhD from the University of Illinois at Urbana-Champaign and a BA from St. Olaf College. Nichol investigates the quantum mechanics of nanoscale objects, especially individual electrons in semiconductor quantum dots. Nichol's current research focuses on improving the coherence of electron spin qubits using new materials and control methods, exploring new ways to transfer quantum information between distant spin qubits, and many-body quantum coherence in spin chains. Nichol is the recipient of an NSF CAREER award, a Google Research Scholar Award, and a Moore Foundation Experimental Physics Investigator Award.
*You will need to bring your cell phone, so you can sign in using the QR code outside of ATL 2400. You will need to submit your first and last name, email, and affiliation on a form by 11:15am to be able to get lunch after the seminar. Lunch is first come, first served.*