The Physics & Astronomy Colloquium Series presents Jason Petta of UCLA Department of Physics and HRL Laboratories, Inc., discussing "Spin Qubits: From a Sketch on a Napkin to Experimental Reality" on Oct. 21.

Abstract: Over twenty years ago, Daniel Loss and David DiVincenzo proposed using the spin of a single electron as a quantum bit [1]. At the time of the proposal, it was not possible to trap a single electron in a semiconductor device and measure its spin, let alone demonstrate control of spin coherence. In this colloquium, I will give a broad overview of spin qubits, highlighting some of the first demonstrations of single spin initialization, control, coupling, and measurement in III/V semiconductors [2]. A recent emphasis on spin qubits in isotopically enriched silicon, which supports much longer spin coherence times, has resulted in dramatic experimental progress. I will describe recent experiments where we achieve single spin initialization and readout with errors <1%, single qubit control with a fidelity exceeding 99.95%, and a two-qubit gate with a fidelity of 99.8% [3,4]. These results pave the way for more advanced implementations using industrially fabricated silicon spin qubits