University of Minnesota
School of Physics & Astronomy

Physics and Astronomy Calendar

Wednesday, February 17th 2016
1:25 pm:
Speaker: John Nichol, Harvard University
Subject: Quantum control and sensing with electron spins in semiconductors

Confined spins in semiconductors are a versatile platform for exploring quantum information processing and condensed matter physics. Individual spins can have coherence times exceeding seconds in some cases, making them promising quantum bits, or qubits, and also highly sensitive probes of their local electric and magnetic environments. I will discuss recent work exploiting the joint spin-state of two electrons in a GaAs double quantum dot as a “singlet-triplet” qubit. We perform high-fidelity single- and two-qubit gates with this architecture. We also use the qubit as a sensor to precisely measure its magnetic environment, which results from the statistically fluctuating nuclear spins in the semiconductor crystal. Using these measurement techniques, we extend the qubit coherence time by more than two orders of magnitude through adaptive control, and we uncover the surprisingly strong effect of spin-orbit coupling on electron-nuclear dynamics in GaAs.

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