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Events on Thursday, August 18th, 2011

R. G. Herb Condensed Matter Seminar
Spins in GaAs: 2 dots - 2 qubits
Time: 10:00 am
Place: 5310 Chamberlin
Speaker: Dr. Lars Schreiber, Kavli Institute of Nanoscience, TU Delft, The Netherlands
Abstract: Electron spins in electrostatically defined quantum dots are promising for defining qubits. As suggested in the proposal by Loss and DiVincenzo, we define one qubit per electron spin. Applying microwaves (10 GHz) to one of the top gates, we observe photon-assisted tunneling (PAT) across a GaAs double dot. PAT is considered to be a spin conserving process. Surprisingly, we observe magnetic field dependent (PAT) resonances indicating a change of the two-electron spin state during tunneling. Changing the external magnetic field and the double-dot detuning, we spectroscopically image the energy of the two-electron spin states.

In addition, for the first time, we performed single-shot read-out of two (solid-state) spins in a double dot. Detection is done by energy-dependent tunneling of the two electrons to the adjacent electron reservoirs. This method allows us to measure the (anti-)correlations of a spin singlet state and to characterize the swap gate fidelity.
Host: Mark Eriksson
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