You are all invited to come to the QN Seminar (and the department coffee half-hour starting 14.30 at the QT coffee bar)
Date: Wednesday 18 December, 2013
Time: 15.00 hours
Place: LECTURE ROOM E, Lorentzweg 1, Delft
Host: Lieven Vandersypen
Speaker: M.A. Eriksson, University of Wisconsin-Madison
Title: Coherent Oscillations in a Si/SiGe Quantum Dot Hybrid Qubit
I will discuss measurement and manipulation of the recently proposed quantum dot hybrid qubit, in these experiments formed in a Si/SiGe double quantum dot. X-rotations on the Bloch sphere are performed by pulsing a gate voltage so that the detuning of a double quantum dot makes the (1,2) and (2,1) occupation ground states degenerate [2]. The resulting rotations occur at approximately 5 GHz and reveal an experimentally measured visibility greater than 80%. Z-rotations on the Bloch sphere are performed by pulsing a gate voltage away from the (1,2)-(2,1) degeneracy point, resulting in oscillations at a rate of approximately 10 GHz and a measured visibility greater than 85%. The T2* time at this detuning is greater than 15 ns, many times longer than the 100 ps gate operation time. Methods for future improvements of the oscillation visibility will be discussed. This work was supported in part by ARO (W911NF-12-0607), NSF (DMR-1206915), and the United States Department of Defense. The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the official policies, either expressly or implied, of the US Government.
[1] Z. Shi, et al., Phys. Rev. Lett. 108, 140503 (2012).
[2] Teck Seng Koh, et al., Phys. Rev. Lett. 109, 250503 (2012).