VietNam 2013 

IXth Rencontres du Vietnam
Quy-Nhon, August 4-10, 2013


 Nanophysics: from fundamentals to applications

(the return)


Wednesday 7
Dots and wires

› 15:00 - 15:20 (20min)
Single-Electron Charge Qubit in a Circuit QED Architecture
Julien Basset  1, *@  
1 : Department of Physics ETH Zurich  (ETH Zurich)  -  Website
CH-8093, Zurich -  Switzerland
* : Corresponding author

In this project we aim at realizing a hybrid solid-state quantum device, in which a semiconductor double quantum dot, acting as a quantum bit near the charge degeneracy point, strongly couples to the quantized voltage oscillations of a nearby superconducting transmission line resonator [1, 2]. This hybrid structure, making use of mesa edge structured double dot and aluminum coplanar waveguide, has already been investigated and showed promising results [2]. However, an important issue of the previous work is that the interaction between the electrons dwelling in the dot might enhance the energy relaxation (100MHz) and the dephasing rate (1-3 GHz) of the qubit. As a result, decoherence processes are faster than the achieved coupling rate (50MHz) with the resonator. In order to study the influence of the number of electrons residing in the dot on qubit decoherence, we have fabricated a novel architecture in which the number of electrons can be controlled down to the last electron. A systematic analysis comparing, within the same sample, single-electron vs many-electron charge qubit shows that electron-electron interactions play a minor role in lowering the decoherence rate. [1] L.Childress, A.S. Sorensen and M.D. Lukin Phys. Rev. A 69, 042302 (2004) [2] T.Frey et al. Phys. Rev. Lett. 108, 046807 (2012).

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