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Dr. Daniel Esteve

Quantronics group - CEA-Saclay, France

Friday, May 25th, 2012 at 11:00:00 AM  

Conference room Querzoli - LENS - via Nello Carrara 1 - Sesto Fiorentino (Florence)

Enrico Fermi Colloquium

Published on-line at 10:28:10 AM on Saturday, February 18th, 2012

Quantum physics with electrical circuits

Superconducting artificial atoms as quantum bit circuits for processing quantum information.

Solid state electrical circuits that behave as artificial quantum atoms are now fabricated for processing quantum information, and for addressing fundamental issues in quantum mechanics. I will describe how a simple superconducting artificial atom, the Cooper pair box, embedded in a microwave cavity as atoms are in cavity QED experiments, can be used in this aim.

The Cooper pair box, first operated in 1999, is presently the most popular quantum bit circuit. In a single qubit circuit measured and driven at the same time, we have demonstrated the violation of the Leggett and Garg inequality, which falsifies the assumptions of macrorealism considered as plausible for macroscopic systems such as electrical circuits [A. Palacios-Laloy et al., Nature Phys. 6, 442-447 (2010)]. With a two-qubit processor [A. Dewes et al., Phys. Rev. Lett. 108, 057002 (2012)], we have demonstrated the quantum speed-up expected from quantum computing in the simple case of the Grover search algorithm [A. Dewes et al., arXiv:1110.5170].

[video=720 400]a20120525_esteve[/video]

Klein Colloquium by Romolo Savo: "Optics of Lévy glasses".

[video=720 380]b20120525_savo[/video]