VietNam 2013 

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

 QNplage

 Nanophysics: from fundamentals to applications

(the return)

 

Thursday 8
Quantum electronics, quantum information, electronic quantum optics, high frequency noise

› 16:30 - 16:50 (20min)
Dynamical control of tunneling processes to minimize the shot noise in a tunnel junction
Julien Gabelli  1, *@  , Bertrand Reulet  2@  
1 : Laboratoire de Physique des Solides
Univ. Paris-Sud, CNRS, UMR 8502
Bat. 510, Université Paris Sud, F-91405 Orsay Cedex, France -  France
2 : Université de Sherbrooke
Sherbrooke, Québec J1K 2R1, Canada -  Canada
* : Corresponding author

The shot noise of a tunnel junction biased at voltage V and excited by a monochromatic microwave at frequency f exhibits features at eV=nhf with n integer. This reflects the influence of photo-assisted processes in the statistics of electron transport: electrons can cross the barrier by emitting or absorbing photons of energy hf. We report measurements of shot noise in a tunnel junction under biharmonic illumination at frequencies f and 2f. The experiment is performed in the quantum regime, hf >> kBT at low temperature T = 70 mK and high frequency f = 10 GHz. From the measurement of noise at low frequency, we show that we can infer and control the nonequilibrium electronic distribution function by adjusting the amplitudes and phase of the excitation, thus modeling its shape. In particular, we observe that the noise depends not only on the amplitude of the two sine waves but also on their relative phase, due to coherent emission/absorption of photons at different frequencies. We show that adding an excitation at frequency 2f with the proper amplitude and phase can reduce the noise of the junction excited at frequency f only. This behavior is generic for driven quantum systems and is a part of the more general effect of Ramsey multiple-time-slit interferences.


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