project title: Tunnel Junction as a Probe of Noise Statistics
project leader: Prof. E. Sonin
access given (in days): 92
access used (in days): 92
local host: Prof. Pertti Hakonen
home institution: Racah Institute of Physics, Hebrew Institute of Physics, Hebrew University of Jerusalem
country of institution: Israel
starting date (yyyy-mm-dd): 2004-08-01
Experimental and theoretical investigations performed in the Low Temperature Laboratory demonstrated that the Coulomb blockaded Josephson junction can be used as an effective probe of shot noise. Further development of this idea requires a deeper theoretical analysis. The objectives of this analysis are to answer the following questions: 1. Can the normal junction be also an effective noise probe? 2. Can other types of noise different from shot noise also be probed with this method? 3. How sensitive to noise is the Josephson junction in the superconducting regime? 4. Can the Coulomb blockaded junction probe the full counting statistics of electron transport?
In the course of joint experimental and theoretical investigationa a clear physical picture of the effect of shot noise on the Coulomb blockaded Josephson junction was obtained. Theory and experiment are in good agreement, and the results of this joint investigation have been published. The theory is now able to answer to the first two questions listed above: 1. The effect of shote noise on the IV curve of the Coulomb blockaded normal junction was calculated. The result of calculation shows that the normal junction is very sensitive to noise similarly to the Josephson junction. 2. The effect of the monochromatic microwave with phase noise (phase decoherence) on the IV curve of the Coulomb blockade Josephson junction was investigated theoretically. This type of noise is widely known and investigated for laser radiation. It is shown that the response of the junction to the microwave input essentially different for noiseless and noisy input. Some preliminary results have also been obtained concerning the two last problems listed above: 3. Using duality relations the effect of shot noise on the superconducting Josephson junction has been investigated. There are theoretical evidences that in this regime the time necessary for an electron to cross the junction can be measured experimentally. However, since the physical nature and the scale of this time remains to be controversial, further analys of the issue is needed. 4. It was shown that at high noise current its effect on the IV curve of the Coulomb blockade junction is strongly different for Poissonian statistics and for a periodic sequence of current pulses. This demonstates sensitivity to the full counting statistics of the electron transport.