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TT: Tiefe Temperaturen

TT 20: Niederdimesnionale Systeme, Magnetotransport, Quantenhalleffekt II

TT 20.10: Talk

Thursday, March 29, 2001, 11:45–12:00, A

Shot Noise by Quantum Scattering in Chaotic Cavities — •Stefan Oberholzer¹, Eugene Sukhorukov¹, Christoph Strunk², and Christian Schönenberger¹ — ¹Institute of Physics, University of Basel, CH-4056 Basel, Switzerland — ²Institute of Experimental and Applied Physics, University of Regensburg, D-93040 Regensburg, Germany

We will discuss new experimental results about shot noise of chaotic cavities defined by two quantum point contacts in a high mobility heterostructure. If the contacts are open (no partial backscattering) no noise is generated by the contacts themselves and shot noise arises inside the cavity due to quantum mechanical diffraction. In our experiment, the cavity noise could be determined for the first time as 1/4· 2e|I| in agreement with the theoretical prediction. For partially closed contacts the measured noise is larger because of additional partitioning at the contacts. Subsequently, we have found that cavity noise decreases if one of the contacts is further opened and reaches nearly zero for a highly asymmetric cavity.

In addition, we started to investigate the classical-to-quantum crossover of the shot noise in chaotic cavities. Since in the classical limit, there is no diffraction inside the cavity shot noise should be absent, too. Experimentally, the classical chaotic regime can be achieved varying the size of the cavity, the opening of the contacts and by applying a weak magnetic field. Our previous results show that shot noise can be strongly suppressed below 1/4· 2e|I| even if the cavity is still fully chaotic.