Dephasing in a quantum dot due to coupling with a quantum point contact.pdf

arXiv:cond-mat/9702164v1 [cond--hall] 18 Feb 1997 EUROPHYSICS LETTERS Europhys. Lett., (), pp. () Dephasing in a quantum dot due to coupling with a quan- tum point contact Yehoshua Levinson Weizmann Institute of Science, 76100 Rehovot, Israel (received ; accepted in ?nal form ) PACS. .-b – Mesoscopic systems. PACS. .-d – Theory of electronic transport; scattering mechanisms. Abstract.– We consider the dephasing of an one-electron state in a quantum dot due to charge ?uctuations in a biased quantum point contact coupled to the dot capacitively. The contribution to the dephasing rate due to the bias depends ontemperature and bias in the same way as shot-noise in the point contact at zero frequency, butdo not follow the|t| 2(1?|t| 2) suppression. Recently, it became possible to measure the phase and hence also the coherence of resonance electron transmission through a (pinched) quantum dot (QD)[1, 2, 3, 4]. Experiments of this type are performed using Aharonov-Bohm rings loaded by a QD in one of its arms, the ring being imbedded in a two- or four-terminal con?guration. Theconductance of such a system contains a term oscillating with ic ?ux Φ threaded trough the ring and this term is sensitive to the phase of the transmission amplitudet QDthrough the QD. If the transmission through the QD is coherent one can calculateGfrom the Landauer formula in terms of the t