DEPHASING DUE TO WHICH PATH DETECTOR

We study dephasing of electrons induced by a which path detector and t hus verify Bohr's complementarity principle for fermions. We utilize a double path interferometer with two slits, with one slit being replac ed by a coherent quantum dot (QD). A short one dimensional channel, in the form of a quantum point contact (QPC), in close proximity to the QD, serves as a which path detector. We find that by varying the prope rties of the QPC detector we affect the visibility of the interference , inducing thus dephasing. We develop a simple model to explain the de phasing due to the detector and find good agreement with the experimen t. (C) 1998 Elsevier Science B.V. All rights reserved.