Non-universal transmission phase behaviour of a large quantum dot

摘要

The electron wave function experiences a phase modification at coherenttransmission through a quantum dot. This transmission phase undergoes acharacteristic shift of $\pi$ when scanning through a Coulomb-blockaderesonance. Between successive resonances either a transmission phase lapse of$\pi$ or a phase plateau is theoretically expected to occur depending on theparity of the corresponding quantum dot states. Despite considerableexperimental effort, this transmission phase behaviour has remained elusive fora large quantum dot. Here we report on transmission phase measurements acrosssuch a large quantum dot hosting hundreds of electrons. Using an originalelectron two-path interferometer to scan the transmission phase along fourteensuccessive resonances, we observe both phase lapses and plateaus. Additionally,we demonstrate that quantum dot deformation alters the sequence of transmissionphase lapses and plateaus via parity modifications of the involved quantum dotstates. Our findings set a milestone towards a comprehensive understanding ofthe transmission phase of quantum dots.