Photon-assisted electron transport through a quantum point contact in a microwave field

It has been shown by the numerical solution of the time-dependent Schrödinger equation that the transmittance of an electron through a smooth one-dimensional barrier in a microwave field can increase by orders of magnitude in the tunneling regime and decrease strongly in the open regime. The leading contribution comes from transitions with absorption or emission of a few photons. The discovered effect can explain a recently observed strong increase in the conductance of a quantum point contact under microwave irradiation.