Quantum Computation and Information Seminar 

04/12/2007, 14:00 — 15:00 — Room P6, Mathematics Building
Pascal Degiovanni, ENS Lyon

Quantum detection of electronic flying qubits

We consider the problem of detecting ballistic electrons at the edge of a two-dimensional electron gas in the integer quantum Hall regime. This problem is motivated by recent proposals for developing an electronic version of quantum optics with single electrons propagating in nanostructures. A phenomenological model based on a passive RC circuit capacitively coupled to a gate will be considered. Using a quantum description of this circuit, we determine the signal over noise ratio of the detector as well as the backaction on the incident wavepacket in term of the detector characteristics. Using information theory, we define the appropriate notion of quantum limit for such an "on the fly" detector.