Principal Investigator Simon Gustavsson
One of the cornerstone concepts of quantum mechanics is the superposition principle as demonstrated in the double-slit experiment. The partial waves of individual particles passing a double slit interfere with each other. The average of many particles detected on a screen agrees with the interference pattern calculated using propagating waves. This has been demonstrated for photons, electrons in vacuum as well as for more massive objects like C60-molecules. The Aharonov-Bohm (AB) geometry provides an analogous experiment in solid-state systems. Partial waves passing the arms of a ring acquire a phase difference due to a magnetic flux, enclosed by the two paths.
In this experiment, we use the time-resolved charge detection techniques to count electrons one-by-one as they pass through our ring-like interferometer. Electrons are provided from the source contact, tunnel into QD1 and pass on to QD2 through either or both of the two arms. Upon arriving in QD2, the electrons are detected in real-time by monitoring the conductance of the nearby QPC. Depending on the magnetic flux threading the ring, we expect the electron wavefunctions to interfere constructively or destructively. The number of electrons arriving in QD2 should therefore form an interference pattern as a function of magnetic field.