糖心TV

Recent experiments have demonstrated several electron sources that can controllably inject single or few particles into an electric circuit. This is a novel field of research that is at the very forefront of current investigations of quantum coherent electron transport in low temperature, on-chip electron transport. Experimentally the domain requires mastery of high-frequency measurements and theoretically it represents a push into largely unexplored dynamic electron transport theory. Different sources which are currently under investigation are emitters based on quantum pumps, mesoscopic capacitors or trains of Lorentzian pulses applied to a sample. Of interest is the full quantum statistics of the emitters which permits to assess their fidelity. The advent of single particle emitters opens unprecedented control in the generation and manipulation of quantum coherent few electron states. The generation of two-particle states has recently been successfully demonstrated. For such coherent multiparticle states the synchronization of single particle emitters becomes important as well as the coherence of the emitted states. The workshop is to present some of the key experimental and theoretical advances in this young field.

Colloquium

Markus Buttiker

University of Geneva

We explain and illustrate the revolution which single and few particle emitters bring to electron physics. The structures are similar to those implemented in small semiconductor chips used in present day computers except that transport is investigated at sub-Kelvin temperatures at which electrons exhibit particle-wave duality. Most electron physics has thus far used electrons injected from metallic contacts. Due to the Pauli principle and the quantum Hall effect the phase space for electrons can be reduced sufficiently to observe two-particle electron states. In particular we predicted an Aharonov-Bohm effect which exists only due to the simultaneous presence of two particles and has recently been observed. To prove that these states are entangled poses a problem. Ideally Bell tests require equal time measurements. This is presently difficult since we can typically not observe individual electrons. Thus we can infer the equal time behavior only from long time measurements. This opens a loop hole. Alternatively we can increase control by generating quantum states with single particle emitters and in this way assure that at given instant only two excess particles participate in transport.