Events in Physics
Quantum coherent phenomena of single and few particle emitters
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.
[See also the Physics Day]