Quantum-Coherent Transportin Quantum Hall Devices

V. J. Goldman, Stony Brook University, DMR-0303705

We have fabricated Aharonov-Bohm electroninterferometers, operating in very high magnetic fields and ultra-low temperatures.An atomic force microscope (AFM) image of a typical device is shown. The electrons are constrained to move in a 2D plane, 300 nmbelow the semiconductor surface. Four goldgates are used to control tunneling and thesymmetry of the device.

Experiments show characteristic quantum interference patterns for both electrons and fractionally-charged Laughlin quasiparticles.For the first time ever, we observe Aharonov-Bohm “superperiod”, a period more than the h/e fundamental flux quantum. The results are interpreted as a direct demonstration of a fractional statistics of Laughlin quasiparticles.

Physical Review B 72, 075342 (2005)

Education:Two graduate (Wei Zhou, Jie Yu), one undergraduate (Jia G. Li, female) and one postdoc (Dr. Fernando E. Camino) worked on research supported by this NSF Award.

The lab web site http://quantum.physics.sunysb.edu/ contains pictures and description of equipment and facilities, and recent research presentations. It is also used in education as the web site of classes taught by Prof. Goldman. It averages 2000 hits per month from all over the world.

Societal Impact:The ability to transport electrons and fractional quasiparticles quantum-coherently is a very powerful technique. It promises to lead to the development of new kinds of electronic devices, including quantum computers. First experimental demonstration of fractional statistics is of a fundamental importance for basic science.

Quantum-Coherent Transportin Quantum Hall Devices

V. J. Goldman, Stony Brook University, DMR-0303705