PHYSICS/BK21 SEMINAR[03.18]

“Non-demolition Spin State Detection with mesoscopic interferometers ”

* Speaker : Dr. Sam Young Cho

(Centre for Modern Physics and Department of Physics, Chongqing University, Chongqing, China )

* Place : Physics Seminar Room (Science Bldg, 3-201)

* Date & Time : Mar, 18 (Thu) 4:00 ~ 5:00 pm

Ø Abstract

Recent advances in nanotechnology have made it possible to transport electron spins coherently

over hundreds of micrometers at low temperature. Controllable spin-orbit interactions in the nanoscale

quantum devices have provided an electrical way of manipulating ballistic electron spins without magnetic

fields and magnets. Such a manipulation of the spin degree of freedom of electrons without destroying

their phase coherence may also allow us a possible way to detect spin state of electron.

In this talk, a theoretical model will be discussed by introducing a mesoscopic scale electronic interferometer

with local spin-orbit interactions. Passing through the loop interferometer, an injected electron can induce

a charge loop current due to the spin-dependent quantum interference via the local spin-orbit interaction

in one of the interferometer arms even for spin-unpolarized injections. The loop current is shown to depend

on the spin state of injected electron as well as its spin polarization. Further, it is found that the transmitted

electron has the same spin state with the injected electron. As a consequence, it is shown that a spin state

of injected electron can be determined from the behavior of loop currents as the Rashba spin-orbit

interaction varies.

Contact Person : Prof. Yoon Hee Jeong (054-279-2078, yhj@postech.ac.kr)