arXiv subjects

Alexander V. Khaetskii

Publications and source records attributed to Alexander V. Khaetskii.

4 recordsLinked to original sources

arXiv2002

Spin decay and quantum parallelism

We study the time evolution of a single spin coupled inhomogeneously to a spin environment. Such a system is realized by a single electron spin bound in a semiconductor nanostructure and interacting with surrounding nuclear spins. We find striking dependencies on the type of the initial state of the nuclear spin system. Simple product states show a profoundly different behavior than randomly correlated states whose time evolution provides an illustrative example of quantum parallelism and entanglement in a decoherence phenomenon.

cond-mat.mes-hall↗

arXiv2001

Spin-flip transitions between Zeeman sublevels in semiconductor quantum dots

We have studied spin-flip transitions between Zeeman sublevels in GaAs electron quantum dots. Several different mechanisms which originate from spin-orbit coupling are shown to be responsible for such processes. It is shown that spin-lattice relaxation for the electron localized in a quantum dot is much less effective than for the free electron. The spin-flip rates due to several other mechanisms not related to the spin-orbit interaction are also estimated.

cond-mat.mes-hall↗

arXiv2000

Comment on "Spin relaxation in quantum Hall systems"

W. Apel and Yu.A. Bychkov have recently considered the spin relaxation in a 2D quantum Hall system for the filling factor close to unity [PRL v.82, 3324 (1999)]. The authors considered only one spin flip mechanism (direct spin-phonon coupling) among several possible spin-orbit related ones and came to the conclusion that the spin relaxation time due to this mechanism is quite short: around $10^{-10}$ s at B=10 T (for GaAs). This time is much shorter than the typical time ($10^{-5}$ s) obtained earlier by D. Frenkel while considering the spin relaxation of 2D electrons in a quantizing magnetic field without the Coulomb interaction and for the same spin-phonon coupling. I show that the authors' conclusion about the value of the spin-flip time is wrong and have deduced the correct time which is by several orders of magnitude longer. I also discuss the admixture mechanism of the spin-orbit interaction.

cond-mat.mes-hall↗

arXiv1999

Spin relaxation in semiconductor quantum dots

We have studied the physical processes responsible for the spin -flip in GaAs quantum dots. We have calculated the rates for different mechanisms which are related to spin-orbit coupling and cause a spin-flip during the inelastic relaxation of the electron in the dot both with and without a magnetic field. We have shown that the zero-dimensional character of the problem when electron wave functions are localized in all directions leads to freezing out of the most effective spin-flip mechanisms related to the absence of the inversion centers in the elementary crystal cell and at the heterointerface and, as a result, to unusually low spin-flip rates.

cond-mat.mes-hall↗