„Entangled states with spin-orbit coupling: spin measurement and spin driving” – seminarium

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Zapraszamy na Środowiskowe Seminarium Fizyki Ciała Stałego, które odbędzie się w środę 10 grudnia br. o godz. 9:00 w sali 1.02A Akademickiego Centrum Materiałów i Nanotechnologii AGH (ul. Kawiory 30, budynek D-16).

 

Prof. Eugene Ya. Sherman (University of Basque Country UPV-EHU and IKERBASQUE Basque Foundation for Science, Bilbao, Spain) wygłosi referat pt. „Entangled states with spin-orbit coupling: spin measurement and spin driving”.

 

Spin-orbit coupling (SOC) leads to a spin-coordinate entanglement producing mixed states in reduced spin subspace.  We study two consequences of this entanglement for free and driven spin dynamics.
First, SOC simulates a von Neumann measurement of a spin ½ since spatial separation of spin-up and spin-down states decoheres the spin density matrix and allows one reading the spin with the particle coordinate. For a simultaneous measurement of spin projections at orthogonal axes, which cannot be accurately done due to the uncertainty ratio, we find that such a procedure yields measurement-time averages of these projections, which can be precisely known [1]. Second, we consider driving of electron spin by a periodic electric field in a double quantum dot. The interdot tunnelling favours a spin-coordinate entanglement and makes the driving much less efficient than expected. This is, essentially, the Zeno effect of the measurement induced by the spin-orbit coupling, that is slowing of the dynamics of a systems under a permanent observation [2,3]. In addition, this Zeno effect decreases the efficiency of the spin driving with the increase in the spin-orbit coupling strength as found theoretically in [4].

[1] D. Sokolovski and E. Ya. Sherman, Phys. Rev. A 84, 030101(R) (2011)
[2] E. Ya. Sherman and D. Sokolovski , New J. Phys. 16 015013 (2014)
[3] D. V. Khomitsky, L. V. Gulyaev, and E. Ya. Sherman, Phys. Rev. B 85, 125312 (2012)
[4] R. Li, J. Q. You, C. P. Sun, and F. Nori,  Phys. Rev. Lett. 111, 086805 (2013)

 

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