Tuesday, May 21, 2013

1305.4588 (M. B. Kenmoe et al.)

SU(3) Landau - Zener Interferometry    [PDF]

M. B. Kenmoe, M. N. Kiselev, K. Kikoin
We consider a general theory of Landau-Zener transitions in a three-level system. Based on a classification of three level crossings we express the Landau - Zener Hamiltonians in terms of two bases: i) spin S=1 SU(2) operators and ii) SU(3) Gell - Mann matrices. We show that the generic Hamiltonians being non-linear in terms of the SU(2) group generators become linear in the SU(3) basis. If the diabatic states of the SU(3) Landau - Zener Hamiltonian form a triangle, the interference between two paths results in formation of "beats" and "steps" pattern in the time-dependent transition probability. The characteristic time scales describing the "beats" and "steps" depend on a dwell time through the triangle. These scales are related to the geometric size of the interferometer. We formulate the SU(3) Landau - Zener problem in terms of Bloch dynamics of a unit vector and find a solution of eight-dimensional Bloch equations in the limit of a non-adiabatic transition. Possible experiments in triangular and linearly arranged triple quantum dots where Landau - Zener interferometry can be used for finding manifestations of SU(3) symmetry are discussed.
View original: http://arxiv.org/abs/1305.4588

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