Intrinsic bidirectional dynamic nuclear polarization by optically pumped trions in quantum dots

This paper has been updated by the author to: arXiv:1012.0060v1 [cond-mat.mes-hall], titled "Collective Nuclear Stabilization by Optically Excited Hole in Quantum Dot

A Quantum Approach of Meso-Magnet Dynamics with Spin Transfer Torque

We present a theory of magnetization dynamics driven by spin-polarized current in terms of the quantum master equation. In the spin coherent state representation, the master equation becomes a Fokker-Planck equation, which naturally includes the spin transfer and quantum fluctuation. The current electron scattering state is correlated to the magnet quantum states, giving rise to quantum correction to the electron transport properties in the usual semiclassical theory. In the large spin limit, the magnetization dynamics is shown to obey the Hamilton-Jacobi equation or the Hamiltonian canonical equations.Comment: 7 pages, expanded version with 2 figures and appendix par

Coherent exciton transport in semiconductors

We review the topic of Bose-Einstein condensation of excitons in semiconductors, focusing on the signatures of the macroscopic order of the exciton condensate.Comment: Some references were updated with respect to the published version. appears as Chapter 19 in Novel Superfluids Volume 2, edited by K. H. Bennemann and J. B. Ketterson, International Series of Monographs on Physics no. 157, pages 423-474 (Oxford University Press, Oxford, 2014

Quark and Leptonic Mixing Patterns from the Breakdown of a Common Discrete Flavor Symmetry

Assuming the Majorana nature of neutrinos, we recently performed a scan of leptonic mixing patterns derived from finite discrete groups of order less than 1536. Here we show that the 3 groups identified there as giving predictions close to experiment, also contain another class of abelian subgroups that predict an interesting leading order quark mixing pattern where only the Cabibbo angle is generated at leading order. We further broaden our study by assuming that neutrinos are Dirac particles and find 4 groups of order up to 200 that can predict acceptable quark and leptonic mixing angles. Since large flavor groups allow for a multitude of leading order mixing patterns, we define a measure that is suitable to compare the predictivity of a given flavor group taking this fact into account. We give the result of this measure for a wide range of discrete flavor groups and identify the group (Z_18 \times Z_6) \rtimes S_3 as being most predictive in the sense of this measure. We further discuss alternative measures and their implications.Comment: 11 pages, 4 figure

Quantum measurement of hyperfine interaction in nitrogen-vacancy center

We propose an efficient quantum measurement protocol for the hyperfine interaction between the electron spin and the $^{15}$N nuclear spin of a diamond nitrogen-vacancy center. In this protocol, a sequence of quantum operations of successively increasing duration is utilized to estimate the hyperfine interaction with successively higher precision approaching the quantum metrology limit. This protocol does not need the preparation of the nuclear spin state. In the presence of realistic operation errors and electron spin decoherence, the overall precision of our protocol still surpasses the standard quantum limit