Resonant Fibonacci Quantum Well Structures

We propose a resonant one-dimensional quasicrystal, namely, a multiple quantum well (MQW) structure satisfying the Fibonacci-chain rule with the golden ratio between the long and short inter-well distances. The resonant Bragg condition is generalized from the periodic to Fibonacci MQWs. A dispersion equation for exciton-polaritons is derived in the two-wave approximation, the effective allowed and forbidden bands are found. The reflection spectra from the proposed structures are calculated as a function of the well number and detuning from the Bragg condition.Comment: 5 pages, 3 figures, submitted to Phys. Rev.

Dramatic impact of pumping mechanism on photon entanglement in microcavity

A theory of entangled photons emission from quantum dot in microcavity under continuous and pulsed incoherent pumping is presented. It is shown that the time-resolved two-photon correlations drastically depend on the pumping mechanism: the continuous pumping quenches the polarization entanglement and strongly suppresses photon correlation times. Analytical theory of the effect is presented.Comment: 6 pages, 3 figure

Wood anomalies in resonant photonic quasicrystals

A theory of light diffraction from planar quasicrystalline lattice with resonant scatterers is presented. Rich structure, absent in the periodic case, is found in specular reflection spectra, and interpreted as a specific kind of Wood anomalies, characteristic for quasicrystals. The theory is applied to semiconductor quantum dots arranged in Penrose tiling.Comment: 6 pages, 3 figure

Deduction of Pure Spin Current from Spin Linear and Circular Photogalvanic Effect in Semiconductor Quantum Wells

We study the spin photogalvanic effect in two-dimensional electron system with structure inversion asymmetry by means of the solution of semiconductor optical Bloch equations. It is shown that a linearly polarized light may inject a pure spin current in spin-splitting conduction bands due to Rashba spin-orbit coupling, while a circularly polarized light may inject spin-dependent photocurrent. We establish an explicit relation between the photocurrent by oblique incidence of a circularly polarized light and the pure spin current by normal incidence of a linearly polarized light such that we can deduce the amplitude of spin current from the measured spin photocurrent experimentally. This method may provide a source of spin current to study spin transport in semiconductors quantitatively

Non-Markovian spin relaxation in two-dimensional electron gas

We analyze by Monte-Carlo simulations and analytically spin dynamics of two-dimensional electron gas (2DEG) interacting with short-range scatterers in nonquantizing magnetic fields. It is shown that the spin dynamics is non-Markovian with the exponential spin relaxation followed by the oscillating tail due to the electrons residing on the closed trajectories. The tail relaxes on a long time scale due to an additional smooth random potential and inelastic processes. The developed analytical theory and Monte-Carlo simulations are in the quantitative agreement with each other.Comment: 6 pages, 3 figure

Magneto-Gyrotropic Photogalvanic Effects in Semiconductor Quantum Wells

We show that free-carrier (Drude) absorption of both polarized and unpolarized terahertz radiation in quantum well (QW) structures causes an electric photocurrent in the presence of an in-plane magnetic field. Experimental and theoretical analysis evidences that the observed photocurrents are spin-dependent and related to the gyrotropy of the QWs. Microscopic models for the photogalvanic effects in QWs based on asymmetry of photoexcitation and relaxation processes are proposed. In most of the investigated structures the observed magneto-induced photocurrents are caused by spin-dependent relaxation of non-equilibrium carriers