The quantum-spin $S=1/2$ chain system ${\mathrm{Cs}}_{2}\mathrm{Cu}{\mathrm{Cl}}_{4}$ is of high interest due to competing antiferromagnetic intrachain $J$ and interchain exchange ${J}^{\ensuremath{'}}$ interactions represents a paramount example for Bose-Einstein condensation magnons [R. Coldea et al., Phys. Rev. Lett. 88, 137203 (2002)]. Substitution chlorine by bromine allows tuning the corr...

Although silicon is a promising material for quantum computation, the degeneracy of the conduction band minima (valleys) must be lifted with a splitting sufficient to ensure the formation of well-defined and long-lived spin qubits. Here we demonstrate that valley separation can be accurately tuned via electrostatic gate control in a metal-oxide-semiconductor quantum dot, providing splittings sp...

We investigate nonequilibrium transport in the absence of spin-flip energy relaxation in a few-electron quantum dot artificial atom. Novel nonequilibrium tunneling processes involving high-spin states, which cannot be excited from the ground state because of spin blockade, and other processes involving more than two charge states are observed. These processes cannot be explained by orthodox Cou...

Hot carrier-induced spin dynamics is analyzed in epitaxial Au/Fe/MgO(001) by a time domain approach. We excite a spin current pulse in Fe by 35 fs laser pulses. The transient spin polarization, which is probed at the Au surface by optical second harmonic generation, changes its sign after a few hundred femtoseconds. This is explained by a competition of ballistic and diffusive propagation consi...

Nonexponential relaxation is found in extremely diverse physical systems such as structural glasses, spin glasses, polymers and random systems in general, all of which can be classified as complex [1]. More recently, pinned density-wave (DW) systems with either charge or spin modulation have been added to this list [2]. Although a wide variety of mechanisms can produce nonexponential relaxation...

Bose-Einstein condensates have been prepared in long-lived metastable excited states. Two complementary types of metastable states were observed. The first is due to the immiscibility of multiple components in the condensate, and the second to local suppression of spin-relaxation collisions. Relaxation via recondensation of noncondensed atoms, spin relaxation, and quantum tunneling was observed...

We use the Hanle effect to study spin relaxation in ZnxCd1−xSe epilayers grown on latticematched InP substrates. We study three samples with a fixed composition (x = 0.4) and with varying levels of n-doping, as well as an undoped sample with x = 0.5. Our measurements show that the spin relaxation time changes non-monotonically as a function of carrier density, with a maximum transverse spin lif...

Magnetic Resonance Imaging (MRI) techniques have been used to determine the spin-lattice, T1, and the spin-spin, T2, relaxation times in three phantoms with compositions simulating the T1 and T2 values of human tissues. Some methods of analysis were used in order to obtain the relaxation time maps. It has been shown that reliable results can be also obtained by using approximating methods of in...