We introduce the nonlinear spin-coherent state (SCS) via its ladder operator formalism and propose a type of nonlinear SCS by the nonlinear time evolution of the SCS. By a new version of spectroscopic squeezing criteria we study the spin squeezing in both the SCS and the nonlinear SCS. The results show that the SCS is not squeezed in the x, y and z directions, and the nonlinear SCS may be squee...

A novel implementation of a charge based quantum computer is proposed. There is no charge transfer during calculation, therefore, uncontrollable entan-glement between qubits due to long-range Coulomb forces is suppressed. High-speed computation with 1ps per an operation looks as feasible. Almost all recent experimental realizations of quantum computation accomplished on several qubits and even ...

The main source of decoherence for an electron spin confined to a quantum dot is the hyperfine interaction with nuclear spins. To analyze this process theoretically we diagonalize the central spin Hamiltonian in the high magnetic B-field limit. Then we project the eigenstates onto an unpolarized state of the nuclear bath and find that the resulting density of states has Gaussian tails. The leve...

A novel implementation of a charge based quantum computer is proposed. There is no charge transfer during calculation, therefore, uncontrollable entan-glement between qubits due to long-range Coulomb forces is suppressed. High-speed computation with 1ps per an operation looks as feasible. Almost all recent experimental realizations of quantum computation accomplished on several qubits and even ...

We developed a spin transport model for a diffusive channel with coupled localized states that result in an effective increase of spin precession frequencies and a reduction of spin relaxation times in the system. We apply this model to Hanle spin precession measurements obtained on monolayer epitaxial graphene on SiC(0001). Combined with newly performed measurements on quasi-free-standing mono...

The combination of spin transitions and magnetic ordering provides an interesting structure of phase transitions in Prussian blue analogues (PBAs). To understand the structure of stable and metastable states of Co-Fe PBA, it is necessary to clarify free energy as a function of magnetization and the fraction of the high-temperature component. Including the magnetic interaction between high-tempe...

It is shown that several different order parameters can be used to characterize a type of P and T -violating state for spin systems, that we call chiral spin states. There is a closely related, precise notion of chiral spin liquid states. We construct soluble models, based on P and T symmetric local spin Hamiltonians, with chiral spin ground states. Mean field theories leading to chiral spin li...

Spin-dependent intramolecular electron transfer is revealed in the ReI(CO)3(py)(bpy-Ph)-perylenediimide radical anion (ReI-bpy-PDI-•) dyad, a prototype model system for artificial photosynthesis. Quantum chemical calculations and ultrafast transient absorption spectroscopy experiments demonstrate that selective photoexcitation of ReI-bpy results in electron transfer from PDI-• to ReI-bpy, formi...

We report on spin injection experiments at a Co/Al2O3/GaAs interface with electrical detection. The application of a transverse magnetic field induces a large voltage drop DeltaV at the interface as high as 1.2 mV for a current density of 0.34 nA.microm(-2). This represents a dramatic increase of the spin accumulation signal, well above the theoretical predictions for spin injection through a f...

Mineral properties in Earth's lower mantle are affected by iron electronic states, but representative pressures and temperatures have not yet been probed. Spin states of iron in lower-mantle ferropericlase have been measured up to 95 gigapascals and 2000 kelvin with x-ray emission in a laser-heated diamond cell. A gradual spin transition of iron occurs over a pressure-temperature range extendin...