We derive a lower bound for the Wehrl entropy of a single quantum spin. The high-spin asymptotics of this bound coincides with Lieb’s conjecture up to first order in the inverse spin quantum number. The result presented here may be seen as complementary to the verification of the conjecture in cases of lowest spin by Schupp [Commun. Math. Phys. 207 (1999), 481]. In addition, we extend the valid...

in this paper we studied the thermal negativity in a two-qubit xx spin ½ chain model and xxx spin1/2 chain model(isotropic heisenberg model)spin-1/2 chain subjected to an external magnetic field inz direction. we calculate analytical relation for the thermal negativity for two qubit xx and xxx spinchain models in the external magnetic field. effects of the magnetic field and temperature on then...

a new derivation of the quantum boltzmann transport equation for the fermion system from the quantum time evolution equation for the wigner distribution function is presented. the method exhibits the origin of the time - irreversibility of the boltzmann equation. in the present work, the spin dependent and indistinguishibility of particles are also considered.

the effect of impurities on quantum chemical parameters of single-walled nanotubes (swnts) was studied using density functional theory (dft). the density of states (dos), fermi energy and thermodynamic energies of (5,5) carbon nanotubes were calculated in the presence of nitrogen impurity. it was found that this nanotube remains metallic after being doped with one nitrogen atom. the partial den...

stability of the ;-; stacking interactions in the substituted-coronene||cyclooctatetraene complexes wasstudied using the computational quantum chemistry methods (where || denotes ;–; stackinginteraction, and substituted-coronene is coronene which substituted with four similar x groups; x =oh, sh, h, f, cn, and no). there are meaningful correlations between changes of geometricalparameters and t...

We propose a method for quantum computation which uses control of spin-orbit coupling in a linear array of single electron quantum dots. Quantum gates are carried out by pulsing the exchange interaction between neighboring electron spins, including the anisotropic corrections due to spin-orbit coupling. Control over these corrections, even if limited, is sufficient for universal quantum computa...

A Langevin equation for the quantum Brownian motion of a spin of arbitrary size in a uniform external dc magnetic field is derived from the phase space master equation in the weak coupling and narrowing limits, for the quasiprobability distribution (Wigner) function of spin orientations in the configuration space of polar and azimuthal angles following methods long familiar in quantum optics. T...