An electron within a mesoscopic (quantum-coherent) spintronic structure is described by a single wave function which, in the presence of both charge scattering and spin-orbit coupling, encodes an information about entanglement of its spin and orbital degrees of freedom. The quantum state—an improper mixture—of experimentally detectable spin subsystem is elucidated by evaluating quantum informat...

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...

Quantum Spin-Hall systems are topological insulators displaying dissipationless spin currents flowing at the edges of the samples. In contradistinction to the Quantum Hall systems where the charge conductance of the edge modes is quantized, the spin conductance is not and it remained an open problem to find the observable whose edge current is quantized. In this paper, we define a particular ob...

Significant experimental progresses in recent years have generated continued interest in quantum computation. A practical quantum computer would employ thousands if not millions of coherent qubits, and maintaining coherence in such a large system would be imperative for its utility. As an attempt at understanding the quantum coherence of multiple qubits, here we study decoherence of a multi-spi...

We propose a new efficient scheme for the quantum Monte Carlo study of quantum critical phenomena in quantum spin systems. Rieger and Young’s Trotter-number-dependent finite-size scaling in quantum spin systems and Ito et al.’s evaluation of the transition point with the non-equilibrium relaxation in classical spin systems are combined and generalized. That is, only one Trotter number and one i...

Spin chains are paradigmatic systems for the studies of quantum phases and phase transitions, and for quantum information applications, including quantum computation and short-distance quantum communication. Here we propose and analyse a scheme for conditional state transfer in a Heisenberg XXZ spin chain which realizes a quantum spin transistor. In our scheme, the absence or presence of a cont...

We investigate the ground-state energy and spin of disordered quantum dots using spin-density-functional theory. Fluctuations of addition energies (Coulomb-blockade peak spacings) do not scale with average addition energy but remain proportional to level spacing. With increasing interaction strength, the even-odd alternation of addition energies disappears, and the probability of non-minimal sp...

Quantum orders in symmetric spin liquids. Quantum orders and.These lectures are an introduction to world of quantum fluids and to phenomena. To motivate the study of quantum turbulence one has to appreciate the.In order to understand how nucleation proceeds in quantum liquids such as. Cavitation in liquid helium, but I also consider water, liquid hydrogen, wet.As you can imagine, the number of ...

We consider quantum graphs with spin-orbit couplings at the vertices. Timereversal invariance implies that the bond S-matrix is in the orthogonal or symplectic symmetry class, depending on spin quantum number s being integer or half-integer, respectively. The periodic-orbit expansion of the spectral form factor is shown to acquire additional weights from spin rotations along orbits. We determin...