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We present an implementation study of gate-type quantum computing algorithms for the purpose of semiconductor device simulations. As one of the representative quantum algorithms we consider the use of HHL (Harrow–Hassidim–Lloyd) algorithm to solve the Poisson equation in semiconductor nanowire p–n junction under the Neumann boundary condition that the electric field is zero at the electrode boundaries. Our proposed model of the quantum gate to implement the Neumann boundary condition along with the appropriately designed non-uniform mesh grid has been found to successfully reproduce the solution obtained by conventional method. • An efficient quantum computing model to solve Poisson equation under Neumann boundary condition is proposed. • Non-uniform discretization are introduced so that adjacent eigenvalues of the capacitance matrix are separated as equally as possible. • Proposed scheme is found to reproduce accurate solution by a fewer resister qubits unless the charge profile is highly localized. [ABSTRACT FROM AUTHOR]

Abstract: We investigate numerically the effect of the interface structure on the spin-polarization of the electron transmission through zinc-blend semiconductor double barrier resonant tunneling heterostructures in which the well and barrier have a different composition of both anions and cations. Based on the atomistic tight binding model calculations including the intra-atomic spin–orbit interaction, it is demonstrated that the asymmetric configuration of the two barrier/well interfaces results in the strongly anisotropic spin-splitting of the transmission without use of the external electric field, where the interface asymmetry is interpreted to cause the additional effective spin–orbit coupling analogous to the Rashba spin–orbit coupling mechanism. [ABSTRACT FROM AUTHOR]

Ferromagnetism in III–V diluted magnetic semiconductor (DMS) quantum wells is studied theoretically paying special attention to the occupation of multiple subbands by holes and the effect of static electric field perpendicular to the well plane. Our calculations show that the ferromagnetic transition temperature Tc of DMS quantum-well exhibits step-function-like dependence on the carrier concentration, reflecting the quasi-two-dimensional nature of systems. The Tc can be sensitively controlled by the application of electric field when the hole density is small so as to occupy only a few subbands. [Copyright &y& Elsevier]

Abstract: The formulation and calculation of quantum electron transport in double-gate metal oxide semi-conductor field effect transistors (DGMOSFETs) is presented based on multiband non-equilibrium Green''s function (NEGF) formalism. In the formulation we employ the empirical tight-binding approximation (TBA) with nearest neighbor coupling to obtain a realistic fullband structure. The multiband NEGF is performed self-consistently with the Poisson equation to acquire the effect of space charge density. We compare the non-parabolicity feature of bandstructure with that of parabolic effective mass model. Due to the difference in energy dispersion relation, we have found that the results of multiband simulations are quite different with those based on conventional effective mass model. [Copyright &y& Elsevier]

Abstract: We present a theoretical study of the density of states (DOS) and the heat capacity in a spherical quantum dot formed by a spherical thin barrier. The control of the spherical barrier thickness or the potential barrier height is found to cause the dimensional transition from the three-dimensional (3D) behavior to the quasi-zero dimensional (Q0D) behavior in the DOS and the heat capacity. When the barrier is thick enough the DOS shows the Q0D-like behavior but when the barrier is thin enough to allow electrons to tunnel through it, the temperature dependence of the heat capacity exhibits quite distinct behavior depending on the electron density. [Copyright &y& Elsevier]