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Entangled quantum particles, in which operating on one particle instantaneously influences the state of the entangled particle, are attractive options for carrying quantum information at the nanoscale. However, fully-describing entanglement in traditional time-dependent quantum transport simulation approaches requires significant computational effort, bordering on being prohibitive. Considering electrons, one approach to analyzing their entanglement is through modeling the Coulomb interaction via the Wigner formalism. In this work, we reduce the computational complexity of the time evolution of two interacting electrons by resorting to reasonable approximations. In particular, we replace the Wigner potential of the electron–electron interaction by a local electrostatic field, which is introduced through the spectral decomposition of the potential. It is demonstrated that for some particular configurations of an electron–electron system, the introduced approximations are feasible. Purity, identified as the maximal coherence for a quantum state, is also analyzed and its corresponding analysis demonstrates that the entanglement due to the Coulomb interaction is well accounted for by the introduced local approximation. [ABSTRACT FROM AUTHOR]

Monte Carlo simulations coupled self-consistently with the three-dimensional Poisson equation are carried out under the double-gate MOSFET structures. The Coulomb force experienced by an electron inside the device is directly evaluated by performing the Monte Carlo simulations with or without the full Coulomb interaction and the Coulomb force on the channel electron corresponding to plasmon excitations is clarified. It is pointed out that the consistency of the boundary condition is achieved only if the long-range Coulomb interaction is properly taken into account, and this is crucial for predicting reliable device characteristics in ultra-small devices. The drain current and transconductance are greatly reduced if the self-consistent potential fluctuations are taken into account. [ABSTRACT FROM AUTHOR]

In our attempts to scale FETs to the 10 nm length, alternatives to conventional Si CMOS are sought on the grounds that: (1) Si seems to have reached its technological and performance limits and (2) the use of alternative high-mobility channel materials will provide the missing performance. With the help of numerical simulations here we establish the reasons why indeed Si seems to have hit an intrinsic performance barrier and whether or not high mobility semiconductors can indeed grant us our wishes. The role of long-and short-range electron-electron interactions are revisited together with a recent analysis of the historical performance trends. The density-of-states (DOS) bottleneck and source starvation issues are also reviewed to see what advantage alternative substrates may bring us. Finally, the well-known ‘virtual source model’ is analyzed to assess whether it can be used as a quantitative tool to guide us to the 10 nm gate length. [ABSTRACT FROM AUTHOR]

Finding the scalar potential from the Poisson equation is a common, yet challenging problem in semiconductor modeling. One of the central problems in traditional mesh-based methods is the assignment of charge to the regular mesh imposed for the discretisation. In order to avoid this problem, we create a mesh-free algorithm which starts by assigning each mesh point to each particle present in the problem. This algorithm is based on a Fourier series expansion coupled with point matching. We show that this approach is accurate and capable of solving the Poisson equation on any point distribution. [ABSTRACT FROM AUTHOR]

Aim of this work is the analytical solution of the time-independent Schrödinger equation for the system of two electrons running along two parallel quantum wires. The solution has been obtained by means of a series expansion using the Frobenius method. A final analysis of the results has been carried out and the two-particle electron densities for several values of the distance between the wires and of the system energy are reported. [ABSTRACT FROM AUTHOR]