Environmental Modeling of Silicon Dangling Bond QCA Wires

TL;DR

This paper models environmental interactions in silicon dangling bond QCA wires, revealing challenges in long wire reliability due to phonon interactions and proposing quantum annealing to improve state stability.

Contribution

It introduces a detailed environmental model for silicon dangling bond QCA wires and suggests quantum annealing as a method to mitigate long wire errors.

Findings

Short wires operate reliably at liquid nitrogen temperatures.

Long wires experience exponential polarization decay due to thermal equilibrium.

Quantum annealing can help bring wires into their ground state before operation.

Abstract

Interactions of quantum cellular automata (QCA) circuits with their environment induce transitions in their quantum states that can cause errors in computation. The nature of these interactions depend on the specific physical implementation of the circuit. In the case of silicon dangling bond QCA, one channel of environmental interaction is between dangling bond cells and longitudinal phonons in the silicon lattice. In the presence of this environmental interaction, short 4 cell wire simulations show reliable operation at liquid nitrogen temperature, however simulation and theoretical arguments suggest long wires operated from thermal equilibrium are susceptible to exponential decay of cell polarization along their length regardless of clock zoning. Quantum annealing is suggested as a technique for bringing QCA wires into their ground state prior to information transmission to circumvent this problem.