Quantum-Dot Cellular Automata using Buried Dopants

TL;DR

This paper explores using buried dopants in silicon to create quantum-dot cellular automata, demonstrating potential for ultra-fast quantum switching and discussing advantages over traditional quantum-dot systems.

Contribution

It introduces a novel buried dopant approach for quantum-dot cellular automata, analyzing switching speeds, decoherence effects, and potential for quantum computing architectures.

Findings

Incoherent switching times are microseconds.

Quantum coherent switching can reach tens of picoseconds.

Decoherence limits operation times.

Abstract

The use of buried dopants to construct quantum-dot cellular automata is investigated as an alternative to conventional electronic devices for information transport and elementary computation. This provides a limit in terms of miniaturisation for this type of system as each potential well is formed by a single dopant atom. As an example, phosphorous donors in silicon are found to have good energy level separation with incoherent switching times of the order of microseconds. However, we also illustrate the possibility of ultra-fast quantum coherent switching via adiabatic evolution. The switching speeds are numerically calculated and found to be 10's of picoseconds or less for a single cell. The effect of decoherence is also simulated in the form of a dephasing process and limits are estimated for operation with finite dephasing. The advantages and limitations of this scheme over the more conventional quantum-dot based scheme are discussed. The use of a buried donor cellular automata system is also discussed as an architecture for testing several aspects of buried donor based quantum computing schemes.