Double dot chain as a macroscopic quantum bit

TL;DR

This paper models a quantum dot array as a macroscopic quantum bit, demonstrating its robustness against decoherence at zero temperature and exploring potential quantum information applications.

Contribution

It introduces a new effective two-level system model for a quantum dot array, showing exponential energy gap reduction and robustness to decoherence in the macroscopic limit.

Findings

Effective two-level system with exponentially small energy gap

Robustness against zero-temperature decoherence

Potential applications in quantum information processing

Abstract

We consider an array of N quantum dot pairs interacting via Coulomb interaction between adjacent dots and hopping inside each pair. We show that at the first order in the ratio of hopping and interaction amplitudes, the array maps in an effective two level system with energy separation becoming exponentially small in the macroscopic (large N) limit. Decoherence at zero temperature is studied in the limit of weak coupling with phonons. In this case the macroscopic limit is robust with respect to decoherence. Some possible applications in quantum information processing are discussed.