Valley pair qubits in double quantum dots of gapped graphene

TL;DR

This paper provides a comprehensive theoretical analysis of valley pair qubits in double quantum dots of gapped graphene, highlighting a unique relativistic effect enabling fast, all-electric qubit manipulation with long coherence times.

Contribution

It introduces a detailed theory of valley pair qubits in gapped graphene, emphasizing a novel relativistic mechanism for qubit control and analyzing fault tolerance and coherence.

Findings

Fast all-electric qubit manipulation in nanoseconds

Long qubit coherence time (~1 ms) at 10 K

Identification of a unique relativistic effect in gapped graphene

Abstract

The rise of graphene opens a new door to qubit implementation, as discussed in the recent proposal of valley pair qubits in double quantum dots of gapped graphene (Wu et al., arXiv: 1104.0443 [cond-mat.mes-hall]). The work here presents the comprehensive theory underlying the proposal. It discusses the interaction of electrons with external magnetic and electric fields in such structures. Specifically, it examines a strong, unique mechanism, i.e., the analogue of the 1st-order relativistic effect in gapped graphene. This mechanism is state mixing free and allows, together with the electrically tunable exchange coupling, a fast, all-electric manipulation of qubits via electric gates, in the time scale of ns. The work also looks into the issue of fault tolerance in a typical case, yielding at 10oK a long qubit coherence time (~O(ms)).