Graphene quantum dots for valley-based quantum computing: A feasibility study

TL;DR

This paper explores the potential of using graphene's valley degree of freedom as qubits for quantum computing, demonstrating feasibility through theoretical analysis of double quantum dot structures with promising relaxation and manipulation times.

Contribution

It extends the quantum dot approach to valley qubits in graphene, showing their potential for fast manipulation and long relaxation times, a novel concept in quantum computing.

Findings

Valley relaxation time ~ O(ms)

Electric qubit manipulation time ~ ns

Feasibility of valley qubits in graphene

Abstract

At the center of quantum computing1 realization is the physical implementation of qubits - two-state quantum information units. The rise of graphene2 has opened a new door to the implementation. Because graphene electrons simulate two-dimensional relativistic particles with two degenerate and independent energy valleys,3 a novel degree of freedom (d.o.f.), namely, the valley state of an electron, emerges as a new information carrier.4 Here, we expand the Loss-DiVincenzo quantum dot (QD) approach in electron spin qubits,5,6 and investigate the feasibility of double QD (DQD) structures in gapful graphene as "valley qubits", with the logic 0 / 1 states represented by the "valley" singlet / triplet pair. This generalization is characterized by 1) valley relaxation time ~ O(ms), and 2) electric qubit manipulation on the time scale ~ ns, based on the 1st-order "relativistic effect" unique in graphene. A potential for valley-based quantum computing is present.