$π$-junction qubit in monolayer graphene

Colin Benjamin, Jiannis K. Pachos

Published 2008-08-14, updated 2009-03-25Version 3

We propose to combine the advantages of graphene, such as easy tunability and long coherence times, with Josephson physics to manufacture qubits. If these qubits are built around a 0 and $\pi$ junction they can be controlled by an external flux. Alternatively, a d-wave Josephson junction can itself be tuned via a gate voltage to create superpositions between macroscopically degenerate states. We show that ferromagnets are not required for realizing $\pi$ junction in graphene, thus considerably simplifying its physical implementation. We demonstrate how one qubit gates, such as arbitrary phase rotations and the exchange gate, can be implemented.