Quantum spin chains and Majorana states in arrays of coupled qubits

TL;DR

This paper explores how coupled qubit arrays can simulate quantum spin chains and host Majorana fermion states, with potential applications in decoherence-protected quantum computing.

Contribution

It proposes a qubit model of the 1D quantum Ising spin chain with variable interactions and demonstrates the realization of Majorana states in this system.

Findings

Majorana states are localized at chain ends.

Qubit interactions can be tuned via Josephson and capacitive coupling.

Potential for decoherence-protected quantum computing.

Abstract

Several designs of inter-qubit coupling are considered. It is shown that by a combination of Josephson and capacitive coupling one can realize qubit interactions of variable spin content. Qubit arrays are discussed as models of quantum spin chains. In particular, a qubit model of the 1D quantum Ising spin chain is proposed. A realization of unpaired Majorana fermion states in this system is considered. It is shown that Majorana states are represented by spin flip excitations localized on the chain ends. Using unpaired Majorana states in qubit chains for decoherence protected quantum computing is discussed.