Quantum computing with spin cluster qubits

TL;DR

This paper demonstrates that finite spin chains can host robust spin cluster qubits that are insensitive to internal variations, enabling efficient quantum gate operations without the need for individual spin control.

Contribution

It introduces the concept of spin cluster qubits in finite spin chains, showing their robustness and suitability for quantum computing.

Findings

Spin cluster qubits are defined in odd-site chains' ground state doublet.

These qubits are insensitive to placement and anisotropy.

Quantum gates can be implemented with magnetic fields and exchange interactions.

Abstract

We study the low energy states of finite spin chains with isotropic (Heisenberg) and anisotropic (XY and Ising-like) exchange interaction with uniform and non-uniform coupling constants. We show that for an odd number of sites a spin cluster qubit can be defined in terms of the ground state doublet. This qubit is remarkably insensitive to the placement and coupling anisotropy of spins within the cluster. One- and two-qubit quantum gates can be generated by magnetic fields and inter-cluster exchange, and leakage during quantum gate operation is small. Spin cluster qubits inherit the long decoherence times and short gate operation times of single spins. Control of single spins is hence not necessary for the realization of universal quantum gates.