Generating coherent state of entangled spins

TL;DR

This paper proposes a method to generate entangled coherent states of many spins via incoherent spin pumping, enabling applications in quantum telecloning, secret sharing, and AKLT state construction with high fidelity.

Contribution

The authors introduce a novel scheme for engineering entangled spin states using incoherent pumping, suitable for realistic atomic systems and scalable to hundreds of spins.

Findings

Steady-state entangled spin states can be achieved with high fidelity.

The scheme is feasible in optical lattice systems with decoherence.

Applications include quantum telecloning and large-scale quantum resource states.

Abstract

A coherent state of many spins contains quantum entanglement which increases with a decrease in the collective spin value. We present a scheme to engineer this class of pure state based on incoherent spin pumping with a few collective raising/lowering operators. In a pumping scenario aimed for maximum entanglement, the steady-state of N pumped spin qubits realizes the ideal resource for the 1 to N/2 quantum telecloning. We show how the scheme can be implemented in a realistic system of atomic spin qubits in optical lattice. Error analysis show that high fidelity state engineering is possible for N ~ O(100) spins in the presence of decoherence. The scheme can also prepare a resource state for the secret sharing protocol and for the construction of large scale Affleck-Kennedy-Lieb-Tasaki (AKLT) state.