Quantum computation

Spin systems have recently been suggested as candidates for the realization of quantum computation and communication protocols

The spin systems considered so far include Spin Gap AFM chains, the two-chain spin ladder. S. Bose Quantum communication through spin chain dynamics: an introductory overview, Contemporary Physics, 48:1, 13-30 (2007).

Entanglement: at the heart of quantum communication and computation

• Two particles are said to be entangled when the quantum state of each particle cannot be described independently, no matter how far apart in space and time the two particles are.
• Photons immediately spring to mind when we talk about long-distance entanglement.
• But the spins at the ends of one-dimensional magnetic chains can be entangled over large distances too
• Any large-scale future quantum computer would likely be a hybrid system consisting of optical and solid-state components — optical components for long-range communication and solid- state components for connecting several quantum processors or gates on small scales.
• Networks or chains of spins could serve as solid-state-based channels for quantum information transfer

Experimental realization of long-distance entanglement between spins in antiferromagnetic quantum spin chains was made in 2015. Sahling et al. demonstrated long-range entanglement in Sr₁₄Cu₂₄O₄₁ consisting of alternating spin-ladder and spin-chain layers. Entanglement can be probed by measurements of macroscopic properties such as magnetic susceptibility.