Entangled spins

Nature Phys. http://doi.org/zxx (2015)

Two particles are entangled when their quantum state cannot be described independently. Such interdependence can be exploited for computing, communication or cryptography purposes. Photons are commonly used for practical applications mainly because they can be easily manipulated, although solid-state components would be desirable for the development of quantum computers. Now, Sven Sahling et al. demonstrate the entanglement of unpaired spins separated by several hundred ångströms in bulk Sr₁₄Cu₂₄O₄₁. This layered material is formed by dimerized spin chains. The chain lattice structure — formed by two sublattices — causes a modulated potential that gives rise to unpaired spins at well-defined positions within a chain. Below 2.1 K the spins become entangled through antiferromagnetic interactions, which is reflected in the macroscopic properties, such as the magnetization and the specific heat, of the bulk material. The experimental results suggest that the dimers could potentially be used as data buses for the transmission of quantum information over mesoscopic distances.