Multi-mode and long-lived quantum correlations between photons and spins in a crystal

Abstract

The realization of quantum networks and quantum repeaters remains an outstanding challenge in quantum communication. These rely on entanglement of remote matter systems, which in turn requires creation of quantum correlations between a single photon and a matter system. A practical way to establish such correlations is via spontaneous Raman scattering in atomic ensembles, known as the DLCZ scheme. However, time multiplexing is inherently difficult using this method, which leads to low communication rates even in theory. Moreover, it is desirable to find solid-state ensembles where such matter-photon correlations could be generated. Here we demonstrate quantum correlations between a single photon and a spin excitation in up to 12 temporal modes, in a ${}^{151}$Eu${}^{3+}$ doped Y${}_2$SiO${}_5$ crystal, using a novel DLCZ approach that is inherently multimode. After a storage time of 1 ms, the spin excitation is converted into a second photon. The quantum correlation of the generated photon pair is verified by violating a Cauchy - Schwarz inequality. Our results show that solid-state rare-earth crystals could be used to generate remote multi-mode entanglement, an important resource for future quantum networks.

References in corpus (6)

• The Quantum Internet
• Quantum Storage of Photonic Entanglement in a Crystal
• Quantum storage of entangled telecom-wavelength photons in an erbium-doped optical fibre
• Coherent spin control at the quantum level in an ensemble-based optical memory
• Cavity-enhanced storage in an optical spin-wave memory
• A photon-pair source with controllable delay based on shaped inhomogeneous broadening of rare-earth doped solids

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• Optical and spin manipulation of non-Kramers rare-earth ions under weak magnetic field for quantum memory applications
• Dissipative phonon Fock state production in strong nonlinear optomechanics
• Precision measurements of electric-field-induced frequency displacements of an ultranarrow optical transition in ions in a solid
• Nonclassical photon-pair source based on noiseless photon echo