Quantum memory systems and quantum repeater systems comprising doped polycrystalline ceramic optical devices and methods of manufacturing the same

An optical system comprising a quantum repeater system, one or more magnetic field generation units, one or more storage photon generators, and one or more pump lasers, wherein:

• the quantum repeater system comprises two doped polycrystalline ceramics and repeater entanglement optics;
• each doped polycrystalline ceramic of the quantum repeater system is positioned within a magnetic field of the one or more magnetic field generation units when the one or more magnetic field generation units generate the magnetic field;
• each doped polycrystalline ceramic of the quantum repeater system is doped with a rare-earth element dopant that is uniformly distributed within a crystal lattice of the doped polycrystalline ceramic and comprises about 0.01% to about 2% of a total molecular weight of the doped polycrystalline ceramic;
• each doped polycrystalline ceramic is optically coupled to at least one of the one or more the storage photon generators, which are structurally configured to output an entangled pair of storage photons comprising a first entangled storage photon entangled with a second entangled storage photon;
• and
• each doped polycrystalline ceramic is optically coupled to at least one of the one or more pump lasers;
• and
• the repeater entanglement optics comprise two entangling pathways optically coupled to each doped polycrystalline ceramic and a beamsplitter positioned such that each entangling pathway traverses the beamsplitter.

A quantum memory system comprising a doped polycrystalline ceramic, a magnetic field generation unit, a storage photon generator, and one or more pump lasers, wherein:

• the doped polycrystalline ceramic is positioned within a magnetic field of the magnetic field generation unit when the magnetic field generation unit generates the magnetic field;
• the one or more pump lasers are optically coupled to the doped polycrystalline ceramic;
• the storage photon generator is optically coupled to the doped polycrystalline ceramic and is structurally configured to output entangled pairs of storage photons comprising a first entangled storage photon entangled with a second entangled storage photon;
• and
• the doped polycrystalline ceramic is doped with a rare-earth element dopant that is configured to absorb about 70% or more of storage photons that propagate into the doped polycrystalline ceramic and store an absorbed storage photon for a photon storage lifetime of from about 1 μs to about 1 ms and is configured such that a plurality of storage photons traversing the doped polycrystalline ceramic attenuate at an attenuation rate of about 2 dB/mm or less.