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

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

the quantum repeater system comprises two doped polycrystalline ceramic optical devices and repeater entanglement optics;

each doped polycrystalline ceramic optical device 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 optical device 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 optical device and configured such that a plurality of storage photons traversing the doped polycrystalline ceramic optical device attenuate at an attenuation rate of about 3 dB/mm or less;

at least one of the one or more pump lasers are optically coupled to each doped polycrystalline ceramic optical device of the quantum repeater system; and

the repeater entanglement optics comprise two entangling pathways optically coupled to each doped polycrystalline ceramic optical device and a beamsplitter positioned such that each entangling pathway traverses the beamsplitter.

2. The optical system of claim 1 , wherein each doped polycrystalline ceramic optical device is configured such that a plurality of storage photons traversing the doped polycrystalline ceramic optical device attenuate at an attenuation rate of about 2 dB/mm or less.

3. The optical system of claim 1 , wherein each doped polycrystalline ceramic optical device is configured such that a plurality of storage photons traversing the doped polycrystalline ceramic optical device attenuate at an attenuation rate of about 1 dB/mm or less.

4. The optical system of claim 1 , wherein the rare-earth element dopant doped into the doped polycrystalline ceramic optical device is configured to absorb about 50% or more of a plurality of storage photons traversing the doped polycrystalline ceramic optical device.

5. The optical system of claim 1 , wherein the rare-earth element dopant doped into the doped polycrystalline ceramic optical device is configured to store a storage photon for a photon storage lifetime comprising between about 500 ns and about 1 ms.

6. The optical system of claim 1 , further comprising a storage photon generator optically coupled to the doped polycrystalline ceramic optical device.

7. The optical system of claim 6 , wherein the storage photon generator is structurally configured to output an entangled pair of storage photons comprising a first entangled storage photon entangled with a second entangled storage photon.

8. The of claim 1 , wherein the rare-earth element dopant comprises erbium, thulium, praseodymium, or a combination thereof.

9. The optical system of claim 1 , wherein the rare-earth element dopant comprises a non-Kramer's rare-earth ion.

10. The optical system of claim 1 , wherein the rare-earth element dopant comprises between about 0.05% to about 0.15% of a total molecular weight of the doped polycrystalline ceramic optical device.

11. The optical system of claim 1 , wherein the doped polycrystalline ceramic optical device is formed by sintering a plurality of rare-earth doped nanoparticles comprising a diameter of about 40 nm or less.

12. The optical of claim 11 , wherein the plurality of rare-earth doped nanoparticles is formed by mixing a plurality of transition metal complexes and plurality of rare-earth metal complexes to form a metal salt solution, heating the metal salt solution to form a heated metal salt solution, and mixing the heated metal salt solution and an organic precursor.

13. The optical system of claim 1 , wherein the doped polycrystalline ceramic optical device is voidless.

14. The optical system of claim 1 , wherein the doped polycrystalline ceramic optical device comprises yttrium oxide, zirconium oxide, or combinations thereof.

15. The optical system of claim 14 , wherein the doped polycrystalline ceramic optical device is voidless.

16. The optical system of claim 1 , wherein at least 50% of the rare-earth element dopant is doped into grains of the crystal lattice at locations apart from the grain boundaries of the crystal lattice.

17. The optical system of claim 1 , wherein at least 75% of the rare-earth element dopant is doped into grains of the crystal lattice at locations apart from the grain boundaries of the crystal lattice.

18. The optical system system of claim 1 , wherein the polycrystalline ceramic optical device comprises a phonon energy of between about 100 cm −1 and about 800 cm −1 .

19. The optical system system of claim 1 , wherein the polycrystalline ceramic optical device comprises a phonon energy of between about 200 cm −1 and 700 cm −1 .

20. The optical system system of claim 1 , wherein the inhomogeneous linewidth of the doped polycrystalline ceramic optical device doped with the rare-earth element dopant is between about 1 nm and about 25 nm.

21. The optical system system of claim 20 , wherein the inhomogeneous linewidth of the doped polycrystalline ceramic optical device is between about 5 nm and about 15 nm.

22. The optical system system of claim 1 , wherein the homogeneous linewidth of the doped polycrystalline ceramic optical device doped with the rare-earth element dopant is 7.5 MHz or less.

23. The optical system system of claim 1 , comprising a plurality of rare-earth doped nanoparticles.

24. The optical system system of claim 23 , wherein rare-earth doped nanoparticles comprise between about 0.25% rare-earth element dopant and about 0.97% rare-earth element dopant.