X-Ray-Generated Heralded Macroscopical Quantum Entanglement of Two Nuclear Ensembles
Wen-Te Liao1,2*, Christoph H. Keitel1, Adriana Pálffy1
1Max-Planck-Institut für Kernphysik, Heidelberg, Germany
2Physics, National Central University, Taoyuan, Taiwan
* presenting author:WEN-TE LIAO, email:wente.liao@g.ncu.edu.tw
Heralded entanglement between macroscopical samples is an important resource for present quantum technology protocols, allowing quantum communication over large distances. In such protocols, optical photons are typically used as information and entanglement carriers between macroscopic quantum memories placed in remote locations. Here we investigate theoretically a new implementation which employs more robust x-ray quanta to generate heralded entanglement between two iron borate crystal-hosted macroscopical nuclear ensembles. Mössbauer 57Fe nuclei in the two iron borate crystals interact collectively with an x-ray spontaneous parametric down conversion photon that generates heralded macroscopical entanglement with coherence times of approximately 100 ns at room temperature. The quantum phase between the entangled crystals can be conveniently manipulated by magnetic field rotations at the 57FeBO3 crystals. The inherent long nuclear coherence times allow also for mechanical manipulations of the samples, for instance to check the stability of entanglement in the x-ray setup. Our results pave the way for first quantum communication protocols that use x-ray qubits.

W.-T. Liao, C. H. Keitel and A. Pálffy, Sci. Rep. 6, 33361 (2016).

Keywords: Iron Borate crystal, Mössbauer effect, Quantum entanglement, Hard x-ray, Magnetic control