Path entanglement constitutes an essential resource in quantum information and communication protocols. Here, we demonstrate frequency-degenerate entanglement between continuous-variable quantum microwaves propagating along two spatially separated paths. We combine a squeezed and a vacuum state using a microwave beam splitter. Via correlation measurements, we detect and quantify the path entanglement contained in the beam splitter output state. Our experiments open the avenue to quantum teleportation, quantum communication, or quantum radar with continuous variables at microwave frequencies.
@article{arxiv.1210.4413,
title = {Path Entanglement of Continuous-Variable Quantum Microwaves},
author = {E. P. Menzel and R. Di Candia and F. Deppe and P. Eder and L. Zhong and M. Ihmig and M. Haeberlein and A. Baust and E. Hoffmann and D. Ballester and K. Inomata and T. Yamamoto and Y. Nakamura and E. Solano and A. Marx and R. Gross},
journal= {arXiv preprint arXiv:1210.4413},
year = {2012}
}