Entangled microwave photons form a fundamental resource for quantum information processing and sensing with continuous variables. We use a low-loss Josephson metamaterial comprising superconducting, non-linear, asymmetric inductive elements to generate frequency-entangled photons from vacuum fluctuations at a rate of 2 giga entangled bits per second spanning over 4 GHz bandwidth. The device is operated as a traveling wave parametric amplifier under Kerr-relieving biasing conditions. Furthermore, we realize the first successfully demonstration of single-mode squeezing in such devices -- 3.1±0.7\,dB below the zero-point level at half of modulation frequency.
@article{arxiv.2111.06145,
title = {Broadband continuous variable entanglement generation using Kerr-free Josephson metamaterial},
author = {Michael Perelshtein and Kirill Petrovnin and Visa Vesterinen and Sina Hamedani Raja and Ilari Lilja and Marco Will and Alexander Savin and Slawomir Simbierowicz and Robab Jabdaraghi and Janne Lehtinen and Leif Grönberg and Juha Hassel and Mika Prunnila and Joonas Govenius and Sorin Paraoanu and Pertti Hakonen},
journal= {arXiv preprint arXiv:2111.06145},
year = {2022}
}