Microwave remote state preparation vs. quantum cryptography

Quantum communication protocols employ nonclassical correlations as a resource for an efficient transfer of quantum states [R. Di Candia et al., EPJ Quantum Technol. 2, 25 (2015)]. As a fundamental protocol, remote state preparation (RSP) aims at the preparation of a known quantum state at a remote location using classical communication and quantum entanglement. In our experiment, we use flux-driven Josephson parametric amplifiers and linear circuit elements to generate propagating two-mode squeezed (TMS) microwave states acting as quantum resource [K. G. Fedorov et al., Phys. Rev. Lett. 117, 020502 (2016); K. G. Fedorov et al., Sci. Rep. 8, 6416 (2018)]. Combined with a classical feedforward, we use these TMS states to remotely prepare single-mode squeezed states. Furthermore, we analyze the consumption of quantum discord in our experiment and interpret our results in the framework of a quantum cryptographic protocol analogous to the Vernam cipher.