Generating Entangled Microwave Radiation Over Two Transmission Lines

Abstract

Using a superconducting circuit, the Josephson mixer, we demonstrate the first experimental realization of spatially separated two-mode squeezed states of microwave light. Driven by a pump tone, a first Josephson mixer generates, out of quantum vacuum, a pair of entangled fields at different frequencies on separate transmission lines. A second mixer, driven by a $\pi$-phase shifted copy of the first pump tone, recombines and disentangles the two fields. The resulting output noise level is measured to be lower than for vacuum state at the input of the second mixer, an unambiguous proof of entanglement. Moreover, the output noise level provides a direct, quantitative measure of entanglement, leading here to the demonstration of 6 Mebit.s${}^{-1}$ (Mega entangled bits per second) generated by the first mixer.

5 pages, 4 figures. Supplementary Information can be found here as an ancillary file

References in corpus (6)

• Amplification and squeezing of quantum noise with a tunable Josephson metamaterial
• Observation of -9 dB quadrature squeezing with improvement of phase stability in homodyne measurement
• Gaussian measures of entanglement versus negativities: the ordering of two-mode Gaussian states
• Widely tunable, non-degenerate three-wave mixing microwave device operating near the quantum limit
• Entanglement of formation for an arbitrary two-mode Gaussian state
• Experimental characterization of Gaussian quantum communication channels

Cited by in corpus (5)

• Path Entanglement of Continuous-Variable Quantum Microwaves
• Non-degenerate, three-wave mixing with the Josephson ring modulator
• Tunable coupling engineering between superconducting resonators: from sidebands to effective gauge fields
• Relativistic Quantum Teleportation with Superconducting Circuits
• Observation of Entanglement Between Itinerant Microwave Photons and a Superconducting Qubit