Entangling microwaves and optics

Entanglement enables quantum advantage over classical applications. Entanglement between similar systems such as photons, ions, atoms and nuclear spins has already shown this advantage in information processing, communication, cryptography and sensing.

Moreover, hybrid entanglement between localized systems and itinerant photons has extended these applications to distributed quantum computing and sensing. Thus far, such hybrid entanglement has remained divided into two paradigms - microwave photons entangled with microwave-based quantum devices such as  superconducting qubits, and optical photons entangled with optically-addressable systems such as atoms. Uniting these two paradigms will enable new capabilities in hybrid quantum networks, sensing and meteorology. The required entanglement between itinerant microwave and optical light is challenging to demonstrate due to the incompatibility of low loss superconductivity and  high energy optical photons which prevent the required ultra-low noise conditions. In this talk, I will present a deterministic preparation of an entangled microwave-optical state in the continuous variable domain that is squeezed 0.7 dB below the vacuum level achieved in a triply resonant, pulsed electro-optic interconnect working in a millikelvin environment.