Entangled Microwaves Split Up

Microwave signals in an entangled state can be generated and then spatially separated on a single chip, enabling quantum communication with microwave technology.

Entangled photons are the tools of choice for testing the foundations of quantum physics and demonstrating the teleportation of quantum states. They are also a resource in quantum information protocols. So far, most work has focused on entangled photons at optical frequencies. But for several decades, researchers have been developing a quantum information technology based on superconducting circuits, which have quantized excitations in the form of microwave photons. These circuits are attractive for generating, processing, and storing quantum information because they can be lithographically patterned on a small chip, allowing a good design to be replicated many times over. Now, in Physical Review Letters, Emmanuel Flurin and colleagues at École Normale Supérieure in Paris report they can generate, and then spatially separate, entangled microwave fields in a superconducting circuit [1], enabling quantum teleportation schemes that utilize microwave technology.