Quantum Lunch: Quantum optics meets superconducting qubits

Speaker: Professor Anders Søndberg Sørensen from NBI

Title: Quantum optics meets superconducting qubits

Abstract:
Disclaimer: I gave this talk as the CMT seminar a few weeks ago. At that time the room was full and not everybody could get in. Therefore I repeat the same talk here.

Superconducting qubits is one of the leading technologies for making quantum information processors. Impressive performance has been achieved with a few qubits, and the challenge is now to scale these advances into large scale quantum networks. I will present a few theories for how ideas from quantum optics may help to achieve this.

First, I will present a theory for how superconducting qubits can potentially be linked to optical photons. The electric field surrounding a superconducting qubit can be strong enough to provide a sizeable coupling to a nearby molecule in an optical waveguide. By sending in single photons through the waveguide, this coupling enables the generation of quantum entanglement between the superconducting qubit and the outgoing photons. This entanglement then enables the superconducting qubits to be connected over long distances in a quantum internet.

Secondly, I will present a theory for how to create a microwave single photon transistor, where a single incident photon, triggers a large stream of photons. Such a device would then allow for the detection of single microwave photons by detection the large amplified signal. These single photons detectors can then facilitate merging small quantum information processor into large scale devices.