Talk given by

Prof. Menno Poot
Quantum Technology Group
TU München

München, Germany

Abstract:

Integrated optics provides unprecedented flexibility, scaling possibilities, and stability of optical circuits. In this talk, I will address two topics in this rapidly developing field. By combining movable structures with electrostatic actuation, we developed an opto-electromechanical platform that can be employed as a broadband integrated phase shifter. In vacuum, quality factors up to 300 000 are observed in these devices, which provides an excellent test ground for optomechanical experiments directed towards the quantum regime.. Their motion can be resolved with femtometer resolution, and parametric squeezing is used to reduce the thermal motion. However, when increasing the pump strength, instabilities occur that limit the amount of squeezing that can be realized. By parametrically pumping in the presence of a real-time stabilization of the unstable quadrature, 15 dB of thermo-mechanical noise squeezing is demonstrated. The prospects of using this technique for quantum squeezing are discussed.

In the second part, I will discuss our efforts towards fully-integrated linear-optics quantum circuits. We show the design, fabrication, and characterization of the essential elements, including directional couplers, photonic CNOT gates, phase detection, and superconducting single photon detectors. All of these are monolithically embedded on the same chip. Optomechanical devices also play an important role in this research, as they will enable programmable initialization and tomography of photonic qubits at cryogenic temperatures.