Research projects

	Four-wave mixing Efficent transfer of entanglement in photons to stationary qubits such as atoms requires narrowband photons. We generate narrowband correlated photon pairs via four wave mixing in a Rubidium-87 MOT.
	Single atom quantum interfaces One of the cleanest quantum information storage systems are internal degrees of freedom of single atoms. We want to understand the basics of atom-light interaction for future quantum interfaces.
	Quantum hacking Quantum key distribution can be really secure if you have a clean system and you know everything about it. Realistic systems, however, do have issues, and we look into physical vulnerabilities of representative implementations.
	Sources of entangled photon pairs Most quantum information experimens depend on strong sources for entangled photons. We try to improve the entanglement quality, brightness and usability of such sources based on parametric down conversion.
	Quantum cryptography A practical application of quantum information ideas to establish a secure communication channel. Our experiments implement entanglemend-based cryptography protocols via a free-space optical link.
	Multiphoton entanglement Complex quantum information protocols can be based on multiphoton entanglement. We investigate preparation of such states via parametric down conversion with femtosecond pump pulses.
	Quantum state estimation Optical quantum communication and measurements require often complete quantum state estimation. Our minimal polarimeter topologies allow efficient tomography of single and multiphoton states.

Quantum optics group