Lecture: Quantum optics and information science in multi-dimensional photonics networks

07.11.2016, 10:00

Prof. Christine Silberhorn Integrated Quantum Optics, Department Physics, Paderborn University

Monday, November 7th 2016, 10:00h

Seminar Room A1.500, Staudtstr. 2, 91058 Erlangen

Abstract:

Classical optical networks have been widely used to explore a broad range of transfer phenomena based on coherent interference of waves, which relate to different disciplines in physics, information science, and even biological systems. At the quantum level, the quantized nature of light, this means the existence of photons and entangled states, gives rise to genuine quantum effects that can appear completely counter-intuitive. Yet, to date, quantum network experiments typically remain very limited in terms of the number of photons, reconfigurability and, maybe most importantly, network size and dimensionality.

 

Photonic quantum systems, which comprise multiple optical modes as well as highly non-classical and sophisticated quantum states of light, have been investigated intensively in various theoretical pro­posals over the last decades. However, their implementation requires advanced setups of high complexity, which, to date, poses a considerable challenge on the experimental side. The successful realization of controlled quantum network structures is key for many applications in quantum optics and quan­tum information science.

 

Here we present three differing approaches to overcome current limitations for the experimental implementation of multi-dimensional quantum networks. The development of non-linear, integrated quantum devices with multiple channels allows us to combine several functionalities on a single monolithic structure and thus highly efficient multi-channel sources for tailored multi-photon states become available.

We have recently introduced the framework of photon temporal modes of ultrafast pulsed quantum light as a new platform for quantum information science applications. These temporal modes are defined as sets of field orthogonal superposition states of pulsed light of different shapes and span a high-dimensional Hilbert space. Because they occupy only one single spatial mode, they also lend themselves to integration into current single-mode fiber communication networks.

 

Finally, we have been pioneering the concept of time-multiplexed quantum walks. The use pulsed light in combination with designed fibre loop geometries allows us to realize different types of photonic quantum walks as a test-bed for the simulation of quantum propagation phenomena. The flexibility and reconfigurability of our setup enables us to investigate different dynamical behaviours and graph structures in the walk, while the realization of the step operator in the temporal domain pro­vides superior coherence properties for the realization of large-scale quantum networks.