Photons – the elementary quanta of light – are essentially devoid of interactions, which makes them ideal carriers of information. In fact, our ability to generate, control and detect light has not only revolutionized modern telecommunication, but has had a broad impact on science and society, from remote sensing in meteorology and climatology, over optical tomography in biomedicine to the recent detection of gravitational waves.
Yet, the possibility to exploit quantum mechanical phenomena for such tasks is opening up entirely new horizons. Indeed, quantum effects, such as coherence, quantum superposition and quantum entanglement constitute the underlying principles for future optical technologies that may, for example, enable quantum-enhanced imaging, fundamentally secure communication and quantum computing. All of this requires the quantum control of light, i.e. the ability to generate and manipulate light at the level of single photons. With the inherent lack of photon interactions, this ultimate form of optical control has remained a grand challenge and constitutes the ambitious goal of the novel research field of quantum nonlinear optics.
Here, interaction of single photons with matter and saturation of individual quantum emitters is combined to realize nonlinear optical media which response depends on the exact number of photons inside the medium. The resulting few-photon nonlinearity is equivalent to an effective interaction between individual photons, which can be exploited to realize photonic quantum technology building blocks as well as highly controllable few- and many-body systems of strongly correlated photons.
This seminar, which will bring together about 80 participants in March 2023, will provide a comprehensive overview of the different platforms and approaches of this rapidly developing field. Leading international experts review the present status of the control of light photon by photon and the prospects of strongly correlated quantum many-body states of photons, from both the experimental and theoretical point of view. The workshop in particular aims to highlight future trends and perspectives. Participants are invited to present their current research in the poster sessions. In addition, outstanding contributions are selected for contributed talks.

The conference language will be English. The Wilhelm and Else Heraeus-Foundation bears the cost of full-board accommodation for all participants.