Synthetic Non-Hermitian Photonic Structures: Recent Results and Future Challenges

For this workshop, the Max Planck Institute welcomed a diverse group of 52 participants
from all inhabited continents, representing leading experimental and theoretical groups that
work on the fundamental and applied aspects in gain/loss engineered optical and quantum-
optical systems, as well as extensions to analogous physical settings.

Under the general theme of non-hermitian physics, the workshop covered new devel-
opments in the research of Parity-time reversal symmetry, Exceptional points, Topological
eects, Supersymmetry, Nonlinear interactions, Unidirectional invisibility, Microlasers and
Optical sensors.

Theses issued were covered by 24 invited speakers, representing roughly in equal parts
closely interconnected experimental and theoretical activities and including the founding g-
ure of the eld, Max-Born medalist Demetrios Christodoulides (University of Central Florida,
Orlando), as well contributed talks and a very lively poster session highlighting the impor-
tant contributions of the junior participants. Professor Christodoulides also delivered an
inspiring colloquium on thermodynamic interpretations of multimode propagation in optical
bres.

Of particular note transpiring through all contributions was the rapidity in which novel
theoretical ideas nd their way into experimental realizations and practical applications.
Throughout the workshop, this was emphasized in the dedicated discussions over the breaks
and continuing into the evening, where participants forged new links and exchanged ideas,
thereby signicantly shaping the future course of this active eld. Examples include the
upcoming realization of supersymmetric lasers and the pursuit of higher-order degeneracies,
topological robustness, time-domain realizations and quantum-optical ngerprints of nonher-
mitian symmetries, as well as the transferal of ideas to phononic, polaritonic and electronic
settings and systems operating in the THz regime.