  Interacting Bosons, loaded in artificial lattices, have emerged as a modern
platform to explore collective manybody phenomena, quantum phase transitions
and exotic phases of matter as well as to enable advanced on chip simulators.
Such experiments strongly rely on well-defined shaping the potential landscape
of the Bosons, respectively Bosonic quasi-particles, and have been restricted
to cryogenic, or even ultra-cold temperatures. On chip, the GaAs-based
exciton-polariton platform emerged as a promising system to implement and study
bosonic non-linear systems in lattices, yet demanding cryogenic temperatures.
In our work, we discuss the first experiment conducted on a polaritonic lattice
at ambient conditions: We utilize fluorescent proteins as an excitonic gain
material, providing ultra-stable Frenkel excitons. We directly take advantage
of their soft nature by mechanically shaping them in the photonic
one-dimensional lattice. We demonstrate controlled loading of the condensate in
distinct orbital lattice modes of different symmetries, and finally explore, as
an illustrative example, the formation of a gap solitonic mode, driven by the
interplay of effective interaction and negative effective mass in our lattice.
The observed phenomena in our open dissipative system are comprehensively
scrutinized by a nonequilibrium model of polariton condensation. We believe,
that this work is establishing the organic polariton platform as a serious
contender to the well-established GaAs platform for a wide range of
applications relying on coherent Bosons in lattices, given its unprecedented
flexibility, cost effectiveness and operation temperature.
