  Topological features - global properties not discernible locally - emerge in
systems from liquid crystals to magnets to fractional quantum Hall systems.
Deeper understanding of the role of topology in physics has led to a new class
of matter: topologically - ordered systems. The best known examples are quantum
Hall effects, where insensitivity to local properties manifests itself as
conductance through edge states that is insensitive to defects and disorder.
Current research in engineering topological order primarily focuses on
analogies to quantum Hall systems, where the required magnetic field is
synthesized in non-magnetic systems. Here, we realize synthetic magnetic fields
for photons at room temperature, using linear Silicon photonics. We observe,
for the first time, topological edge states of light in a two - dimensional
system and show their robustness against intrinsic and introduced disorder. Our
experiment demonstrates the feasibility of using photonics to realize
topological order in both the non-interacting and many-body regimes.
