Diagram/setting: https://i.redd.it/1hyw05yunb6b1.png

There are lots of microscopic CPT tests (
https://arxiv.org/pdf/0801.0287 ), but it seems there is missing a real
macroscopic one (?) - test if CPT analogue of a setting works as it
should.

The diagram show such proposed test - this symmetry suggests existence
of looking unknown effect e.g. for ring laser, with potentially lots of
new applications (like quantum computing) - increase probability of
directional deexcitation of target.

I am searching for access to one/collaboration to test its
existence. Negative effect would be also interesting as suggesting
macroscopic violation of CPT symmetry. Please contact me if interested.

Ring lasers allow for nearly unidirectional photon trajectories. Looking
from perspective after applied CPT symmetry to the shown setting,
photons would travel in the opposite direction - causing excitation of
the target (lamp).

Going back from CPT to to the original perspective, the above means
laser causes deexictation of the target. (lamp continuously excited in
corresponding spectrum, increased probability of directional
deexcitation in addition to standard isotropic radiation).