🚀 go-pugleaf

I woke up this morning realizing that, of course, if the two beams into the
splitter ar coherent and 90 degrees out of phase then one output port will
have no signal due to constructive interference because of extra 90 degree
shift of splitter. In this special circumstance splitter is not
"irreversible". But his trick can be used to get a single |h> in my
experiment.  Put a 90 degree shift phase plate in path of one output of
first recombiner then use second beamsplitter so that all of the signal
goes to only one counter.  Now Ramsay don't say we have to worry about
phase variations because lots of interferometers work this way.  For
example, a Mach-Zehnder.