Merging Phase Modulation from 2.1.0

[eightfifteenthspisquared]

We have one remaining pull request from DISSCO 2.1.0 about phase modulation. That should be merged into here when possible. This also needs further testing tipei/DISSCO-2.1.0#9

[DiyunZ]

See https://github.com/cmp-illinois/DISSCO/tree/PhaseModulationTest