If zombies are logically possible, then surely it must be logically possible that one day I am a zombie, then the next day I have qualia, then the next I am a zombie etc.
This logically follows from the premises; that the physical world is causally closed, that qualia are not identical (or reducible) to physical states, so therefore they can be absent or present, but the physical processes will go on as normal.
If I can have alternating qualia from day to day then I can have them alternating from minute to minute, or second to second.
But I could not have qualia alternating from second to second, and still have the same behavior. I would notice the “lights flashing,” and say something about it.
Therefore zombies are not logically possible.