I recently learned that the state of an entangled particle can be
repeatedly measured without changing or destroying it, i.e. without using a
detector that converts the particle to electrical signals as a means
of detection. This website describes the technique called Quantum Nondemolition. I have a few questions for anyone who is qualified to answer:
1. Does this mean that Shannon's Law no longer applies, since a single
photon can be used multiple times to communicate a bit of information?
What is the new law governing maximum bitrate per channel ?
2. Since quantum states can be communicated without a line-of-sight,
does this mean that we can dispense with giant high-accuracy targeting
mirrors, e.g. for laser communication? Shouldn't the information simply find
it's way to the detector in some spooky fashion, without need to point
an antenna in its direction?
3. Does communication by quantum non-demolition teleportation imply
that energy is being transmitted? For example, could I generate
electricity in a lab, use it to alternate the states of entangled
particles, and thereby supply power to a similarly connected device at
a great distance without a line-of-sight? For example, could I supply
power to a spacecraft from a ground station without any conventional
transmitter?
Quantum Non-Demolition (question for a physicist)
