So, I've decided to talk about quantum communication today.
QUANTUM COMMUNICATION, DESCRIPTION & APPLICATION
I'll keep this simple because I don't think it is wise explain quantum communication from fundamentals because that would be like teaching arithmetic by starting with number theory.
Some simple definitions before we build a quantum communication system:
[Bit]: the smallest unit of information which can be either 0 OR 1 state.
[QBit]: the smallest unit of quantum information that is in both 0 AND 1 state (superposition|entanglement).
[Carrier]: the physical implementation of a (Q)Bit
[Communication]: the exchange of bit(s) of information between 2 or more things.
FASTER THAN LIGHT COMMUNICATION TO MARS:
Step 1 create QBits by using light as a carrier with horizontal and vertical polarization in superposition
Step 2 split the light into 2 beams and store one and send the other to Mars
Step 3 either build a store of QBits or maintain a constant stream
Step 4 receive information by detecting a QBit state as either 0 or 1.
Step 5 send information by forcing a QBit state to either 0 or 1.
Sending the initial QBits must be done slower or at light speed (13-24 minutes to mars). Once the QBits have arrived, there is literally zero latency. Each bit of information used for communication causes one QBit to be decohered and fixed into a known state. It would happen simultaneously on earth, mars and is what Einstein referred to as 'spooky action at a distance. In practice, mars would be sent a constant supply of QBits whenever convenient and they would be stored until needed for communication. That means a call to mars would be instantaneous, with no pauses between speaking and waiting for reply - as long as the total QBit supply isn't exhausted.
There are technical details such as:
How can QBits be transmitted?
How can QBits be stored?
How can you detect if a QBit is used(decohered) or not?
How can a QBit be forced to decohere into a specific state?
How is error correction handled?
There are answers to each of these questions, they are beyond what I am trying to explain here.
I have show how quantum communication works in the space dimension, now I'll show how it works in the time dimension:
INSTANTANEOUS COMMUNICATION WITH THE FUTURE:
Step 1 create QBits using a durable magnetic or optical medium
Step 2 maintain the QBit medium in a coherent state for 17 years
Step 3 receive information from a future sender by detecting a QBIT state as either 0 or 1.
Step 5 send information to the future by forcing a QBit state to either 0 or 1.
Step 6 periodically add QBits to storage medium if they are expended.
As you can see, there is little important difference between Quantum communication across space or time. A different QBit carrying medium is required. Perhaps counter intuitively, a QBit just stored for a future 17 years from now could IMMEDIATELY be used to receive information from that future. It primarily requires that the connection WILL BE/HAS BEEN maintained. In fact an initial check would probably be done as a HANDSHAKE protocol to verify connection has been established.
Standard error correction and transmission protocols can be applied to any bi-directional information stream with no changes required. With enough QBit 'bandwidth', it is entirely feasible to control machines, send text, make calls, browse web pages, or watch movies from either mars or the future. In fact, both time and space can be combined with no penalty so watching movies from Mars in the future is equally possible.
The basic operations for quantum communication are:
-creating QBits
-storing QBits
-transmitting QBits
-detecting coherence(used/unused) state
-detecting Qbit state as 0 or 1 (to receive)
-forcing Qbit state to 0 or 1 (to send)
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