Superdense coding is a very cool protocol! It allows to securely transfer two classical bits of information by only sending one qubit (even though, you need a previously shared entangled pair)!
It is quite a hard protocol to describe in detail, but I will try it using its quantum circuit
Let us suppose that Alice wants to send securely two classical bits to Bob.
The protocol reads as follow:
A comment: to transmit two bits, there is an exchange of a qubit and nothing else, no communication of any sort.
Moreover, it is a secure protocol because if anybody else would intercept Alice's qubit, this malicious actor could not retrieve enough information to know the message. Yet Bob would not receive it, too, but the secrecy of the message is not compromised.
In a blockchain perspective, it could be used to transmit information (keys, transactions, etc.) without an actual message to be eavesdropped. Nonetheless, there are even more sophisticated algorithms and protocols to achieve this result. In this context, superdense coding can be considered a starting point.
That's all for today!
Stay tuned and see you in the next post! We will meet with the most groundbreaking quantum algorithm: SHOR'S ALGORITHM!
@maar to stay updated and to know more about the fascinating world of Quantum Information and Computation!