WOLFRAM|DEMONSTRATIONS PROJECT

Superdense Coding

​
message (​
B
2
B
1
​)
(
0
0
)
(
0
1
)
(
1
0
)
(
1
1
)
In superdense coding, a sender (Alice) can send a message consisting of two classical bits using one quantum bit (qubit) to the receiver (Bob). The input to the circuit is one of a pair of qubits entangled in the Bell basis state (the upper qubit). The other qubit from the pair (the lower qubit) is sent unchanged to Bob. After processing the upper qubit in one of four ways, it is sent to Bob, who measures the two qubits, yielding two classical bits. The result is that Bob receives two classical bits,
B
1
and
B
2
, that match those that Alice sent, but only a single (upper) qubit conveyed those two bits of information.