U2L1c.txt

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I'm going to explain superdense coding,
and then I'll go into the details of teleportation.
So superdense coding-- so Alice has 2 bits.
And she wants to send them to Bob.
So Alice and Bob, again, have an EPR pair.

And what Alice does is she encodes
the 2 qubits in her half of the EPR pair, which is 1.
She encodes the 2 bits in her half of the EPR pair,
which is 1 qubit.
She sends this to Bob.
And Bob takes the--
now Bob does a joint measurement, measurement,
and he recovers the 2 bits.

And this doesn't seem anywhere near as miraculous as this.
But if you go back to 1973, Alexander Holevo in Russia
proved that 1 qubit can only transmit 1 bit of information.
So your transmitting twice as much information as, you know,
theoretically possible without the EPR pair with 1 qubit.
So that's why it's called superdense coding.