用标准驯服量子.pdf

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1、Dr Richard Pitwon,SeagatePutting Quantum into PracticePutting Quantum into PracticeDr Richard Pitwon,SeagateFTS:QUANTUMDr Richard PitwonSPutting Quantum into PracticeMosca Equation How long is your information required to be secure(x years)?How long to retool existing infrastructure with quantum saf

2、e or resistant solutions(y years)How long until a large scale quantum computer is built(z years)?Moscas TheoremIf x+y z Then worryy yx xz zCharles H.Bennett and Gilles Brassard invented the first quantum cryptography protocol in 1984.BB84 ProtocolBB84 BB84 uses the polarization states of photons to

3、transmit information.The sender(traditionally referred to as Alice)and the receiver(Bob)are connected by a quantum communication channel which allows quantum states to be transmitted.In the case of photons this channel is generally either an optical fiber or simply free space.In addition they commun

4、icate via a public classical channel,for example using broadcast radio or the internet.BB84 uses the polarization states of single photons to transmit informationCharles H.Bennett and Gilles Brassard invented the first quantum cryptography protocol in 1984.BB84 ProtocolRectilinear Basis+Bit01Diagona

5、l Basis x01SymbolAngle09045Encoding qubits into four polarisations on two orthonormal basesEach pair of orthogonal polarization states is called a Basis.BB84 uses two bases,with each pair“conjugate”to the other pair.That means you cannot distinguish between all four states in one measurement.8Alices

6、 random bit0Alices random sending basis+Photon polarization Alice sendsBobs random measuring basis+Photon polarization Bob measuresCorresponding bit received by Bob0Step 1Alice chooses a random bit(0)and a random sending basis(+).Bob chooses a random measuring basis(+).Alice sends this photon to Bob