| 摘要 |
Apparatus for distributing a quantum key between nodes Alice and Allie, comprising a coupler that splits generated photon pulses into first and second pulses P 1 and P 2; and an interface that transmits the P 1 's and P 2 's into a network. The P 1 's are received after modulation by Alice with respective phases selected from two encoding bases and further selected from within the selected encoding basis as a function of a bit value of a respective bit in a key bit string maintained by Alice. The P 2 's are received after similar modulation by Allie. A detector processes the P 1 's and P 2 's upon receipt to produce a sequence of detection outcomes indicative of phase mismatch between the P 1 's and corresponding P 2 's. A control unit receives an indication of occurrences of a match between the encoding bases employed by Alice and the encoding bases employed by Allie, derives an XOR bit string from those detection outcomes that are associated with occurrences of a match, and communicates the XOR bit string to Alice and/or Allie. Execution of an XOR between the XOR bit string and either Alice's or Allie's key bit string allows the two participants to form a shifted key.
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