Patent ID: 7920704
Filing Date: 2011-04-05
Classification: H04L

Abstract:
1. A system for eavesdropping on a four state quantum key distribution protocol, comprising: providing a quantum cryptographic entangling probe comprising: a single-photon probe creator for the purpose of eavesdropping on quantum key distribution; a photon polarization state filter to tune the polarization state of the probe photon produced by said single photon probe creator to the photon polarization state for a set error rate induced by the quantum cryptographic entangling probe; a quantum controlled-NOT (CNOT) gate configured to provide entanglement of a signal photon polarization state with the probe photon polarization state and produce a gated probe photon so as to obtain information on a key; a Wollaston prism in communication with said CNOT gate configured to separate the gated probe photon with polarization correlated to a signal measured by a legitimate receiver; and two single-photon photo detectors for the purpose of eavesdropping on quantum key distribution in communication with said Wollaston prism configured to measure the polarization state of the gated probe photon.