Autocompensating quantum cryptographic key distribution system based on polarization splitting of light
US6188768A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 31, 1998 |
| Grant date | Feb 13, 2001 |
| Priority date | — |
| Expiry date | Mar 31, 2018 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L9/0858
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A quantum cryptographic key distribution (QKD) system splits discrete light signals from a laser source into a pair of light pulses that are orthogonally polarized with respect to each other, imparts a phase shift to one or both of these separate pulses during their round trip from the sender to the receiver and back, assures that the return pulses from the receiver are attenuated to single-photon pulses, recombines the phase-shifted pulses at the sender, and then detects from the recombined signal its polarization state, which is representative of the net phase shift imparted by the sender and receiver. The phase modulator at the receiver transmits only one polarization (e.g., vertical), but is used in a manner that permits it to equally modulate both polarization components of an arriving pulse. In this arrangement, when both components of a pulse reach the phase modulator at the receiver, they are both entirely vertically polarized and a phase shift is imparted at that time. This has the advantage that the effect of any time variation or phase errors in the phase modulator will be the same on both components. The key information is decoded at a detection stage at the sender that…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.