Method and apparatus for distributing a quantum key

Abstract

A method for distributing a quantum key is provided, including sending a first photon to a first receiver; sending a second photon to a second receiver, the first and second photons being a pair of time-energy entangled photons; and providing a coding scheme comprising a plurality of time bins and a plurality of frequency bins, wherein a combination of a time bin and a frequency bin corresponds to a character.

1 .- 9 . (canceled) 
     
     
         10 . An apparatus for receiving a quantum key, comprising:
 a channel configured to receive photons;   a plurality of multi-channel filtering elements, each corresponding to a frequency and each configured to pass photons within a range of its corresponding frequency; and   a plurality of photon detectors, each configured to receive photons passed by one of the plurality of multi-channel filtering elements and to send an indication of arrival time of photon detection for each frequency range.   
     
     
         11 . The apparatus of  claim 10 , wherein the multi-channel filtering element comprises a grating. 
     
     
         12 . The apparatus of  claim 10 , wherein the multi-channel filtering element comprises a dispersive element. 
     
     
         13 . The apparatus of  claim 10 , further comprising a laser and a non linear crystal. 
     
     
         14 . The apparatus of  claim 13 , wherein the non linear crystal generates pairs of photons by spontaneous parametric down conversion. 
     
     
         15 . The apparatus of  claim 14 , wherein the pairs of photons are time-energy entangled photon pairs. 
     
     
         16 . The apparatus of  claim 10 , wherein the photons are sent via a photonic integrated chip. 
     
     
         17 . The apparatus of  claim 10 , wherein the photons are sent via optical fiber. 
     
     
         18 . An apparatus for receiving a quantum key, comprising:
 a channel configured to receive photons;   a plurality of multi-channel filtering elements, each corresponding to a frequency and each configured to pass photons within a range of its corresponding frequency; and   a plurality of photon detectors, each configured to receive photons passed by one of the plurality of multi-channel filtering elements and to determine a time bin based on the arrival time of photon detection and frequency range.   
     
     
         19 . The apparatus of  claim 18 , wherein the multi-channel filtering element comprises a grating. 
     
     
         20 . The apparatus of  claim 18 , wherein the multi-channel filtering element comprises a dispersive element. 
     
     
         21 . The apparatus of  claim 18 , further comprising a laser and a non linear crystal. 
     
     
         22 . The apparatus of  claim 21 , wherein the non linear crystal generates pairs of photons by spontaneous parametric down conversion. 
     
     
         23 . The apparatus of  claim 22 , wherein the pairs of photons are time-energy entangled photon pairs. 
     
     
         24 . The apparatus of  claim 18 , wherein the photons are sent via a photonic integrated chip. 
     
     
         25 . The apparatus of  claim 18 , wherein the photons are sent via optical fiber. 
     
     
         26 . A communication system for distributing a quantum key, comprising:
 a laser and a non linear crystal adapted to generate pairs of photons by spontaneous parametric down conversion.   a first apparatus comprising
 a first channel configured to receive photons; 
 a first plurality of multi-channel filtering elements, each corresponding to a frequency and each configured to pass photons within a range of its corresponding frequency; and 
 a first plurality of photon detectors, each configured to receive photons passed by one of the plurality of multi-channel filtering elements and to send an indication of arrival time of photon detection for each frequency range; and 
   a second apparatus comprising
 a second channel configured to receive photons; 
 a second plurality of multi-channel filtering elements, each corresponding to a frequency and each configured to pass photons within a range of its corresponding frequency; and 
 a second plurality of photon detectors, each configured to receive photons passed by one of the plurality of multi-channel filtering elements and to send an indication of arrival time of photon detection for each frequency range; and