System and methods for quantum key distribution over wdm links

Abstract

A system and a method for quantum key distribution between a transmitter and a receiver over wavelength division multiplexing (WDM) link are disclosed. The method includes providing one or more quantum channels and one or more conventional channels over the WDM link; assigning a different wavelength to each of the one or more quantum channels and each of the one or more conventional channels; transmitting single photon signals on each of the one or more quantum channels; and transmitting data on each of the one or more conventional channels. The data comprises either conventional data or trigger signals for synchronizing the transmission of the single photon signals on the quantum channels. All channels have wavelengths around 1550 nm. The WDM link can be a 3-channel WDM link comprising two quantum channels for transmitting single photon signals and one conventional channel for transmitting conventional data or triggering signals.

1 . An apparatus comprising:
 a transmitting unit comprising:
 a detector configured to generate a first trigger signal in response to detection of a portion of a light pulse that triggers modulation of a single photon signal, the single photon signal being one of a plurality of modulated single photon signals indicative of quantum key information, and wherein the detector is further configured to generate the first trigger signal with a delay to synchronize a phase shift; and 
 a Faraday mirror configured to generate a reflected portion of the light pulse. 
   
     
     
         2 . The apparatus of  claim 1 , wherein the detector is further configured to receive the light pulse via a conventional channel. 
     
     
         3 . The apparatus of  claim 2 , wherein the transmitting unit further comprises a splitter configured to generate at least a portion of the light pulse from the light pulse received via the conventional channel. 
     
     
         4 . The apparatus of  claim 1 , wherein the transmitting unit further comprises an attenuator configured to attenuate a laser signal into the one of the plurality of modulated single photon signals. 
     
     
         5 . The apparatus of  claim 1 , further comprising an array waveguide grating configured to multiplex a plurality of quantum channels and a conventional channel. 
     
     
         6 . A method, comprising:
 receiving, at a plurality of quantum receivers via a plurality of quantum channels, a plurality of modulated single photon signals, wherein the plurality of modulated single photon signals are indicative of quantum key information imposed by a plurality of modulators at a transmitter, and wherein the receiving the plurality of modulated single photon signals comprises compensating for errors.   
     
     
         7 . The method of  claim 6 , wherein the compensating comprises compensating for errors experienced during transmission of at least one of the plurality of modulated single photon signals. 
     
     
         8 . The method of  claim 6 , further comprising: multiplexing the plurality of quantum channels and a conventional channel in a wavelength division multiplexing link. 
     
     
         9 . The method of  claim 6 , wherein wavelengths assigned to the plurality of quantum channels and a conventional channel range from approximately 1,475 nanometers (nm) to approximately 1,590 nm. 
     
     
         10 . The method of  claim 6 , further comprising:
 initiating a first light pulse and a second light pulse; and   transmitting, via at least one of the plurality of quantum channels, the first light pulse and the second light pulse for use by a transmitter and to generate at least one of the plurality of modulated single photon signals.   
     
     
         11 . The method of  claim 6 , further comprising:
 generating an interference signal in response to at least one of the plurality of modulated single photon signals.   
     
     
         12 . The method of  claim 11 , further comprising:
 extracting a quantum key based on the interference signal.   
     
     
         13 . An apparatus, comprising:
 means for receiving, via a plurality of quantum channels, a plurality of modulated single photon signals, wherein the plurality of modulated single photon signals are indicative of quantum key information imposed by a plurality of modulators, and wherein the means for receiving the plurality of modulated single photon signals comprises means for compensating for errors experienced during transmission of at least one of the plurality of modulated single photon signals; and   means for multiplexing the plurality of quantum channels and a conventional channel.   
     
     
         14 . The apparatus of  claim 13 , further comprising:
 means for receiving, via the conventional channel, a reflected portion of a light pulse that generates a trigger signal that triggers synchronization.   
     
     
         15 . The apparatus of  claim 13 , further comprising:
 means for transmitting the plurality of quantum channels and the conventional channel at wavelengths ranging from approximately 1,475 nanometers (nm) to approximately 1,590 nm.   
     
     
         16 . The apparatus of  claim 13 , wherein the means for receiving includes means for receiving the plurality of quantum channels and the conventional channel at wavelengths ranging from approximately 1,475 nanometers (nm) to approximately 1,590 nm. 
     
     
         17 . The apparatus of  claim 13 , further comprising:
 means for generating an interference signal based on at least one of the plurality of modulated single photon signals; and   means for extracting a quantum key based on the interference signal.   
     
     
         18 . A computer-readable storage medium having instructions stored thereon that, in response to execution, cause an apparatus to perform operations, comprising:
 receiving, via a plurality of quantum channels, a plurality of modulated single photon signals indicative of quantum key information imposed by a plurality of modulators; and   compensating for errors experienced during transmission of at least one of the plurality of modulated single photon signals.   
     
     
         19 . The computer-readable storage medium of  claim 18 , the operations further comprising:
 multiplexing, by wavelength, a conventional channel and the plurality of quantum channels.   
     
     
         20 . The computer-readable storage medium of  claim 18 , the operations further comprising:
 attenuating a laser signal into the at least one of the plurality of modulated single photon signals.