Photon generator

Abstract

Briefly stated, the invention provides an apparatus for quantum computing comprising optical integrated on-chip generation of photon pairs as building blocks to create entangled photon states which are detected as necessary for quantum information processing. The invention provided a frequency selective optical coupling device which controls the transmission of light by varying the relative dimensions of otherwise symmetrical linear optical waveguides tangential to an annular optical waveguide, thereby controlling the coupling of light between the linear optical waveguides and the annular optical waveguide. Dimensional change of the optical waveguides is achieved by a heated medium in proximity of the optical waveguides and under electronic control.

What is claimed is: 
     
         1 . A quantum computation device, comprising:
 a plurality of photon generators, each   photon generator further comprising:
 a ring resonator disposed in a chip; 
 a first optical channel disposed in said chip, said first optical channel having a first input and a first output, said first input and said first output being in common with each other and with said input to said chip;
 said first optical channel being tangential to said ring resonator at a first point and a second point; and 
 
 a second optical channel disposed in said chip, said second optical channel having a second input and a second output;
 said second optical channel being tangential to said ring resonator at a third point and a fourth point; 
 
   a first plurality of optical couplers, each optical coupler corresponding to one of said plurality of photon generators in a one-to-one fashion for coupling said second input and said second output of said photon generator so as to produce entangled photon states;   a reconfigurable optical switch network for matrixing connections between outputs of said first plurality of optical couplers and inputs of a second plurality of optical couplers;   a second plurality of optical couplers, each corresponding to and each being reconfigurably connected via said reconfigurable optical switch network to any one of said first plurality of optical couplers;   a third plurality of optical couplers, each connected to each of a corresponding second plurality of optical couplers so as to further entangle said photon states;   phase shifting elements
 between each of said plurality of photon generators and each of said corresponding first plurality of optical couplers; and 
 between each of said second plurality of optical couplers and each of said corresponding third plurality of optical couplers so as to compensate for optical length and timing differences; and 
   a plurality of photodetectors for indicating said entangled photon states output from said third plurality of optical couplers so as to facilitate computations therefrom.   
     
     
         2 . (canceled) 
     
     
         3 . (canceled) 
     
     
         4 . The quantum computation device of  claim 1 , wherein said photon generators each further comprise:
 a first filter having an output for selecting spectrally degenerate photons from said second input of said second optical channel;   a second filter having an output for selecting spectrally degenerate photons from said second output of said second optical channel;   a first predeterminable relative phase delay between said first optical channel and said second optical channel, so as to cause a variance in an amount of light traversing said first optical channel and said second optical channel as a function of the frequency of said light;   a second predeterminable relative phase delay between said second input of said second optical channel and said second output of said second optical channel;   at least one filter of a third filter group having an output in common with a first output of said plurality of outputs of said chip, where said at least one filter of said third filter group selects predetermined wavelengths of light from said phase delayed second input of said second optical channel;   at least one filter of a fourth filter group each having an output in common with a second output of said plurality of outputs of said chip, where said at least one filter of said fourth filter group selects predetermined wavelengths of light from said phase delayed second output of said second optical channel;   a third predeterminable relative phase delay between said first filter output and said second filter output;   an optical coupling between said relative phase delayed first filter output and said relative phase delayed second filter output, said optical coupling having a first output and a second output;   a third output of said plurality of outputs of said chip in common with said phase delayed second input of said second optical channel;   a fourth output of said plurality of outputs of said chip in common with said phase delayed second output of said second optical channel;   a fifth output of said plurality of outputs of said chip in common with said first output of said optical coupling;   a sixth output of said plurality of outputs of said chip in common with said second output of said optical coupling; and   an electronic control subsystem in operative communication with said chip for facilitating said predeterminable relative phase delays.   
     
     
         5 . The quantum computation device of  claim 1 , wherein said tangentiality permits a coupling of light between said ring resonator and said optical channels at said first, said second, said third and said fourth points. 
     
     
         6 . The quantum computation device of  claim 4 , wherein said first predeterminable relative phase delay is induced by a relative difference in length between said first optical channel and said second optical channel. 
     
     
         7 . The quantum computation device of  claim 4 , wherein said second predeterminable relative phase delay is induced by a relative difference in the length of optical channel from said second input to said third output, and the length of optical channel from said second output to said fourth output. 
     
     
         8 . The quantum computation device of  claim 4 , wherein said third predeterminable relative phase delay is induced by a relative difference in the length of optical channel from said first filter output to said optical coupling, and the length of optical channel from said second filter output to said optical coupling. 
     
     
         9 . The quantum computation device of  claim 6 , wherein said relative difference in length is induced by thermal expansion further induced by a heated medium in proximity of said optical channels. 
     
     
         10 . The quantum computation device of  claim 7 , wherein said relative difference in length is induced by thermal expansion further induced by a heated medium in proximity of said optical channels. 
     
     
         11 . The quantum computation device of  claim 8 , wherein said relative difference in length is induced by thermal expansion further induced by a heated medium in proximity of said optical channels. 
     
     
         12 . The quantum computation device of  claim 4 , where said first and said second filters are ring resonator filters. 
     
     
         13 . The quantum computation device of  claim 1 , wherein each of said plurality of photon generators comprises a ring resonator on a chip of nonlinear optical material; said ring resonator having two connections of an optical waveguide or channel on each side of said ring resonator such that each said side forms an asymmetric length Mach-Zehnder interferometer to filter pump light from signal/idler photons created in said nonlinear optical material ring resonator; inside said ring resonator pump photons are critically coupled into said resonator to facilitate maximum generation of said signal/idler photons in said nonlinear optical material ring resonator and which remain in a cavity inside said ring resonator; said signal/idler photons generated in said nonlinear optical material based ring resonator by the process of either spontaneous parametric downconversion and spontaneous four wave mixing are over coupled to said resonator cavity to allow for maximum brightness of generated signal/idler photons exiting said nonlinear optical material-based ring resonator while said pump photons remain in said ring resonator cavity.