Claims
- 1. A QKD method, comprising:
determining initial QKs, initial QKA and initial QKB; determining an initial QKA value of a first function applied to said initial QKA, wherein a value of said first function depends upon values of specified information unit of a QK, including bit i; determining an initial QKB value of said first function applied to said initial QKB; and forming a revised QKA by depending a value of an information unit of said revised QKA on a value of information unit i of said initial QKA, if said initial QKA value equals said initial QKB value.
- 2. The method of claim 1 wherein said information unit is a continuous variable.
- 3. The method of claim 1 wherein said information unit is a discrete variable.
- 4. The method of claim 1 wherein said information unit is a digital bit value.
- 5. The method of claim 1 wherein said first function depends upon at least two information units of a QK.
- 6. The method of claim 1 further comprising forming a revised QKB by depending a value of bit of said revised QKB on a value of bit i of said initial QKB, if said initial QKA value equals said initial QKB value.
- 7. The method of claim 1 wherein said revised QKA includes a smaller number of bits than said initial QKA.
- 8. The method of claim 1 further comprising forming said revised QKA not depending upon a value of bit i of said initial QKA if said initial QKA value does not equal said initial QKB value.
- 9. The method of claim 1 further comprising determining a second function initial QKA value of a second function applied to said initial QKA, wherein a value of said second function depends upon values of specified bits of a QK, including bit j, j not equal to i;
determining a second function initial QKB value of said second function applied to said initial QKB; and forming said revised QKA by depending a value of a bit of said revised QKA on a value of bit j of said initial QKA, if said second function initial QKA value equals said second function initial QKB value.
- 10. The method of claim 1, further comprising:
selecting a fraction of errors between said initial QKA and said initial QKB to be corrected; depending a dimension of a first code upon said percentage; and approximating a revised QKB using said first code.
- 11. The method of claim 10 further comprising applying a second code based upon function of a word in said first code and a second code to define a final code.
- 12. The method of claim 1 wherein a fraction of errors between QKA and QKB that is corrected is greater than 11 percent.
- 13. A computer system for performing QKD, comprising:
means for determining initial QKs, initial QKA and initial QKB; means for determining an initial QKA value of a first function applied to said initial QKA, wherein a value of said first function depends upon values of specified information unit of a QK, including bit i; means for determining an initial QKB value of said first function applied to said initial QKB; means for forming a revised QKA by depending a value of an information unit of said revised QKA on a value of information unit i of said initial QKA; and means for depending said means for forming on whether said initial QKA value equals said initial QKB value.
- 14. A QKD method, comprising:
determining initial QKs, initial QKA and initial QKB, each initial QK consisting of a series of information units, each information unit of each QK having one value of a set of defined values; performing on said initial QKA a third function to generate a QKA third function value; performing on said initial QKB said third function to generate a QKB third function value; wherein:
(1) said third function depends upon values of at least two bits of a QK and (2) said third function has only one of said defined values; and forming a revised QKA by setting a value of a bit of said revised QKA equal to said QKA third function value.
- 15. The method of claim 14 wherein said set of defined values are continuous real numbers.
- 16. The method of claim 14 wherein said set of defined values are a finite set of discrete values.
- 17. The method of claim 14 wherein said set of defined values are digital bit values.
- 18. The method of claim 14 wherein said third function depends upon at least two information units of a QK.
- 19. The method of claim 14 further comprising forming a revised QKA by setting a value of an information unit of said revised QKA equal to said QKA third function value.
- 20. The method of claim 14 further comprising performing on said initial QKA a fourth function to generate a QKA fourth function value;
performing on said initial QKB said fourth function to generate a QKB fourth function value; wherein:
(1) said fourth function depends upon values of at least two bits of a QK and (2) said fourth function has only one of said defined values; and forming said revised QKA by setting a value of a bit of said revised QKA equal to said QKA fourth function value.
- 21. The method of claim 14 further comprising:
selecting a fraction of errors between said initial QKA and said initial QKB to be corrected, depending a dimension of a first code upon said fraction; and approximating a revised QKB using said first code.
- 22. The method of claim 21 further comprising applying a second code based upon a function of a word in said first code and a second code to define a final code.
- 23. The method of claim 21 wherein said fraction is greater than 11 percent.
- 24. A computer system for performing QKD, comprising:
means for determining initial QKs, initial QKA and initial QKB, initial QKA and initial QKB, each initial QK consisting of a series of information units, each information unit of each QK having one value of a set of defined values; means for performing on said initial QKA a third function to generate a QKA third function value; means for performing on said initial QKB said third function to generate a QKB third function value; wherein:
(1) said third function depends upon values of at least two bits of a QK and (2) said third function has only one of said defined values; and means for forming a revised QKA by setting a value of a bit of said revised QKA equal to said QKA third function value.
- 25. A QKD method, comprising:
computing a value X=u+QKA, wherein u is a code word in a first code, and QKA is a QK; computing a value of Y=X+QKB, where QKB is a QK; and determining to which code word in said first code the value of Y is closest.
- 26. The method of claim 25 further comprising:
selecting a fraction of errors between QKA and QKB to be corrected; depending a dimension of said first code upon said percentage; and approximating a revised QKB using said first code.
- 27. The method of claim 26 further comprising applying a second code based upon a function of a word in said first code and a second code, to define a final code.
- 28. The method of claim 26 wherein said fraction of errors between QKA and QKB is greater than 11 percent.
- 29. The method of claim 26 wherein said second code has a dual code, and wherein said first code and said second code are chosen so that said first code and said dual code correct different fractions of errors.
- 30. A system for QKD, comprising:
means for computing a value X=u+QKA, wherein u is a code word in a first code, and QKA is a QK; means for computing a value of Y=X+QKB, where QKB is a QK; and means for determining to which code word in said first code the value of Y is closest.
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority under 35 USC 119(e) to U.S. provisional application 60/287,852, filed May 1, 2001, entitled “Method and system for secure quantum key distribution using two-way classical communications.” The teachings of that application are incorporated herein by reference.
PCT Information
Filing Document |
Filing Date |
Country |
Kind |
PCT/US02/11862 |
4/30/2002 |
WO |
|