The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 18, 2010
Filed:
Feb. 24, 2005
Anton Zavriyev, Swampscott, MA (US);
Harry Vig, North Billerica, MA (US);
Anton Zavriyev, Swampscott, MA (US);
Harry Vig, North Billerica, MA (US);
MagiQ Technologies, Inc, New York, NY (US);
Abstract
Methods for calibrating the modulators in a QKD system () are disclosed. The methods include setting the voltage (V) of Bob's modulator (MB) to a positive value and then adjusting the voltage (V) of Alice's modulator (MA) in both the positive and negative direction to obtain overall relative phase modulations that result in maximum and minimum photon counts (N) in the two single-photon detectors (). Bob's modulator voltage is then set to a negative value and the process repeated. When the basis voltages (V(), V(), V(), V(), V() and V()) are established, the QKD system is operated with intentionally selected incorrect bases at Bob and Alice to assess orthogonality of the basis voltages by assessing whether or not the probability of photon detection at the detectors is 50:50. If not, the modulator voltages are adjusted to be orthogonal. This involves changing Bob's basis voltage (V() and/or V()) and repeating the process until a 50:50 detector count distribution is obtained. The calibration method can be carried out periodically during QKD system operation to ensure optimum or near-optimum operation of the modulators.