High performance photon-pair source based on a fiber-coupled periodically poled KTiOPO₄ waveguide

Photon-pair sources based on spontaneous parametric downconversion (SPDC) in a nonlinear crystal waveguide have been shown to be significantly more efficient than those in a bulk crystal. To utilize waveguide sources in quantum information processing (QIP) applications, it is highly desirable to integrate additional functionality such as pump sources and modulators at the waveguide-chip level for compactness, reliability, and ease of operation. As a first step we develop a waveguide SPDC source with integrated single-mode polarization-maintaining (PM) fibers in this thesis work, and demonstrate the efficient generation of photon pairs at 1316 nm in a type-II phasematched Rb-indiffused waveguide in periodically poled KTiOPO4 (PPKTP). We perform the flux and spectrum characterization of our integrated waveguide source, and obtain a pair production rate of 2 x 107/s/mW in a 1.08-nm bandwidth. The measurement results are in good agreement with a theoretical model that takes into account the transversal momentum imparted on the phase matching function by the waveguide. With narrowband filtering and a pump power, we achieve a Hong-Ou-Mandel quantum-interference visibility of 98.2% after subtraction of accidental coincidences, representing the highest reported value for a waveguide-based photon-pair source. The photon-pairs generated by our PPKTP waveguide are shown to be highly indistinguishable, in terms their spectra and spatial modes. Therefore the fiber-coupled waveguide source is particularly suitable for long-distance quantum communication protocols such as fiber-based quantum key distribution (QKD).

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2009

Author dc:creator

• Zhong, Tian, Ph. D. Massachusetts Institute of Technology

Advisor dc:contributor.advisor

• Franco N. C. Wong.

• Electrical Engineering and Computer Science.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/53325

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/53325