High-dimensional entanglement-based quantum key distribution

Conventional quantum key distribution (QKD) uses a discrete two-dimensional Hilbert space for key encoding, such as the polarization state of a single photon. In contrast, high-dimensional QKD allows encoding onto a larger state space, such as multiple levels of a continuous variable of a single photon, thus enabling the system to achieve higher photon information efficiency (bits/photon) and potentially higher key rate (bits/second). However, its deployment requires high-performance source, detector, and routing technologies tailored to the specific large-alphabet encoding scheme. One such high-dimensional QKD system of interest is based on time-energy entanglement, in which keys are derived from the arrival times of photon pairs generated from continuous-wave (CW) spontaneous parametric downconversion (SPDC). This thesis focuses on the implementation of a time-energy entanglement-based QKD system, with the development of several enabling technologies including an efficient single-spatial-mode source of time-energy entangled photons based on a periodically-poled KTiOPO4 (PPKTP) waveguide, GHz self-differencing InGaAs singlephoton avalanche diodes (SPADs), and the first demonstration of non-locally dispersion-canceled Franson quantum interferometry achieving 99.6% visibility. We then utilize these technologies to perform two full QKD protocols. The first protocol uses SPDCgenerated entangled photons for both key extraction and Franson interferometry, yielding a secure key rate -90 kbits/s with up to 4 bits/photon after error-correction and privacy amplification. The second protocol deploys two different photon sources: an amplified spontaneous emission (ASE) source is pulse-position modulated to perform random key generation, and a CW-SPDC source is for Franson security check. In this latter case, we have achieved a secure key rate 7.3 Mbits/s with 2.9 bits/photon, which represents the state-of-the-art in today's QKD technology.

Department dc:contributor.department

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

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2013

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/1721.1/84903

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/84903