liu.seSearch for publications in DiVA
Change search
ReferencesLink to record
Permanent link

Direct link
A Classical-Light Attack on Energy-Time Entangled Quantum Key Distribution, and Countermeasures
Linköping University, Department of Electrical Engineering, Information Coding. Linköping University, The Institute of Technology.ORCID iD: 0000-0002-8032-1466
2015 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Quantum key distribution (QKD) is an application of quantum mechanics that allowstwo parties to communicate with perfect secrecy. Traditional QKD uses polarization of individual photons, but the development of energy-time entanglement could lead to QKD protocols robust against environmental effects. The security proofs of energy-time entangled QKD rely on a violation of the Bell inequality to certify the system as secure. This thesis shows that the Bell violation can be faked in energy-time entangled QKD protocols that involve a postselection step, such as Franson-based setups. Using pulsed and phase-modulated classical light, it is possible to circumvent the Bell test which allows for a local hidden-variable model to give the same predictions as the quantum-mechanical description. We show that this attack works experimentally and also how energy-time-entangled systems can be strengthened to avoid our attack.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2015. , 60 p.
Linköping Studies in Science and Technology. Thesis, ISSN 0280-7971 ; 1709
Keyword [en]
Quantum Key Distribution, Energy-Time Entanglement, Quantum Information
Keyword [sv]
Kvantkryptering, Energi-Tid-Snärjning, Kvantinformation
National Category
Other Physics Topics
URN: urn:nbn:se:liu:diva-114073DOI: 10.3384/lic.diva-114073ISBN: 978-91-7519-118-8 (print)OAI: diva2:786875
2015-02-27, Visionen, B-huset, Campus Valla, Linköpings Universitet, Linköping, 13:15 (English)
Available from: 2015-02-18 Created: 2015-02-06 Last updated: 2015-02-18Bibliographically approved
List of papers
1. Energy-time entanglement, elements of reality, and local realism
Open this publication in new window or tab >>Energy-time entanglement, elements of reality, and local realism
2014 (English)In: Journal of Physics A: Mathematical and Theoretical, ISSN 1751-8113, E-ISSN 1751-8121, Vol. 47, no 42, 424032- p.Article in journal (Refereed) Published
Abstract [en]

The Franson interferometer, proposed in 1989 (Franson 1989 Phys. Rev. Lett. 62 2205-08), beautifully shows the counter-intuitive nature of light. The quantum description predicts sinusoidal interference for specific outcomes of the experiment, and these predictions can be verified in experiment. In the spirit of Einstein, Podolsky, and Rosen it is possible to ask if the quantum-mechanical description (of this setup) can be considered complete. This question will be answered in detail in this paper, by delineating the quite complicated relation between energy-time entanglement experiments and Einstein-Podolsky-Rosen (EPR) elements of reality. The mentioned sinusoidal interference pattern is the same as that giving a violation in the usual Bell experiment. Even so, depending on the precise requirements made on the local realist model, this can imply (a) no violation, (b) smaller violation than usual, or (c) full violation of the appropriate statistical bound. Alternatives include (a) using only the measurement outcomes as EPR elements of reality, (b) using the emission time as EPR element of reality, (c) using path realism, or (d) using a modified setup. This paper discusses the nature of these alternatives and how to choose between them. The subtleties of this discussion needs to be taken into account when designing and setting up experiments intended to test local realism. Furthermore, these considerations are also important for quantum communication, for example in Bell-inequality-based quantum cryptography, especially when aiming for device independence.

Place, publisher, year, edition, pages
IOP Publishing: Hybrid Open Access, 2014
bell inequalities; energy-time entanglement; elements of reality
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
urn:nbn:se:liu:diva-112643 (URN)10.1088/1751-8113/47/42/424032 (DOI)000344222200033 ()
Available from: 2014-12-05 Created: 2014-12-05 Last updated: 2016-08-31
2. Hacking energy-time entanglement-based systems with classical light
Open this publication in new window or tab >>Hacking energy-time entanglement-based systems with classical light
Show others...
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Photonic systems based on energy-time entanglement have been proposed to test local realism using the Bell inequality. A violation of this inequality normally also certifies security of device-independent quantum key distribution, so that an attacker cannot eavesdrop or control the system. Here, we show how this security test can be circumvented in energy-time entangled systems when using standard avalanche photodetectors, allowing an attacker to compromise the system without leaving a trace. With tailored pulses of classical light we reach Bell values up to 3.63 at 97.6% detector efficiency which is an extreme violation. This is the first demonstration of a violation-faking source that both gives tunable violation and high detector efficiency. The implications are severe: the standard Clauser-Horne-Shimony-Holt inequality cannot be used to show device-independent security for standard postselecting energy-time entanglement setups. We conclude with suggestions of improved tests and experimental setups that can re-establish device-independent security.

National Category
Electrical Engineering, Electronic Engineering, Information Engineering
urn:nbn:se:liu:diva-114210 (URN)
Available from: 2015-02-13 Created: 2015-02-13 Last updated: 2015-02-18Bibliographically approved

Open Access in DiVA

Classical-Light Attack on Energy-Time Entangled Quantum Key Distribution, and Countermeasures(562 kB)374 downloads
File information
File name FULLTEXT03.pdfFile size 562 kBChecksum SHA-512
Type fulltextMimetype application/pdf
omslag(91 kB)7 downloads
File information
File name COVER01.pdfFile size 91 kBChecksum SHA-512
Type coverMimetype application/pdf

Other links

Publisher's full text

Search in DiVA

By author/editor
Jogenfors, Jonathan
By organisation
Information CodingThe Institute of Technology
Other Physics Topics

Search outside of DiVA

GoogleGoogle Scholar
Total: 376 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 1277 hits
ReferencesLink to record
Permanent link

Direct link