Hannover 2016 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 62: Quantum Information: Quantum Computing and Communication III

Q 62.4: Vortrag

Freitag, 4. März 2016, 11:45–12:00, e214

Towards practical device-independent quantum key distribution with spontaneous parametric downconversion sources, on-off photodetectors and entanglement swapping — •Kaushik Seshadreesan^{1, 2}, Masahiro Takeoka², and Masahide Sasaki² — ¹Max Planck Institute for the Science of Light, Guenther-Scharowsky-Str. 1/Bldg. 24, D-91058 Erlangen, Germany — ²National Institute of Information and Communications Technology, Koganei, Tokyo 184-8795, Japan

Device-independent quantum key distribution (DIQKD) guarantees unconditional security of secret key without making assumptions about the internal workings of the devices used. The security of DIQKD relies on the verification of nonlocal correlations via the violation of a Bell’s inequality in a loophole-free test. The primary challenge in realizing DIQKD in practice is the detection loophole problem associated with optical tests of Bell’s inequalities over long distances. We revisit a proposal [1] to use a linear optics-based entanglement swapping relay to counter this problem by considering realistic models for the entanglement sources and photodetectors. More precisely, we consider (a) polarization-entangled states based on a pair of pulsed SPDCs that have infinitely higher order multiphoton components and multimode spectral structure, and (b) on-off photodetectors that have non-unit efficiencies and non-zero dark count probabilities. Our results show that the imperfect entanglement swapping relay-based scheme can still enable positive secret key rates at distances of about a 100 kilometers.

[1] Curty and Moroder, Phys. Rev. A 84, 010304(R) (2011).