Ilja Gerhardt QUANTUM OPTI CQT GRO UP Ilja Gerhardt, Matthew P. Peloso, Caleb Ho, Antía Lamas-Linares and Christian Entanglement-based Free Space Quantum Cryptography in Full Daylight QUANTUM OPTIC CQT GRO UP Cen tre fo r Q u a n tu m Tech n o lo gies,Sing a p o re
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Ilja Gerhardt QUANTUM OPTICS CQT GROUP Ilja Gerhardt, Matthew P. Peloso, Caleb Ho, Antía Lamas-Linares and Christian Kurtsiefer Entanglement-based Free.
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Ilja Gerhardt
QUANTUM OPTICSCQT
GROUP
Ilja Gerhardt, Matthew P. Peloso, Caleb Ho, Antía Lamas-Linares and Christian Kurtsiefer
Entanglement-based Free Space Quantum Cryptography in Full Daylight
QUANTUM OPTICSCQT
GROUP
Centre fo rQu ant umTechn o lo g ies , Sing a p o re
Ilja Gerhardt
QUANTUM OPTICSCQT
GROUP
Introduction to QKDIntroduction to QKD
• Quantum Cryptography =Quantum Key Distribution–Have a Random Number at two
locationsOne-time pad for encryption
• 1980ies: Prepare and Send–Bennet Brassard, BB84–Send single Photons, non-cloning
theorem
• 1990ies: Entanglement Based… why?
Ilja Gerhardt
QUANTUM OPTICSCQT
GROUP
Prepare and SendPrepare and Send
• Need for Random Numbers
• Different Photons, different Colors?–Dimensionality of Hilbert space needs to
be known for security
Ilja Gerhardt
QUANTUM OPTICSCQT
GROUP
Entanglement based QKDEntanglement based QKD
• Ekert 1991 (E91)–Let’s measure two qubits of an
entangled entity–Perfect (Anti)correlation–Bell’s inequality violated= eavesdropper knowledge can be
eliminated via PA
• Photons for convenience…• Freespace: Ad-hoc set-up