The black paper of quantum cryptography: real implementation problems (2009)
Scarani, Valerio, Kurtsiefer, Christian
The fact that the laws of physics play a role in the security of quantum key distribution (QKD) has often been misunderstood, as if the security of QKD would be based \textit{only} of the laws of...
Updating Quantum Cryptography Report ver. 1 (2009)
Dodson, Donna, Fujiwara, Mikio, Grangier, Philippe, Hayashi, Masahito, Imafuku, Kentaro, Kitayama, Ken-ichi, ...
Quantum cryptographic technology (QCT) is expected to be a fundamental technology for realizing long-term information security even against as-yet-unknown future technologies. More advanced security...
Eliminating Spectral Distinguishability in Ultrafast Spontaneous Parametric Down-conversion (2009)
Poh, Hou Shun, Lim, Jiaqing, Marcikic, Ivan, Lamas-Linares, Antia, Kurtsiefer, Christian
Generation of polarization-entangled photon pairs with a precise timing through down-conversion of femtosecond pulses is often faced with a degraded polarization entanglement quality. In a previous...
Phase shift of a weak coherent beam induced by a single atom (2009)
Aljunid, Syed Abdullah, Tey, Meng Khoon, Chng, Brenda, Liew, Timothy, Maslennikov, Gleb, Scarani, Valerio, ...
We report on a direct measurement of a phase shift on a weak coherent beam by a single Rb-87 atom in a Mach-Zehnder interferometer. A maximum phase shift of about 1 degree is observed experimentally.
Clock synchronization by remote detection of correlated photon pairs (2009)
Ho, Caleb, Lamas-Linares, Antia, Kurtsiefer, Christian
We present an algorithm to detect the time and frequency difference of independent clocks based on observation of time-correlated photon pairs. This enables remote coincidence identification in...
Daylight operation of a free space, entanglement-based quantum key distribution system (2008)
Peloso, Matthew P., Gerhardt, Ilja, Ho, Caleb, Lamas-Linares, Antia, Kurtsiefer, Christian
Many quantum key distribution (QKD) implementations using a free space transmission path are restricted to operation at night time in order to distinguish the signal photons used for a secure key...
Gaertner, Sascha, Bourennane, Mohamed, Kurtsiefer, Christian, Cabello, Adan, Weinfurter, Harald
Gao et al. [Phys. Rev. Lett. 101, 208901 (2008)] have described a possible intercept-resend attack for the quantum protocol for detectable Byzantine agreement in Phys. Rev. Lett. 100, 070504 (2008)....
Accuracy of minimal and optimal qubit tomography for finite-length experiments (2008)
Ling, Alex, Lamas-Linares, Antia, Kurtsiefer, Christian
Practical quantum state tomography is usually performed by carrying out repeated measurements on many copies of a given state. The accuracy of the reconstruction depends strongly on the...
Experimental quantum key distribution based on a Bell test (2008)
Ling, Alexander, Peloso, Matthew P., Marcikic, Ivan, Scarani, Valerio, Lamas-Linares, Antia, Kurtsiefer, Christian
We report on a complete free-space field implementation of a modified Ekert91 protocol for quantum key distribution using entangled photon pairs. For each photon pair we perform a random choice...
Interfacing light and single atoms with a lens (2008)
Tey, Meng Khoon, Maslennikov, Gleb, Liew, Timothy C. H., Aljunid, Syed Abdullah, Huber, Florian, Chng, Brenda, ...
We characterize the interaction between a single atom or similar microscopic system and a light field via the scattering ratio. For that, we first derive the electrical field in a strongly focused...
Sagnac-loop phase shifter with polarization-independent operation (2008)
Ng, Tien Tjuen, Gosal, Darwin, Lamas-Linares, Antia, Kurtsiefer, Christian
A bulk-optics, polarization-independent phase shifter for photonic quantum information applications is demonstrated. A transverse mode electro-optic modulator using lithium niobate is placed in a...
Deliverable D (report, Christian Kurtsiefer, Harald Weinfurter, Hugues De Riedmatten, Wolfgang Tittel, Hugo Zbinden, ...
This report summarises the ongoing work in QuComm on fiber based entanglement quantum cryptography. Report Version: 1 Report Preparation Date: 2002-01-05 Classification: Internal Project funded by...
Strong interaction between light and a single trapped atom without a cavity (2008)
Tey, Meng Khoon, Chen, Zilong, Aljunid, Syed Abdullah, Chng, Brenda, Huber, Florian, Maslennikov, Gleb, ...
Coupling of light to an atom at single quanta level with high probability is a building block for many quantum information processing protocols. It is commonly believed that efficient coupling is...
Ling, Alexander, Lamas-Linares, Antia, Kurtsiefer, Christian
We provide an estimate on the absolute values of the emission rate of photon pairs produced by spontaneous parametric down conversion in a bulk crystal when all interacting fields are in single...
A simple approach to test Leggett's model of nonlocal quantum correlations (2008)
Branciard, Cyril, Brunner, Nicolas, Gisin, Nicolas, Kurtsiefer, Christian, Lamas-Linares, Antia, Ling, Alexander, ...
We present new inequalities for testing Leggett's model [Found. Phys. 33, 1469 (2003)] of non-local quantum correlations. Remarkably these inequalities can be derived in a very simple way, assuming...
Experimental Demonstration of a Quantum Protocol for Byzantine Agreement and Liar Detection (2008)
Gaertner, Sascha, Bourennane, Mohamed, Kurtsiefer, Christian, Cabello, Adán, Weinfurter, Harald
Experimental demonstration of a quantum protocol for Byzantine agreement and liar detection (2007)
Gaertner, Sascha, Bourennane, Mohamed, Kurtsiefer, Christian, Cabello, Adan, Weinfurter, Harald
We introduce a new quantum protocol for solving detectable Byzantine agreement (also called detectable broadcast) between three parties, and also for solving the detectable liar detection problem....
Experimental Falsification of Leggett's Non-Local Variable Model (2007)
Branciard, Cyril, Ling, Alexander, Gisin, Nicolas, Kurtsiefer, Christian, Lamas-Linares, Antia, Scarani, Valerio
Bell's theorem guarantees that no model based on local variables can reproduce quantum correlations. Also some models based on non-local variables, if subject to apparently "reasonable" constraints,...
Breaking a quantum key distribution system through a timing side channel (2007)
Lamas-Linares, Antia, Kurtsiefer, Christian
The security of quantum key distribution relies on the validity of quantum mechanics as a description of nature and on the non-existence of leaky degrees of freedom in the practical implementations....
Experimental Demonstration of Free-Space Decoy-State Quantum Key Distribution over 144 km (2007)
Schmitt-Manderbach, Tobias, Weier, Henning, Fürst, Martin, Ursin, Rupert, Tiefenbacher, Felix, Scheidel, Thomas, ...
Reply to Comment on 'Experimental single Qubit Quantum Secret Sharing' (2007)
Schmid, Christian, Trojek, Pavel, Bourennane, Mohamed, Kurtsiefer, Christian, Zukowski, Marek, Weinfurter, Harald
Experimental Demonstration of Four-Party Quantum Secret Sharing (2007)
Gaertner, Sascha, Kurtsiefer, Christian, Bourennane, Mohamed, Weinfurter, Harald
Joint Spectrum Mapping of Polarization Entanglement in Spontaneous Parametric Down-conversion (2006)
Poh, Hou Shun, Lum, Chune Yang, Marcikic, Ivan, Lamas-Linares, Antia, Kurtsiefer, Christian
Polarization-entangled photon pairs can be efficiently prepared into pure Bell states with a high fidelity via type-II spontaneous parametric down-conversion (SPDC) of narrow-band pump light....
Free-space quantum key distribution with entangled photons (2006)
Marcikic, Ivan, Lamas-Linares, Antia, Kurtsiefer, Christian
We report on a complete experimental implementation of a quantum key distribution protocol through a free space link using polarization-entangled photon pairs from a compact parametric...
Entanglement Persistency of Multiphoton Entangled States (2006)
Bourennane,Mohamed, Eibl,Manfred, Gaertner,Sascha, Kiesel,Nikolai, Kurtsiefer,Christian, Weinfurter,Harald
Experimental Polarization State Tomography using Optimal Polarimeters (2006)
Ling, Alexander, Pang, Soh Kee, Lamas-Linares, Antia, Kurtsiefer, Christian
We report on the experimental implementation of a polarimeter based on a scheme known to be optimal for obtaining the polarization vector of ensembles of spin-1/2 quantum systems, and the alignment...
Observation of Entanglement of a Single Photon with a Trapped Atom (2006)
Volz,Jürgen, Weber,Markus, Schlenk,Daniel, Rosenfeld,Wenjamin, Saucke,Karen, Kurtsiefer,Christian, ...
Single photon emission from SiV centres in diamond produced by ion implantation (2006)
Wang,Chunlang, Kurtsiefer,Christian, Weinfurter,Harald, Burchard,Bernd
Single photon emission from SiV centres in diamond produced by ion implantation (2006)
Wang, Chunlang, Kurtsiefer, Christian, Weinfurter, Harald, Burchard, Bernd
Observation of Entanglement of a Single Photon with a Trapped Atom (2006)
Volz, Jürgen, Weber, Markus, Schlenk, Daniel, Rosenfeld, Wenjamin, Saucke, Karen, Kurtsiefer, Christian, ...
Entanglement Persistency of Multiphoton Entangled States (2006)
Bourennane, Mohamed, Eibl, Manfred, Gaertner, Sascha, Kiesel, Nikolai, Kurtsiefer, Christian, Weinfurter, Harald
Analysis of a single-atom dipole trap (2006)
Weber, Markus, Volz, Jürgen, Saucke, Karen, Kurtsiefer, Christian, Weinfurter, Harald
Complete Deterministic Linear Optics Bell State Analysis (2006)
Schuck, Carsten, Huber, Gerhard, Kurtsiefer, Christian, Weinfurter, Harald
Experimental quantum secret sharing (2006)
Schmid, Christian, Trojek, Pavel, Gaertner, Sascha, Bourennane, M., Kurtsiefer, Christian, Zukowski, M., ...
Free space quantum key distribution: Towards a real life application (2006)
Weier, Henning, Schmitt-Manderbach, Tobias, Regner, Nadja, Kurtsiefer, Christian, Weinfurter, Harald
Experimental Single Qubit Quantum Secret Sharing (2005)
Schmid,Christian, Trojek,Pavel, Bourennane,Mohamed, Kurtsiefer,Christian, Żukowski,Marek, Weinfurter,Harald
Analysis of a single-atom dipole trap (2005)
Weber, Markus, Volz, Juergen, Saucke, Karen, Kurtsiefer, Christian, Weinfurter, Harald
We describe a simple experimental technique which allows to store a single Rubidium 87 atom in an optical dipole trap. Due to light-induced two-body collisions during the loading stage of the trap...
Atom-Photon Entanglement (2005)
Volz, Juergen, Weber, Markus, Schlenk, Daniel, Rosenfeld, Wenjamin, Vrana, Johannes, Saucke, Karen, ...
We report the observation of entanglement between a single trapped atom and a single photon at a wavelength suitable for low-loss communication over large distances, thereby achieving a crucial step...
An Optimal Photon Counting Polarimeter (2005)
Ling, Alexander, Pang, Soh Kee, Lamas-Linares, Antia, Kurtsiefer, Christian
We present experimental results on a method to perform polarimetry on ensembles of single photons. Our setup is based on a measurement method known to be optimal for estimating the state of two level...
Single Qubit Quantum Secret Sharing (2005)
Schmid, Christian, Trojek, Pavel, Weinfurter, Harald, Bourennane, Mohamed, Zukowski, Marek, Kurtsiefer, Christian
We present a simple and practical protocol for the solution of a secure multiparty communication task, the secret sharing, and its experimental realization. In this protocol, a secret message is...
Experimental Single Qubit Quantum Secret Sharing (2005)
Schmid, Christian, Trojek, Pavel, Bourennane, Mohamed, Kurtsiefer, Christian, Żukowski, Marek, Weinfurter, Harald
Decoherence-free quantum information processing with four-photon entangled states (2004)
Bourennane,Mohamed, Eibl,Manfred, Gaertner,Sascha, Kurtsiefer,Christian, Cabello,Adán, Weinfurter,Harald
Four photon polarization entanglement tests and applications (2004)
Bourennane,Mohamed, Eibl,Manfred, Gaertner,Sascha, Kurtsiefer,Christian, Weinfurter,Harald, Cabello,A., ...
Experimental realization of a three-qubit entangled W state (2004)
Eibl,Manfred, Kiesel,Nikolai, Bourennane,Mohamed, Kurtsiefer,Christian, Weinfurter,Harald
Decoherence-free quantum information processing with four-photon entangled states (2004)
Bourennane, Mohamed, Eibl, Manfred, Gaertner, Sascha, Kurtsiefer, Christian, Cabello, Adán, Weinfurter, Harald
Experimental realization of a three-qubit entangled W state (2004)
Eibl, Manfred, Kiesel, Nikolai, Bourennane, Mohamed, Kurtsiefer, Christian, Weinfurter, Harald
Four photon polarization entanglement tests and applications (2004)
Bourennane, Mohamed, Eibl, Manfred, Gaertner, Sascha, Kurtsiefer, Christian, Weinfurter, Harald, Cabello, A., ...
Decoherence-Free Quantum Information Processing with Four-Photon Entangled States (2003)
Bourennane, Mohamed, Eibl, Manfred, Gaertner, Sascha, Kurtsiefer, Christian, Cabello, Adan, Weinfurter, Harald
Decoherence-free states protect quantum information from collective noise, the predominant cause of decoherence in current implementations of quantum communication and computation. Here we...
Witnessing multipartite entanglement (2003)
Bourennane, Mohamed, Eibl, Manfred, Kurtsiefer, Christian, Gaertner, Sascha, Weinfurter, Harald, Guehne, Otfried, ...
We present the experimental detection of genuine multipartite entanglement using entanglement witness operators. To this aim we introduce a canonical way of constructing and decomposing witness...
Mulitphoton Entanglement (2003)
Bourennane,Mohamed, Eibl,Manfred, Gaertner,Sascha, Kiesel,Nikolai, Kurtsiefer,Christian, Zukowski,Marek, ...
Multiphoton entanglement and interferometry (2003)
Bourennane,Mohamed, Eibl,Manfred, Gaertner,Sascha, Kiesel,Nikolai, Kurtsiefer,Christian, Zukowski,M., ...
Mulitphoton Entanglement (2003)
Bourennane, Mohamed, Eibl, Manfred, Gaertner, Sascha, Kiesel, Nikolai, Kurtsiefer, Christian, Zukowski, Marek, ...
Multiphoton entanglement and interferometry (2003)
Bourennane, Mohamed, Eibl, Manfred, Gaertner, Sascha, Kiesel, Nikolai, Kurtsiefer, Christian, Zukowski, M., ...
Eibl, Manfred, Kiesel, Nikolai, Bourennane, Mohamed, Gaertner, Sascha, Kurtsiefer, Christian, Weinfurter, Harald
Ascertaining the Values of $\sigma_x$, $\sigma_y$, and $\sigma_z$ of a Polarization Qubit (2002)
Schulz, Oliver, Steinhübl, Ruprecht, Weber, Markus, Englert, Berthold-Georg, Kurtsiefer, Christian, Weinfurter, Harald
In the 1987 spin retrodiction puzzle of Vaidman, Aharonov, and Albert one is challenged to ascertain the values of $\sigma_x$, $\sigma_y$, and $\sigma_z$ of a spin-1/2 particle by utilizing...
Secure communication with single-photon two-qubit states (2002)
Beige,Almut, Englert,Berthold-Georg, Kurtsiefer,Christian, Weinfurter,Harald
We propose a cryptographic scheme that is deterministic: Alice sends single photons to Bob, and each and every photon detected supplies one key bit-no photon is wasted. This is in marked contrast to...
Secure communication with a publicly known key (2002)
Beige,Almut, Englert,Berthold-Georg, Kurtsiefer,Christian, Weinfurter,Harald
We present a scheme for direct and confidential communication between Alice and Bob, where there is no need for establishing a shared secret key first, and where the key used by Alice even will...
Communicating with Qubit Pairs (2002)
Beige,Almut, Englert,Berthold-Georg, Kurtsiefer,Christian, Weinfurter,Harald
Long-distance free-space quantum cryptography (2002)
Kurtsiefer,Christian, Zarda,P., Halder,M., Gorman,Ph. M., Tapster,Paul R., Rarity,J. G., ...
Multiphoton Entanglement (2002)
Bourennane,Mohamed, Eibl,Manfred, Gaertner,Sascha, Kiesel,Nikolai, Kurtsiefer,Christian, Weinfurter,Harald
Secure communication with a publicly known key (2002)
Beige, Almut, Englert, Berthold-Georg, Kurtsiefer, Christian, Weinfurter, Harald
We present a scheme for direct and confidential communication between Alice and Bob, where there is no need for establishing a shared secret key first, and where the key used by Alice even will...
Secure communication with single-photon two-qubit states (2002)
Beige, Almut, Englert, Berthold-Georg, Kurtsiefer, Christian, Weinfurter, Harald
We propose a cryptographic scheme that is deterministic: Alice sends single photons to Bob, and each and every photon detected supplies one key bit-no photon is wasted. This is in marked contrast to...
Communicating with Qubit Pairs (2002)
Beige, Almut, Englert, Berthold-Georg, Kurtsiefer, Christian, Weinfurter, Harald
Long-distance free-space quantum cryptography (2002)
Kurtsiefer, Christian, Zarda, P., Halder, M., Gorman, Ph. M., Tapster, Paul R., Rarity, J. G., ...
Multiphoton Entanglement (2002)
Bourennane, Mohamed, Eibl, Manfred, Gaertner, Sascha, Kiesel, Nikolai, Kurtsiefer, Christian, Weinfurter, Harald
Secure communication with a publicly known key (2001)
Beige, Almut, Englert, Berthold-Georg, Kurtsiefer, Christian, Weinfurter, Harald
We present a scheme for direct and confidential communication between Alice and Bob, where there is no need for establishing a shared secret key first, and where the key used by Alice even will...
The breakdown flash of Silicon Avalance Photodiodes - backdoor for eavesdropper attacks? (2001)
Kurtsiefer, Christian, Zarda, Patrick, Mayer, Sonja, Weinfurter, Harald
Silicon avalanche photodiodes are the most sensitive photodetectors in the visible to near infrared region. However, when they are used for single photon detection in a Geiger mode, they are known to...
Universal unitary gate for single-photon 2-qubit states (2001)
Englert, Berthold-Georg, Kurtsiefer, Christian, Weinfurter, Harald
Upon entangling a spatial binary alternative of a photon with its polarization, one can use single photons to study arbitrary 2-qubit states. Sending the photon through a Mach-Zehnder interferometer,...
Secure communication with single-photon two-qubit states (2001)
Beige, Almut, Englert, Berthold-Georg, Kurtsiefer, Christian, Weinfurter, Harald
We propose a cryptographic scheme that is deterministic: Alice sends single photons to Bob, and each and every photon detected supplies one key bit -- no photon is wasted. This is in marked contrast...
High efficiency entangled photon pair collection in type II parametric fluorescence (2001)
Kurtsiefer, Christian, Oberparleiter, Markus, Weinfurter, Harald
We report on a method for optimizing the collection of entangled photon pairs in type-II parametric fluorescence. With this technique, we detected 360000 polarization-entangled photon pairs per...
Zugl.: Konstanz, Universiẗat, Diss., 1997.
Diffraction of atoms from optical potentials (1994)
Pfau, Tilman, Schnetz, Andreas, Adams, Charles S., Kurtsiefer, Christian, Sigel, Martin, Mlynek, Jürgen
In the first part of this article we attempt to provide a very brief introduction to atom optics. In the second part we report on a recent experiment in our group on an atom-optical element that may...
Loss of spatial coherence by a single spontaneous emission (1994)
Pfau, Tilman, Spälter, Stefan, Kurtsiefer, Christian, Ekstrom, Christopher R., Mlynek, Jürgen
We have demonstrated the loss of transverse spatial coherence of an atomic wave function after a single spontaneous emission. He* atoms were both diffracted and excited by a standing light wave with...
Interactions of atoms with a magneto-optical potential (1993)
Adams, Charles S., Pfau, Tilman, Kurtsiefer, Christian, Mlynek, Jürgen
A theoretical study of the coherent interaction of multilevel atoms with a magneto-optical potential is presented. The potential is formed by counterpropagating linearly polarized laser beams whose...
Magneto-optical beam splitter for atoms (1993)
Pfau, Tilman, Kurtsiefer, Christian, Adams, Charles S., Sigel, Martin, Mlynek, Jürgen
We report an experimental demonstration of diffraction of He* atoms from a magneto-optical grating. The grating was produced by the interaction of three-level atoms with a light field of spatially...
Optical elements for atoms : a beamsplitter and a mirror (1993)
Sigel, Martin, Pfau, Tilman, Adams, Charles S., Kurtsiefer, Christian, Seifert, Werner, Heine, Claus, ...
In the first part of this article we attempt to provide a very brief introduction to atom optics. In the second and third part we report on recent experiments in our group on two specific...