Principal Investigators: Professor Caslav Brukner / Dr Rupert Ursin
The Project
Quantum Repeaters: Terrestrial and satellite free-space quantum communication
The subproject Quantum Repeaters focuses on a number of tools that are common and central for quantum communication over long distances.
Several key ingredients for future quantum technology are to be developed in this subproject, such as sources of entanglement, quantum channels, quantum networks and quantum memories.
Quantum communication protocols require the distribution of entanglement between separate locations with high fidelity. Transmission of quantum information is limited by decoherence and the absorption on the link. Reshaping and amplification of a quantum state is forbidden by the no-cloning theorem and so other methods must be used to ensure high fidelity transmission of quantum information. Quantum repeaters will resolve this problem by breaking quantum channels into shorter links. Entanglement distribution and purification at separate links will be used to ensure transmission of quantum information over the full channel with the required fidelity.
An independent approach to overcome the limitation in the distance for distribution of entanglement is using free-space links, involving satellites in space for bridging distances on a global scale and eventually establishing a world wide quantum communication network. A typical free space channel consists of two telescopes with a free line of sight between them. In a close collaboration between OEAW, LMU and UBRISTOL together with the European Space agency (ESA), we demonstrated the distribution of entanglement over distances of 144 km between the Canary island La Palma and Tenerife [1], which is already 30% of the distance to the international space station ISS. Free space channels are an exciting prospect because of the potential for use in conjunction with satellite technologies. In the project we will investigate the feasibility of satellite quantum communication links, including potential satellite based components and space-compatible sources of entangled photons. Potential timing, pointing and tracking problems associated with satellites will be addressed via simulations and experimental demonstrations. Objectives include measurement of single photons reflected from a low orbiting laser ranging satellite [2].
Among our goals in other subprojects (SP2.3 “Multiphoton Networks”) are the production and characterization of various multi-photon entangled states, such as GHZ, W, or Cluster states, experimental demonstration of their counter-intuitive features, and exploitation of these features for quantum information technology. Major goal is realization of one-way quantum computer based on processing of single qubits in a highly-entangled cluster state. Using this cluster state we aim to implement various quantum algorithms.
In the SP2.5 “Multi-particle and qudit entanglement purification and algorithms” we investigate entanglement between orbital angular momentum of photons, which are states of the electromagnetic field with phase singularities (doughnut modes). This opens up a practical approach to multi-dimensional entanglement where the entangled states do not only consist of two orthogonal states but of many of them. These states are expected to be of importance for the current efforts in the quantum computation and communication scheme based on higher-dimensional systems.
Figure: The setup for free-space entanglement distribution between La Palma and Tenerife. Polarisation entangled photon pairs are produced in a type-II parametric down conversion (DC) source by pumping a beta-barium-borate crystal (BBO) with a high power UV laser. One photon is measured locally on La Palma, the other one is sent through a 15 cm transceiver lens over the 144 km free-space optical link to the 1 m mirror telescope of the Optical Ground Station (OGS) on the island of Tenerife.
Other QAP Activities
- Multi-photon Networks with LMU
- Multi-particle and qudit entanglement and purification algorithms with IMPERIAL
- Quantum Channels with UG
- Advanced sources of entangled photon pairs with CNRSGRE
- Long distance fibre-optic quantum relays and purification with UNIGE
List of Publications
QAP
[1] R. Ursin, F. Tiefenbacher, T. Schmitt-Manderbach, H. Weier, T. Scheidl, M. Lindenthal, B. Blauensteiner, T. Jennewein, J. Perdigues, P. Trojek, B. Oemer, M. Fuerst, M. Meyenburg, J. Rarity, Z. Sodnik, C. Barbieri, H. Weinfurter and A. Zeilinger, Free-Space distribution of entanglement and single photons over 144 km, submitted to Nature Physics quant-ph/0607182
M. F. Andersen, C. Ryu, P. Clade et al, Quantized Rotation of Atoms From Photons with Orbital Angular Momentum, Phys. Rev. Lett. (2006) quant-ph/0607171
H. R. Böhm, S. Gigan, G. Langer et al, A high-reflective high-Q micromechanical Bragg-mirror, Appl. Phys. Lett. 89, 223101 (2006) (2006) cond-mat/0607771
J. Kofler, C. Brukner, Entanglement Distribution Revealed by macroscopic Observations, Phys. Rev. A 74 050304 (2006) quant-ph/0603208
R. Kaltenbaek, B. Blauensteiner, M. Zukowski, M. Aspelmeyer, A. Zeilinger, Experimental interference of independent photons, Phys. Rev. Lett. 96 240502 (2006) quant-ph/0603048
J. Kofler, V. Vedral, M. S. Kim, C. Brukner, Entanglement between Collective Operators in a Linear Harmonic Chain, Phys. Rev. A 73 052107 (2006) quant-ph/0506236
W. Son, C. Brukner, and M. S. Kim, Test of Nonlocality for a Continuous-Variable State Based on an Arbitrary Number of Measurement Outcomes, Phys. Rev. Lett. 97 110401 (2006) quant-ph/0602119
P. Walther, K. J. Resch, C. Brukner et al, Experimental Entangled Entanglement, Phys. Rev. Lett. 97 020501 (2006) quant-ph/0508183
P. Badziag, C. Brukner, W. Laskowski et al, Experimentally friendly geometrical criteria for entanglement, submitted to Phys. Rev. Lett. quant-ph/0711.4282
A. Fedrizzi, T. Herbst, A. Poppe et al, A wavelength-tunable fiber-coupled source of narrowband entangled photons, Optics Express 15 15377 (2007)
M. Fürst, H. Weier, T. Schmitt-Manderbach et al, Free-space quantum key distribution over 144 km, Proceedings SPIE 6399 (2006)
S. Gröblacher, S. Gigan, H. R. Boehm et al, Radiation-pressure self-cooling of a micromirror in a cryogenic environment (2007)
C. Genes, D. Vitali, P. Tombesi et al, Ground-state cooling of a micromechanical oscillator: comparing cold damping and cavity-assisted cooling schemes (2007)
H. Hübel, M. R. Vanner, T. Lederer et al, High-fidelity transmission of polarization encoded qubits from an entangled source over 100 km of fiber, Optics express 15 7853 (2007)
J. Kofler and C. Brukner, Classical world arising out of quantum physics under the restriction of coarse-grained measurements, Phys. Rev. Lett. 99 180403 (2007)
N. Kiesel, Ch. Schmid, U. Weber et al, Experimental analysis of a simple linear optics phase gate, International J. Quantum Informa 5 235 (2007)
M. Marhöfer, I. Wimberger, and A. Poppe, Applicability of quantum cryptography for securing mobile communication networks, Nova Science Publishers (2007) ISBN: 1-60021-912-8
A. Poppe, 'Quantenkryptographie: von einzelnen Photonen zum sicheren Schlüssel, Elektrotechnik & Informationstechnik 124/ 121 (2007)
R. Prevedel, M. Aspelmeyer, C. Brukner et al, Photonic Entanglement as a Resource in Quantum Information Processing, J. Opt. B 24 241 (2007)
T. Paterek, A. Fedrizzi, S. Gröblacher et al, Experimental test of non-local realistic theories without the rotational symmetry assumption, Phys. Rev. Lett. 99 210406 (2007)
A. Poppe, H. Hübel, B. Schrenk et al, Der Einsatz verschränkter Photonen für die Quantenkryptographie, Elektrotechnik & Informationstechnik 124 142 (2007)
R. Prevedel, A. Stefanov, P. Walther et al, Experimental realization of a quantum game on a one-way quantum computer, New J. Phys 9 205 (2007)
R. Prevedel, M. S. Tame, A. Stefanov et al, Experimental demonstration of decoherence-free one-way quantum processing, accepted for publication in Phys. Rev. Lett.
M. Paternostro, D. Vitali, S. Gigan et al, Creating and probing macroscopic entanglement with light, accepted for publication in Phys. Rev. Lett. quant-ph/0609210
M. Stütz, S. Gröblacher, T. Jennewein et al, How to create and detect N-dimensional entangled photons with an active phase hologram, Appl. Phys. Lett. 90 261114 (2007)
T. Schmitt-Manderbach, H, Weier, M. Fürst et al, Experimental Demonstration of Free-Space Decoy-State Quantum Key Distribution over 144 km, Phys. Rev. Lett. 98 010504 (2007)
M. S. Tame, R. Prevedel, M. Paternostro et al, Experimental Realization of Deutsch's Algorithm in a One-way Quantum Computer, Phys. Rev. Lett. 98 140501 (2007) quant-ph/0611186
R. Ursin, F. Tiefenbacher, T. Jennewein et al, Applications of quantum communication protocols in real world scenarios towards space, E&I. Electronics 5 149 (2007)
R. Ursin, F. Tiefenbacher, T. Schmitt-Manderbach et al, Entanglement based quantum communication over 144 km, Nature Phys. 3 481 (2007)
P. Walther, M. Aspelmeyer and A. Zeilinger, Heralded generation of multiphoton entanglement, Phys. Rev. A 75 12313 (2007)
P. Badziag, C. Brukner, W. Laskowski et al, Experimentally Friendly Geometrical Criteria for Entanglement, Phys. Rev. Lett. 100 140403 (2008) arXiv:0711.4282
P. Böhi, R. Prevedel, T. Jennewein et al, Implementation and characterization of active feed-forward for deterministic linear optics quantum computing, Appl. Phys. B 89 499 (2007)
I. M. Herbauts, S. Bettelli, H. Hübel et al, On the optimality of individual entangling-probe attacks against BB84 quantum key distribution, Eur. Phys. J. D 46 395 (2008)
M. Paternostro, D. Vitali, S. Gigan et al, Creating and probing macroscoping entanglement, Phys. Rev. Lett. 99 250401 (2007) quant-ph/0609210
P. Villoresi, T. Jennewein, F. Tamburini et al, Experimental verification of the feasibility of a quantum channel between Space and Earth (2008) quant-ph/0803.1871
Related work
[2] C. Bonato, M. Aspelmeyer, T. Jennewein, C. Pernechele, P. Villoresi and A. Zeilinger, Influence of satellite motion on the qubit transmission in a space-earth quantum communication link, Optics Express, Vol. 14, 10050 (2006)
M. Aspelmeyer, H. R. Boehm, A. Fedrizzi et al, Advanced Quantum Communication Experiments with Entangled Photons in "Quantum Communication and Cryptography", Quantum Communications and Cryptography, A. Sergienko (Ed.), CRC Press LLC (2005)
C. Brukner, N. Paunkovic, T. Rudolph and V. Vedral, Entanglement-assisted Orientation in Space, Int. J. of Quant. Inf 4 365 (2006) quant-ph/0509123
C. Brukner, V. Vedral and A. Zeilinger, Crucial Role of Quantum Entanglement in Bulk Properties of Solids, Phys. Rev. A 73 012110 (2006) quant-ph/0410138
C. Brukner and A. Zeilinger, Quantum Physics as a Science of Information, Springer (2005) ISBN: 3-540-22188-3
G. De Chiara, C. Brukner, R. Fazio, G. M. Palma and V. Vedral, A Scheme for Entanglement Extraction From a Solid, New J. Phys 8 95 (2006) quant-ph/0505107
A. Sen De, U. Sen, C. Brukner, V. Buzek and M. Zukowski, Entanglement Swapping of Noisy States: A Kind of Superadditivity in Nonclassicality, Phys. Rev. A 72 042310 (2005) quant-ph/0311194
S. Gröblacher, T. Jennewein, A. Vaziri, G. Weihs, A. Zeilinger, Experimental Quantum Cryptography With Qutrits, New J. Phys. 8 75 (2006) quant-ph/0511163
J. Kofler, T. Paterek and C. Brukner, Experimenter's Freedom in Bell's Theorem and Quantum Cryptography, Phys. Rev. A 73 022104 (2006)
C. Lunkes, C. Brukner and V. Vedral, Natural Multiparticle Entanglement in a Fermi Gas, Phys. Rev. Lett. 95 030503 (2005) quant-ph/0502122
C. Lunkes, C. Brukner and V. Vedral, Equation of State for Entanglement in a Fermi Gas, Phys. Rev. A 71 034309 (2005) quant-ph/0410166
K. Maruyama, C. Brukner and V. Vedral, Thermodynamical Cost of Accessing Quantum Information, J. Phys. A 38 7175-7181 (2005) quant-ph/0407151
K. J. Resch, M. Lindenthal, B. Blauensteiner et al, Distributing entanglement and single photons through an intra-city, free-space quantum channel, Opt. Express 13 202 (2006) quant-ph/0501008
K. Sanaka, K. J. Resch, A. Zeilinger, Filtering Out Photonic Fock States, Phys. Rev. Lett. 96 083601 (2006)
P. Trojek, C. Schmid, M. Bourennane et al, Experimental Quantum Communication Complexity, Phys. Rev. A 72 00305(R) (2005) quant-ph/0502066
P. Walther, M. Aspelmeyer, K. J. Resch et al, Experimental violation of a cluster state Bell inequality, Phys. Rev. Lett. 95 042325 (2005) quant-ph/0507086
P. Walther, K. J. Resch, C. Brukner et al, Quantum Nonlocality Obtained from Local States by Entanglement Purification, Phys. Rev. Lett. 94 040504 (2005) quant-ph/0502026
P. Walther, K. Resch, T. Rudolph et al, Experimental one-way quantum computing, Nature 434 169 (2005) quant-ph/0503126
M. Wiesniak, V. Vedral and C. Brukner, Magnetic Susceptibility as Macroscopic Entanglement Witness, New J. Phys. 7 258 (2005) quant-ph/0503037
A. Zeilinger, Einsteins Spuk, Bertelsmann (2006) ISBN: 3570006913
M. Aspelmeyer, Quantum Optics: Enlightened Chips, Nature 1 94 (2007)
K. J. Resch, K. L. Pregnell, R. Prevedel et al, Time-Reversal and Super-Resolving Phase Measurements, Phys. Rev. Lett. 98 223601 (2007) quant-ph/0511214
S. Gröblacher, T. Paterek, R. Kaltenbaek et al, An experimental test of non-local realism, Nature 446 871 (2007)
D. Vitali, S. Gigan, A. Ferreira et al, Optomechanical entanglement between a movable mirror and a cavity field, Phys. Rev. Lett. 98 030405 (2007) quant-ph/0609197