Bialczak, Radoslaw C., Ansmann, Markus, Hofheinz, Max, Lucero, Erik, Neeley, Matthew, O'Connell, Aaron, ...
Quantum logic gates must perform properly when operating on their standard input basis states, as well as when operating on complex superpositions of these states. Experiments using superconducting...
3 Habitable Zones in Extrasolar Planetary Systems (2009)
Siegfried Franck, Werner Von Bloh, Christine Bounama, Matthias Steffen, Detlef Schönberner, Hans-joachim Schellnhuber
If we ask the question about the possible existence of the life outside the Earth, we first have to determine the habitable zone (HZ) for our solar system. The HZ of distances between a main sequence...
Determination of habitable zones in extrasolar planetary systems: Where are Gaia’s sisters (2009)
Siegfried Franck, Werner Von Bloh, Christine Bounama, Matthias Steffen, Detlef Schönberner, Hans-joachim Schellnhuber
A general modeling scheme for assessing the suitability for life of extrasolar planets is presented. The scheme focuses on the identification of the “habitable zone ” in main-sequence star...
Matthias Steffen, Lieven M. K, Isaac L. Chuang
The unceasing miniaturization of semiconductor integrated circuits is widely expected to end within the next 20 years due to the fundamental impossibility of patterning features smaller than the...
Matthias Steffen, Lieven M. K, Isaac L. Chuang
The unceasing miniaturization of semiconductor integrated circuits is widely expected to end within the next 20 years due to the fundamental impossibility of patterning features smaller than the...
Overview of the lithium problem in metal-poor stars and new results on 6Li (2008)
Cayrel, Roger, Steffen, Matthias, Bonifacio, Piercarlo, Ludwig, Hans-Günter, Caffau, Elisabetta
Two problems are discussed here. The first one is the 0.4 dex discrepancy between the 7Li abundance derived from the spectra of metal-poor halo stars on the one hand, and from Big Bang...
Overview of the lithium problem in metal-poor stars and new results on 6Li (2008)
Cayrel, Roger, Steffen, Matthias, Bonifacio, Piercarlo, Ludwig, Hans-Günter, Caffau, Elisabetta
Two problems are discussed here. The first one is the 0.4 dex discrepancy between the 7Li abundance derived from the spectra of metal-poor halo stars on the one hand, and from Big Bang...
Overview of the lithium problem in metal-poor stars and new results on 6Li (2008)
Cayrel, Roger, Steffen, Matthias, Bonifacio, Piercarlo, Ludwig, Hans-Günter, Caffau, Elisabetta
Two problems are discussed here. The first one is the 0.4 dex discrepancy between the 7Li abundance derived from the spectra of metal-poor halo stars on the one hand, and from Big Bang...
Decoherence of floating qubits due to capacitive coupling (2008)
Steffen, Matthias, Brito, Frederico, DiVincenzo, David, Kumar, Shwetank, Ketchen, Mark
It has often been assumed that electrically floating qubits, such as flux qubits, are immune to decoherence due to capacitive coupling. We show that capacitive coupling to bias leads can be a...
Fault-Tolerant Computing With Biased-Noise Superconducting Qubits (2008)
Aliferis, Panos, Brito, Frederico, DiVincenzo, David P., Preskill, John, Steffen, Matthias, Terhal, Barbara M.
We present a universal scheme of pulsed operations for the IBM oscillator-stabilized flux qubit comprising the CPHASE gate, single-qubit preparations and measurements. Based on numerical simulations,...
Caffau, Elisabetta, Ludwig, Hans-G., Steffen, Matthias, Ayres, Thomas R., Bonifacio, Piercarlo, Cayrel, Roger, ...
The solar oxygen abundance has undergone a major downward revision in the last decade, the most noticeable one being the update including 3D hydrodynamical simulations to model the solar photosphere....
Sandin, Christer, Schönberner, Detlef, Roth, Martin M., Steffen, Matthias, Böhm, Petra, Monreal-Ibero, Ana
Strong mass loss off stars at the tip of the asymptotic giant branch (AGB) profoundly affects properties of these stars and their surroundings, including the subsequent planetary nebula (PN) stage....
Caffau, Elisabetta, Ludwig, Hans-G., Steffen, Matthias, R. Ayres, Thomas, Bonifacio, Piercarlo, Cayrel, Roger, ...
The solar oxygen abundance has undergone a major downward revision in the last decade, the most noticeable one being the update including 3D hydrodynamical simulations to model the solar photosphere....
Caffau, Elisabetta, Ludwig, Hans-G., Steffen, Matthias, R. Ayres, Thomas, Bonifacio, Piercarlo, Cayrel, Roger, ...
The solar oxygen abundance has undergone a major downward revision in the last decade, the most noticeable one being the update including 3D hydrodynamical simulations to model the solar photosphere....
Overview of the lithium problem in metal-poor stars and new results on 6Li (2008)
Cayrel, Roger, Steffen, Matthias, Bonifacio, Piercarlo, Ludwig, Hans-Günter, Caffau, Elisabetta
Two problems are discussed here. The first one is the 0.4 dex discrepancy between the 7Li abundance derived from the spectra of metal-poor halo stars on the one hand, and from Big Bang...
Overview of the lithium problem in metal-poor stars and new results on 6Li (2008)
Cayrel, Roger, Steffen, Matthias, Bonifacio, Piercarlo, Ludwig, Hans-Günter, Caffau, Elisabetta
Two problems are discussed here. The first one is the 0.4 dex discrepancy between the 7Li abundance derived from the spectra of metal-poor halo stars on the one hand, and from Big Bang...
Determination of habitable zones in extrasolar planetary systems: Where are Gaia’s sisters? (2007)
Siegfried Franck, Werner Von Bloh, Christine Bounama, Matthias Steffen, Detlef Schönberner, Hans-joachim Schellnhuber
Abstract. A general modeling scheme for assessing the suitability for life of extrasolar planets is presented. The scheme focuses on the identification of the “habitable zone ” in main sequence...
on Simultaneous Soft Pulses Applied at Nearby Frequencies (2007)
Matthias Steffen, Isaac L. Chuang
The rotation of a spin subject to an on-resonance soft pulse and simultaneously to a soft pulse at a nearby frequency may strongly deviate from the desired rotation expected for a single on-resonance...
Efficient one- and two-qubit pulsed gates for an oscillator stabilized Josephson qubit (2007)
Brito, Frederico, DiVincenzo, David P., Koch, Roger H., Steffen, Matthias
We present theoretical schemes for performing high-fidelity one- and two-qubit pulsed gates for a superconducting flux qubit. The "IBM qubit" consists of three Josephson junctions, three loops, and a...
Line shift, line asymmetry, and the 6Li/7Li isotopic ratio determination (2007)
Cayrel, Roger, Steffen, Matthias, Chand, Hum, Bonifacio, Piercarlo, Spite, Monique, Spite, François, ...
Context: Line asymmetries are generated by convective Doppler shifts in stellar atmospheres, especially in metal-poor stars, where convective motions penetrate to higher atmospheric levels. Such...
The solar photospheric abundance of phosphorus: results from co5bold 3D model atmospheres (2007)
Caffau, Elisabetta, Steffen, Matthias, Sbordone, Luca, Ludwig, Hans-G., Bonifacio, Piercarlo
aims: We determine the solar abundance of phosphorus using co5bold 3D hydrodynamic model atmospheres. method: High resolution, high signal-to-noise solar spectra of the PI lines of Multiplet 1 at...
Sulphur abundances from the SI near-infrared triplet at 1045 nm (2007)
Caffau, Elisabetta, Faraggiana, Rosanna, Bonifacio, Piercarlo, Ludwig, Hans-G., Steffen, Matthias
context : Unlike silicon and calcium, sulphur is an alpha-element which does not form dust. Some of the available observations of the evolution of sulphur with metallicity indicate an increased...
Hydrodynamical model atmospheres and 3D spectral synthesis (2007)
Ludwig, Hans-G., Steffen, Matthias
We discuss three issues in the context of three-dimensional (3D) hydrodynamical model atmospheres for late-type stars, related to spectral line shifts, radiative transfer in metal-poor 3D models, and...
Sulphur abundances from the SI near-infrared triplet at 1045 nm (2007)
Caffau, Elisabetta, Faraggiana, Rosanna, Bonifacio, Piercarlo, Ludwig, Hans-G., Steffen, Matthias
context : Unlike silicon and calcium, sulphur is an alpha-element which does not form dust. Some of the available observations of the evolution of sulphur with metallicity indicate an increased...
The solar photospheric abundance of phosphorus: results from co5bold 3D model atmospheres (2007)
Caffau, Elisabetta, Steffen, Matthias, Sbordone, Luca, Ludwig, Hans-G., Bonifacio, Piercarlo
aims: We determine the solar abundance of phosphorus using co5bold 3D hydrodynamic model atmospheres. method: High resolution, high signal-to-noise solar spectra of the PI lines of Multiplet 1 at...
Line shift, line asymmetry, and the 6Li/7Li isotopic ratio determination (2007)
Cayrel, Roger, Steffen, Matthias, Chand, Hum, Bonifacio, Piercarlo, Spite, Monique, Spite, François, ...
Context: Line asymmetries are generated by convective Doppler shifts in stellar atmospheres, especially in metal-poor stars, where convective motions penetrate to higher atmospheric levels. Such...
Line shift, line asymmetry, and the 6Li/7Li isotopic ratio determination (2007)
Cayrel, Roger, Steffen, Matthias, Chand, Hum, Bonifacio, Piercarlo, Spite, Monique, Spite, François, ...
Context: Line asymmetries are generated by convective Doppler shifts in stellar atmospheres, especially in metal-poor stars, where convective motions penetrate to higher atmospheric levels. Such...
The solar photospheric abundance of phosphorus: results from co5bold 3D model atmospheres (2007)
Caffau, Elisabetta, Steffen, Matthias, Sbordone, Luca, Ludwig, Hans-G., Bonifacio, Piercarlo
aims: We determine the solar abundance of phosphorus using co5bold 3D hydrodynamic model atmospheres. method: High resolution, high signal-to-noise solar spectra of the PI lines of Multiplet 1 at...
Sulphur abundances from the SI near-infrared triplet at 1045 nm (2007)
Caffau, Elisabetta, Faraggiana, Rosanna, Bonifacio, Piercarlo, Ludwig, Hans-G., Steffen, Matthias
context : Unlike silicon and calcium, sulphur is an alpha-element which does not form dust. Some of the available observations of the evolution of sulphur with metallicity indicate an increased...
3D-Spectroscopy of extragalactic planetary nebulae as diagnostic probes for galaxy evolution (2006)
Kelz, Andreas, Monreal-Ibero, Ana, Roth, Martin M., Sandin, Christer, Schoenberner, Detlef, Steffen, Matthias
In addition to study extragalactic stellar populations in their integrated light, the detailed analysis of individual resolved objects has become feasible, mainly for luminous giant stars and for...
State tomography of capacitively shunted phase qubits with high fidelity (2006)
Steffen, Matthias, Ansmann, M., McDermott, R., Katz, N., Bialczak, Radoslaw C., Lucero, Erik, ...
We introduce a new design concept for superconducting quantum bits (qubits) in which we explicitly separate the capacitive element from the Josephson tunnel junction for improved qubit performance....
Decoherence in Josephson Qubits from Dielectric Loss (2005)
Martinis, John M., Cooper, K. B., McDermott, R., Steffen, Matthias, Ansmann, Markus, Osborn, K., ...
Dielectric loss from two-level states is shown to be a dominant decoherence source in superconducting quantum bits. Depending on the qubit design, dielectric loss from insulating materials or the...
NMR Quantum Information Processing (2004)
Ramanathan, Chandrasekhar, Boulant, Nicolas, Chen, Zhiying, Cory, David G., Chuang, Isaac, Steffen, Matthias
Nuclear Magnetic Resonance (NMR) has provided a valuable experimental testbed for quantum information processing (QIP). Here, we briefly review the use of nuclear spins as qubits, and discuss the...
Cooper, K. B., Steffen, Matthias, McDermott, R., Simmonds, R. W., Oh, Seongshik, Hite, D. A., ...
We have detected coherent quantum oscillations between Josephson phase qubits and microscopic critical-current fluctuators by implementing a new state readout technique that is an order of magnitude...
Wedemeyer, Sven, Freytag, Bernd, Steffen, Matthias, Ludwig, Hans-Günter, Holweger, Hartmut
Three-dimensional numerical simulations with CO5BOLD, a new radiation hydrodynamics code, result in a dynamic, thermally bifurcated model of the non-magnetic chromosphere of the quiet Sun. The 3-D...
Experimental implementation of an adiabatic quantum optimization algorithm (2003)
Steffen, Matthias, Van Dam, Wim, Hogg, Tad, Breyta, Greg, Chuang, Isaac
We report the realization of a nuclear magnetic resonance computer with three quantum bits that simulates an adiabatic quantum optimization algorithm. Adiabatic quantum algorithms offer new insight...
Modelling the Chromospheric Background Pattern of the Non-magnetic Sun (2003)
Wedemeyer, Sven, Freytag, Bernd, Steffen, Matthias, Ludwig, Hans-Günter, Holweger, Hartmut
Not Available
3D Simulation of the Solar Granulation: A Comparison of two Different Hydrodynamics Codes (2003)
Steffen, Matthias, Ludwig, Hans-Günter, Freytag, Bernd
Not Available
3D Hydrodynamical Modelling of the Solar Chromosphere (2003)
Ludwig, Hans-Günter, Steffen, Matthias, Wedemeyer, Sven, Freytag, Bernd, Holweger, Hartmut
We report on 3D radiation-hydrodynamics modelling of the non-magneticsolar atmosphere with emphasis on the problem of the acoustic heating ofthe chromosphere. Our models include the generation of...
A prototype quantum computer using nuclear spins in liquid solution / (2003)
Steffen, Matthias., Harris, James S. Advisor
Submitted to the Department of Electrical Engineering.
Vandersypen, Lieven M. K., Steffen, Matthias, Breyta, Gregory, Yannoni, Costantino S., Sherwood, Mark H., Chuang, Isaac L.
The number of steps any classical computer requires in order to find the prime factors of an $l$-digit integer $N$ increases exponentially with $l$, at least using algorithms known at present....
Acoustic Energy Generated by Convection: 3-D Numerical Simulations for the Sun (2001)
Wedemeyer, Sven, Freytag, Bernd, Holweger, Hartmut, Ludwig, Hans-Günter, Steffen, Matthias
Dissipation of acoustic waves may be an efficient heating mechanism forthe lower and middle chromosphere of the quiet Sun. The basic idea isthat turbulent motions at the top of the solar convection...
Experimental Realization of an Order-Finding Algorithm with an NMR Quantum Computer (2000)
Vandersypen, Lieven M. K., Steffen, Matthias, Breyta, Gregory, Yannoni, Costantino S., Cleve, Richard, Chuang, Isaac L.
We report the realization of a nuclear magnetic resonance (NMR) quantum computer which combines the quantum Fourier transform (QFT) with exponentiated permutations, demonstrating a quantum algorithm...
2D Numerical Simulation of Stellar Convection (2000)
The dynamics and thermal structure of the surface layers of stars with outer convection zones can be studied in some detail by means of numerical simulations of time-dependent compressible...
On the Transition from AGB Stars to Planetaries: The Spherical Case (1999)
Schoenberner, Detlef, Steffen, Matthias
We discuss the basic physical model and the relevant processes responsible for creating and shaping planetary nebulae out of a cool AGB wind envelope. We show that a hydrodynamical treatment along...
Implementation of a three-quantum-bit search algorithm (1999)
Vandersypen, Lieven M. K., Steffen, Matthias, Sherwood, Mark H., Yannoni, Costantino S., Breyta, Gregory, Chuang, Isaac L.
We report the experimental implementation of Grover's quantum search algorithm on a quantum computer with three quantum bits. The computer consists of molecules of $^{13}$C-labeled CHFBr$_2$, in...
Leipzig, Universiẗat, Diss., 1996.
A model atmosphere analysis of the F5 [F] IV-V subgiant Procyon. (1983)
Besteht aus 1 Mikrofiche