Cooling a micro-mechanical resonator by quantum back-action from a noisy qubit (2008)
Wang, Ying-Dan, Li, Yong, Xue, Fei, Bruder, C., Semba, K.
We study the different roles of qubit dephasing and relaxation in the process of cooling a mechanical resonator by quantum back-action. With a superconducting flux qubit as a specific example, we...
Koerting, V., Schmidt, T. L., Doiron, C. B., Trauzettel, B., Bruder, C.
We investigate a superconducting single-electron transistor capacitively coupled to a nanomechanical oscillator and focus on the double Josephson quasiparticle resonance. The existence of two...
Quantum Theory of Transmission Line Resonator-Assisted Cooling of a Micromechanical Resonator (2008)
Li, Yong, Wang, Ying-Dan, Xue, Fei, Bruder, C.
We propose a quantum description of the cooling of a micromechanical flexural oscillator by a one-dimensional transmission line resonator via a force that resembles cavity radiation pressure. The...
The single-atom box: bosonic staircase and effects of parity (2008)
Averin, D. V., Bergeman, T., Hosur, P. R., Bruder, C.
We have developed a theory of a Josephson junction formed by two tunnel-coupled Bose-Einstein condensates in a double-well potential in the regime of strong atom-atom interaction for an arbitrary...
Dynamic method to distinguish between left- and right-handed chiral molecules (2007)
We study quantum systems with broken symmetry that can be modelled as cyclic three-level atoms with coexisting one- and two-photon transitions. They can be selectively optically excited to any state....
Photon-Assisted Transport Through a Double Quantum Dot With a Time-dependent Interdot Barrier (2007)
Ph. Brune, C. Bruder, H. Schoeller
We study transport through two ultrasmall quantum dots with discrete energy levels to which a time-dependent field is applied (e.g., microwaves). The AC field causes photon-assisted tunneling and...
Density correlations in ultracold Fermi systems within the exact Richardson solution (2007)
Staudenmayer, S., Belzig, W., Bruder, C.
We discuss the occupation number correlations in an ultracold system of interacting fermionic atoms. For a system with a special energy-level distribution, viz. two multiply-degenerate levels,...
The connection between noise and quantum correlations in a double quantum dot (2007)
Bodoky, F., Belzig, W., Bruder, C.
We investigate the current and noise characteristics of a double quantum dot system. The strong correlations induced by the Coulomb interaction create entangled two-electron states and lead to...
Measuring the Momentum of a Nanomechanical Oscillator through the Use of Two Tunnel Junctions (2007)
Doiron, C. B., Trauzettel, B., Bruder, C.
We propose a way to measure the momentum p of a nanomechanical oscillator. The p-detector is based on two tunnel junctions in a Aharonov-Bohm-type setup. One of the tunneling amplitudes depends on...
Role of interference in quantum state transfer through spin chains (2007)
Lyakhov, A. O., Braun, Daniel, Bruder, C.
We examine the role that interference plays in quantum state transfer through several types of finite spin chains, including chains with isotropic Heisenberg interaction between nearest neighbors,...
Generalized Stern-Gerlach Effect for Chiral Molecules (2007)
Li, Yong, Bruder, C., Sun, C. P.
The Stern-Gerlach effect is well-known as spin-dependent splitting of a beam of atoms with magnetic moments by a magnetic-field gradient. Here, we show that an induced gauge potential may lead to a...
Improved position measurement of nano electromechanical systems using cross correlations (2007)
Doiron, C. B., Trauzettel, B., Bruder, C.
We consider position measurements using the cross-correlated output of two tunnel junction position detectors. Using a fully quantum treatment, we calculate the equation of motion for the density...
Temperature dependence of Coulomb drag between finite-length quantum wires (2007)
Peguiron, J., Bruder, C., Trauzettel, B.
We evaluate the Coulomb drag current in two finite-length Tomonaga-Luttinger-liquid wires coupled by an electrostatic backscattering interaction. The drag current in one wire shows oscillations as a...
Korhonen, C, Peterson, K, Bruder, C, Jung, P
Objectives: To determine adverse events associated with the use of antimalarial chemoprophylaxis in Peace Corps volunteers who have served in malaria-endemic countries 6 months or longer. Methods:...
Spin-transfer torque in magnetic multilayer nanopillars (2006)
We consider a quasi one-dimensional configuration consisting of two small pieces of ferromagnetic material separated by a metallic one and contacted by two metallic leads. A spin-polarized current is...
Electrical transport through a single-electron transistor strongly coupled to an oscillator (2006)
Doiron, C. B., Belzig, W., Bruder, C.
We investigate electrical transport through a single-electron transistor coupled to a nanomechanical oscillator. Using a combination of a master-equation approach and a numerical Monte Carlo method,...
Li, Yong, Bruder, C., Sun, C. P.
Time-dependent Fr\"ohlich transformations can be used to derive an effective Hamiltonian for a class of quantum systems with time-dependent perturbations. We use such a transformation for a system...
Use of dynamical coupling for improved quantum state transfer (2006)
We propose a method to improve quantum state transfer in transmission lines. The idea is to localize the information on the last qubit of a transmission line, by dynamically varying the coupling...
Overscreening Diamagnetism in Cylindrical Superconductor-Normal Metal-Heterostructures (2006)
Belzig, W., Bruder, C., Nazarov, Yu. V.
We study the linear diamagnetic response of a superconducting cylinder coated by a normal-metal layer due to the proximity effect using the clean limit quasiclassical Eilenberger equations. We...
Alkauskas, Audrius, Baratoff, Alexis, Bruder, C.
The mechanism of adsorption of the 1,4,5,8-naphthalene-tetracarboxylic-dianhydride (NTCDA) molecule on the Ag(110) surface is elucidated on the basis of extensive density functional theory...
Nanospintronics with carbon nanotubes (2006)
Cottet, A., Kontos, T., Sahoo, S., Man, H.T., Choi, M-S., Belzig, W., ...
Nanospintronics with carbon nanotubes (2006)
Cottet, A., Kontos, T., Sahoo, S., Man, H.T., Choi, M-S., Belzig, W., ...
Controlling spin in an electronic interferometer with spin-active interfaces (2005)
Cottet, A., Kontos, T., Belzig, W., Schonenberger, C., Bruder, C.
We consider electronic current transport through a ballistic one-dimensional quantum wire connected to two ferromagnetic leads. We study the effects of the spin-dependence of interfacial phase shifts...
Quantum state transfer in arrays of flux qubits (2005)
In this work, we describe a possible experimental realization of Bose's idea to use spin chains for short distance quantum communication [S. Bose, {\it Phys. Rev. Lett.} {\bf 91} 207901]. Josephson...
Spin filter using a semiconductor quantum ring side-coupled to a quantum wire (2005)
We introduce a new spin filter based on spin-resolved Fano resonances due to spin-split levels in a quantum ring (QR) side-coupled to a quantum wire (QW). Spin-orbit coupling inside the QR, together...
C. Bruder, Rosario Fazio, Gerd Schön
Key words Bose-Hubbard model, Josephson junction arrays, optical lattices
Density correlations in ultracold atomic Fermi gases (2004)
Belzig, W., Schroll, C., Bruder, C.
We investigate density fluctuations in a coherent ensemble of interacting fermionic atoms. Adapting the concept of full counting statistics, well-known from quantum optics and mesoscopic electron...
Effects of a nonlinear bath at low temperatures (2004)
We use the numerical flow-equation renormalization method to study a nonlinear bath at low temperatures. The model of our nonlinear bath consists of a single two-level system coupled to a linear...
Solid-State Quantum Communication With Josephson Arrays (2004)
Romito, Alessandro, Fazio, Rosario, Bruder, C.
Josephson junction arrays can be used as quantum channels to transfer quantum information between distant sites. In this work we discuss simple protocols to realize state transfer with high fidelity....
Perturbative corrections to the Gutzwiller mean-field solution of the Mott-Hubbard model (2004)
Schroll, C., Marquardt, Florian, Bruder, C.
We study the Mott-insulator transition of bosonic atoms in optical lattices. Using perturbation theory, we analyze the deviations from the mean-field Gutzwiller ansatz, which become appreciable for...
Positive cross-correlations due to Dynamical Channel-Blockade in a three-terminal quantum dot (2004)
Cottet, A., Belzig, W., Bruder, C.
We investigate current fluctuations in a three-terminal quantum dot in the sequential tunneling regime. In the voltage-bias configuration chosen here, the circuit is operated like a beam splitter,...
Effects of dephasing on shot-noise in an electronic Mach-Zehnder interferometer (2004)
Marquardt, Florian, Bruder, C.
We present a theoretical study of the influence of dephasing on shot noise in an electronic Mach-Zehnder interferometer. In contrast to phenomenological approaches, we employ a microscopic model...
Charge transport through a SET with a mechanically oscillating island (2004)
Chtchelkatchev, N. M., Belzig, W., Bruder, C.
We consider a single-electron transistor (SET) whose central island is a nanomechanical oscillator. The gate capacitance of the SET depends on the mechanical displacement, thus, the vibrations of the...
Gassmann, Hanno, Choi, Mahn-Soo, Yi, Hangmo, Bruder, C.
We study a model of a magnetic resonance force microscope (MRFM) based on the cyclic adiabatic inversion technique as a high-resolution tool to detect single electron spins. We investigate the...
Positive cross-correlations in a three-terminal quantum dot with ferromagnetic contacts (2003)
Cottet, A., Belzig, W., Bruder, C.
We study current fluctuations in an interacting three-terminal quantum dot with ferromagnetic leads. For appropriately polarized contacts, the transport through the dot is governed by a novel...
Decoherence of cold atomic gases in magnetic micro-traps (2003)
Schroll, C., Belzig, W., Bruder, C.
We derive a model to describe decoherence of atomic clouds in atom-chip traps taking the excited states of the trapping potential into account. We use this model to investigate decoherence for a...
Multiple Andreev Reflections in a Carbon Nanotube Quantum Dot (2003)
Buitelaar, M. R., Belzig, W., Nussbaumer, T., Babic, B., Bruder, C., Schoenenberger, C.
We report resonant multiple Andreev relections in a multiwall carbon nanotube quantum dot coupled to superconducting leads. The position and magnitude of the subharmonic gap structure is found to...
Variable electrostatic transformer: controllable coupling of two charge qubits (2003)
We propose and investigate a novel method for the controlled coupling of two Josephson charge qubits by means of a variable electrostatic transformer. The value of the coupling capacitance is given...
Marquardt, Florian, Bruder, C.
This paper has been retracted. The authors have discovered a possible problem in applications of the dephasing terminal approach to shot noise calculations in interference situations: Eq. (7)...
Dephasing in sequential tunneling through a double-dot interferometer (2003)
Marquardt, Florian, Bruder, C.
We analyze dephasing in a model system where electrons tunnel sequentially through a symmetric interference setup consisting of two single-level quantum dots. Depending on the phase difference...
Multiple Andreev reflections in a carbon nanotube quantum dot (2003)
Buitelaar, MR, Belzig, W, Nussbaumer, T, Babic, B, Bruder, C, Schonenberger, C
We report resonant multiple Andreev reflections in a multiwall carbon nanotube quantum dot coupled to superconducting leads. The position and magnitude of the subharmonic gap structure is found to...
Multiple Andreev reflections in a carbon nanotube quantum dot (2003)
Buitelaar, MR, Belzig, W, Nussbaumer, T, Babic, B, Bruder, C, Schonenberger, C
We report resonant multiple Andreev reflections in a multiwall carbon nanotube quantum dot coupled to superconducting leads. The position and magnitude of the subharmonic gap structure is found to...
Shot Noise and Proximity Effect in Superconductor--Normal-Metal Heterostructures (2002)
Belzig, W., Boerlin, J., Bruder, C., Nazarov, Yu. V.
Current noise provides useful information on correlations important for transport properties of mesoscopic systems. Of particular interest, both experimentally and theoretically, are heterostructures...
Josephson effect in S$_{\rm F}$XS$_{\rm F}$ junctions (2002)
Chtchelkatchev, N. M., Belzig, W., Bruder, C.
We investigate the Josephson effect in S$_{\rm F}$XS$_{\rm F}$ junctions, where S$_{\rm F}$ is a superconducting material with a ferromagnetic exchange field, and X a weak link. The critical current...
Non-Markoffian effects of a simple nonlinear bath (2002)
Gassmann, Hanno, Marquardt, Florian, Bruder, C.
We analyze a model of a nonlinear bath consisting of a single two-level system coupled to a linear bath (a classical noise force in the limit considered here). This allows us to study the effects of...
Full Counting Statistics of a Superconducting Beam Splitter (2002)
Boerlin, J., Belzig, W., Bruder, C.
We study the statistics of charge transport in a mesoscopic three-terminal device with one superconducting terminal and two normal-metal terminals. We calculate the full distribution of transmitted...
Separation quality of a geometric ratchet (2001)
Keller, C., Marquardt, Florian, Bruder, C.
We consider an experimentally relevant model of a geometric ratchet in which particles undergo drift and diffusive motion in a two-dimensional periodic array of obstacles, and which is used for the...
$\pi-0$ Transition in Superconductor-Ferromagnetic-Superconductor Junctions (2001)
Chtchelkatchev, N. M., Belzig, W., Nazarov, Yu. V., Bruder, C.
Superconductor-Ferromagnetic-Superconductor (SFS) Josephson junctions are known to exhibit a transition between $\pi$ and 0 states. In this note we find the $\pi-0$ phase diagram of an SFS junction...
Aharonov-Bohm ring with fluctuating flux (2001)
Marquardt, Florian, Bruder, C.
We consider a non-interacting system of electrons on a clean one-channel Aharonov-Bohm ring which is threaded by a fluctuating magnetic flux. The flux derives from a Caldeira-Leggett bath of harmonic...
Coherent oscillations in a Cooper-pair box (2001)
Choi, Mahn-Soo, Fazio, Rosario, Siewert, Jens, Bruder, C.
This paper is devoted to an analysis of the experiment by Nakamura {\it et al.} (Nature {\bf 398}, 786 (1999)) on the quantum state control in Josephson junctions devices. By considering the relevant...
Transport through double quantum dots. (2001)
Ziegler, R., Bruder, C., Schoeller, H.
Physical Review B, 62(2000) S.1961-70
The excitation spectrum of mesoscopic proximity structures (2000)
Pilgram, S., Belzig, W., Bruder, C.
We investigate one aspect of the proximity effect, viz., the local density of states of a superconductor-normal metal sandwich. In contrast to earlier work, we allow for the presence of an arbitrary...
Anderson-type model for a molecule adsorbed on a metal surface (2000)
We investigate a modified Anderson model to study the local density of states (LDOS) of a molecular wire adsorbed on a metal. Using a self-consistent mean-field type approach we find an exponential...
Choi, Mahn-Soo, Bruder, C., Loss, Daniel
We study a double quantum dot each dot of which is tunnel-coupled to superconducting leads. In the Coulomb blockade regime, a spin-dependent Josephson coupling between two superconductors is induced,...
Spectral Features of the Proximity Effect (1999)
Pilgram, S., Belzig, W., Bruder, C.
We calculate the local density of states (LDOS) of a superconductor-normal metal sandwich at arbitrary impurity concentration. The presence of the superconductor induces a gap in the normal metal...
Phase transition in a chain of quantum vortices (1999)
Bruder, C., Glazman, L.I., Larkin, A.I., Mooij, J.E., Van Oudenaarden, A.
Quasiclassical Green's function approach to mesoscopic superconductivity. (1999)
Belzig, W., Wilhelm, F.K., Bruder, C., Schön, G., Zaikin, A.D.
Superlattices and Microstructures, 25(1999) S.1251-88
Phase transition in a chain of quantum vortices (1998)
Bruder, C., Glazman, L. I., Larkin, A. I., Mooij, J. E., Van Oudenaarden, A.
We consider interacting vortices in a quasi-one-dimensional array of Josephson junctions with small capacitance. If the charging energy of a junction is of the order of the Josephson energy, the...
Broadening of Andreev-Bound States in d_{x^2-y^2} superconductors (1998)
Poenicke, A., Barash, Yu. S., Bruder, C., Istyukov, V.
We investigate the broadening of the bound states at an interface of an unconventional superconductor by bulk impurity scattering. We use the quasiclassical theory and include impurity scattering in...
Cold bosonic atoms in optical lattices (1998)
Jaksch, D., Bruder, C., Cirac, J. I., Gardiner, C. W., Zoller, P.
The dynamics of an ultracold dilute gas of bosonic atoms in an optical lattice can be described by a Bose-Hubbard model where the system parameters are controlled by laser light. We study the...
Diamagnetic Response of an N-S-Proximity System at Arbitrary Impurity Concentration (1998)
Belzig, W., Bruder, C., Fauchere, A. L.
We investigate the magnetic response of normal-metal--superconductor proximity systems for arbitrary concentrations of impurities and at arbitrary temperatures. Using the quasiclassical theory a...
Quasiclassical theory of twin boundaries in High-T_c superconductors (1998)
Belzig, W., Bruder, C., Sigrist, M.
We investigate the electronic structure of twin boundaries in orthorhombically distorted high-T$_c$ materials using the quasiclassical theory of superconductivity. At low temperatures we find a local...
Photon-Assisted Transport Through Ultrasmall Quantum Dots: Influence of Intradot Transitions (1997)
Brune, Ph., Bruder, C., Schoeller, H.
We study transport through one or two ultrasmall quantum dots with discrete energy levels to which a time-dependent field is applied (e.g., microwaves). The AC field causes photon-assisted tunneling...
Aharonov-Bohm-Type Oscillations of Thermopower in a Quantum Dot Ring Geometry (1996)
Blanter, Ya. M., Bruder, C., Fazio, Rosario, Schoeller, Herbert
We investigate Aharonov-Bohm-type oscillations of the thermopower of a quantum dot embedded in a ring for the case when the interaction between electrons can be neglected. The thermopower is shown to...
Local Density of States in a Dirty Normal Metal connected to a Superconductor (1996)
Belzig, W., Bruder, C., Schoen, Gerd
A superconductor in contact with a normal metal not only induces superconducting correlations, known as proximity effect, but also modifies the density of states at some distance from the interface....
Aharonov-Bohm oscillations and resonant tunneling in strongly correlated quantum dots (1995)
Bruder, C., Fazio, Rosario, Schoeller, Herbert
We investigate Aharonov-Bohm oscillations of the current through a strongly correlated quantum dot embedded in an arbitrary scattering geometry. Resonant-tunneling processes lead to a flux-dependent...
Diamagnetic Response of Normal-metal -- Superconductor Double Layers (1995)
Belzig, W., Bruder, C., Schön, Gerd
The magnetic response of a proximity-coupled superconductor-normal metal sandwich is studied within the framework of the quasiclassical theory. The magnetization is evaluated for finite values of the...
Quantum-Phase Transitions of Interacting Bosons and the Supersolid Phase (1995)
Van Otterlo, Anne, Wagenblast, Karl-Heinz, Baltin, Reinhard, Bruder, C., Fazio, Rosario, Schön, Gerd
We investigate the properties of strongly interacting bosons in two dimensions at zero temperature using mean-field theory, a variational Ansatz for the ground state wave function, and Monte Carlo...
Tunnel junctions of unconventional superconductors (1994)
Bruder, C., Van Otterlo, A., Zimanyi, G. T.
The phenomenology of Josephson tunnel junctions between unconventional superconductors is developed further. In contrast to s-wave superconductors, for d-wave superconductors the direction dependence...
Proximity Effect and Charging in Mesoscopic Normal Metal - Superconductor Junction Systems (1994)
Bruder, C., Fazio, Rosario, Schön, Gerd
Charging effects in mesoscopic junctions suppress the tunneling of electrons. In normal metal - superconductor systems they also suppress the proximity effect, thereby revealing the nature of the...
Charging Effects in Ultrasmall Quantum Dots in the Presence of Time-Varying Fields (1993)
The influence of charging effects on time-dependent transport in small semiconductor quantum dots with arbitrary level spectra is studied. Starting from an explicit time-dependent tunneling...