Nagaoka ferromagnetism in large-spin systems -Fermion and Boson systems-- (2009)
Miyashita, Seiji, Ogata, Masao, De Raedt, Hans
We study magnetic properties of itinerant quantum magnetic particles described by a generalized Hubbard model with large spin ($S>1/2$) which may be realized in optical lattices of laser-cooled atom...
Origin of the Canonical Ensemble: Thermalization with Decoherence (2009)
Yuan, Shengjun, Katsnelson, Mikhail I., De Raedt, Hans
We solve the time-dependent Schrodinger equation for the combination of a spin system interacting with a spin bath environment. In particular, we focus on the time development of the reduced density...
Quantum Spinodal Phenomena (2009)
Miyashita, Seiji, De Raedt, Hans, Barbara, Bernard
We study the dynamical magnetization process in the ordered ground-state phase of the transverse Ising model under sweeps of magnetic field with constant velocities. In the case of very slow sweeps...
Extended Boole-Bell inequalities applicable to quantum theory (2009)
De Raedt, Hans, Hess, Karl, Michielsen, Kristel
We address the basic meaning of apparent contradictions of quantum theory and probability frameworks as expressed by Bell's inequalities. We show that these contradictions have their origin in the...
Quantum response to time-dependent external fields (2008)
Miyashita, Seiji, Tanaka, Shu, De Raedt, Hans, Barbara, Bernard
Recently, explicit real time dynamics has been studied in various systems. These quantum mechanical dynamics could provide new recipes in information processing. We study quantum dynamics under time...
Yuan, Shengjun, Katsnelson, Mikhail I., De Raedt, Hans
We study the decoherence of two coupled spins that interact with a spin-bath environment. It is shown that the connectivity and the coupling strength between the spins in the environment are of...
Event-by-event simulation of Einstein-Podolsky-Rosen-Bohm experiments (2007)
Zhao, Shuang, De Raedt, Hans, Michielsen, Kristel
We construct an event-based computer simulation model of the Einstein-Podolsky-Rosen-Bohm experiments with photons. The algorithm is a one-to-one copy of the data gathering and analysis procedures...
De Raedt, Hans, De Raedt, Koen, Michielsen, Kristel, Keimpema, Koenraad, Miyashita, Seiji
Inspired by Einstein-Podolsky-Rosen-Bohm experiments with photons, we construct an event-based simulation model in which every essential element in the ideal experiment has a counterpart. The model...
Event-by-event Simulation of Quantum Cryptography Protocols (2007)
We present a new approach to simulate quantum cryptography protocols using event-based processes. The method is validated by simulating the BB84 protocol and the Ekert protocol, both without and with...
Importance of bath dynamics for decoherence in spin systems (2007)
Yuan, Shengjun, Katsnelson, Mikhail I., De Raedt, Hans
We study the decoherence of two coupled spins that interact with a chaotic spin-bath environment. It is shown that connectivity of spins in the bath is of crucial importance for the decoherence of...
Domain Wall Dynamics near a Quantum Critical Point (2007)
Yuan, Shengjun, De Raedt, Hans, Miyashita, Seiji
We study the real-time domain-wall dynamics near a quantum critical point of the one-dimensional anisotropic ferromagnetic spin 1/2 chain. By numerical simulation, we find the domain wall is...
Wave Packet Propagation and Electric Conductivity of Nanowires (2003)
Maeda, Munehiko, Saito, Keiji, Miyashita, Seiji, De Raedt, Hans
We compute the electric conductivity of nanowires in the presence of magnetic domain walls by the method of wave packet propagation. We demonstrate that the propagation through the wire depends on...
Programming physical realizations of quantum computers (2001)
De Raedt, Hans, Michielsen, Kristel, Hams, Anthony, Miyashita, Seiji, Saito, Keiji
We study effects of the physical realization of quantum computers on their logical operation. Through simulation of physical models of quantum computer hardware, we analyze the difficulties that are...
On the Problem of Programming Quantum Computers (2000)
De Raedt, Hans, Hams, Anthony, Michielsen, Kristel, Miyashita, Seiji, Saito, Keiji
We study effects of the physical realization of quantum computers on their logical operation. Through simulation of physical models of quantum computer hardware, we analyse the difficulties that are...
Fast Algorithm for Finding the Eigenvalue Distribution of Very Large Matrices (2000)
A theoretical analysis is given of the equation of motion method, due to Alben et al., to compute the eigenvalue distribution (density of states) of very large matrices. The salient feature of this...
Quantum Dynamics in Nanoscale Magnets in Dissipative Environments (2000)
Miyashita, Seiji, Saito, Keiji, Kobayashi, Hiroto, De Raedt, Hans
In discrete energy structure of nanoscale magnets, nonadiabatic transitions at avoided level crossings lead to fundamental processes of dynamics of magnetizations. The thermal environment causes...
Quantum Computer Emulator (1999)
De Raedt, Hans, Hams, Anthony, Michielsen, Kristel, De Raedt, Koen
We describe a quantum computer emulator for a generic, general purpose quantum computer. This emulator consists of a simulator of the physical realization of the quantum computer and a graphical user...
Feedback Effect on Landau-Zener-Stueckelberg Transitions in Magnetic Systems (1999)
Hams, Anthony, De Raedt, Hans, Miyashita, Seiji, Saito, Keiji
We examine the effect of the dynamics of the internal magnetic field on the staircase magnetization curves observed in large-spin molecular magnets. We show that the size of the magnetization steps...
Quantum Transport in Disorderd Mesoscopic Ferromagnetic Films (1999)
Jonkers, Philip A. E., Pickering, Steven J., De Raedt, Hans, Tatara, Gen
The effect of impurity and domain-wall scattering on the electrical conductivity of disordered mesoscopic magnetic thin films is studied by use of computer simulation. The results indicate a...
Nontrivial resonance of nanoscale uniaxial magnets to alternating field (1997)
Miyashita, Seiji, Saito, Keiji, De Raedt, Hans
How nanoscale uniaxial magnets respond to an alternating field is studied by direct numerical calculation. A nontrivial oscillation of the magnetization is found, which is analyzed in terms of the...