Protected Subspaces in Quantum Information (2009)
Majgier, Krzysztof, Maassen, Hans, Zyczkowski, Karol
In certain situations the state of a quantum system, after transmission through a quantum channel, can be perfectly restored. This can be done by 'coding' the state space of the system before...
Generalised Brownian Motion and Second Quantisation (2007)
Mdlin Gu. T, Mdlin Gu, Hans Maassen, Hans Maassen
A new approach to the generalised Brownian motion introduced by M. Bo2ejko and R. Speicher is described, based on symmetry rather than deformation. The symmetrisation principle is provided by...
A Condorcet Winner, Hans Maassen, Thom Bezembinder
random weak orders and the probability of
H.: Symmetric Hilbert Spaces Arising from Species of Structures, preprint math-ph/0007005 (2007)
Hans Maassen, Mathematisch Instituut
Symmetric Hilbert spaces such as the bosonic and the fermionic Fock spaces over some `one particle space ' K are formed by certain symmetrization procedures performed on the full Fock space. We...
The q-harmonic oscillator in a lattice model (2007)
Hans Van Leeuwen, Hans Maassen
We give an explicit proof of the pair partitions formula for the moments of the q-harmonic oscillator, and of the claim made by G. Parisi that the q-deformed lattice Laplacian on the d-dimensional...
H.: Generalised Brownian Motion and Second Quantisation, preprint math-ph/0011028 (2007)
Madalin Guta, Hans Maassen, Mathematisch Instituut
A new approach to the generalised Brownian motion introduced by M. Bozejko and R. Speicher is described, based on symmetry rather than deformation. The symmetrisation principle is provided by...
Information Transfer Implies State Collapse (2006)
We attempt to clarify certain puzzles concerning state collapse and decoherence. In open quantum systems decoherence is shown to be a necessary consequence of the transfer of information to the...
Purification of quantum trajectories (2005)
Maassen, Hans, Kümmerer, Burkhard
We prove that the quantum trajectory of repeated perfect measurement on a finite quantum system either asymptotically purifies, or hits upon a family of `dark' subspaces, where the time evolution is...
Quantum probability applied to the damped harmonic oscillator (2004)
In this introductory course we sketch the framework of quantum probability in order to discuss open quantum systems, in particular the damped harmonic oscillator.
A Pathwise Ergodic Theorem for Quantum Trajectories (2004)
Kuemmerer, Burkhard, Maassen, Hans
If the time evolution of an open quantum system approaches equilibrium in the time mean, then on any single trajectory of any of its unravelings the time averaged state approaches the same...
Stochastic Schrodinger equations (2003)
Bouten, Luc, Guta, Madalin, Maassen, Hans
A derivation of stochastic Schrodinger equations is given using quantum filtering theory. We study an open system in contact with its environment, the electromagnetic field. Continuous observation of...
Constructing the Davies process of Resonance Fluorescence with Quantum Stochastic Calculus (2002)
Bouten, Luc, Maassen, Hans, Kuemmerer, Burkhard
Starting point is a given semigroup of completely positive maps on the 2 times 2 matrices. This semigroup describes the irreversible evolution of a decaying 2-level atom. Using the integral-sum...
An Ergodic Theorem for Quantum Counting Processes (2001)
Kuemmerer, Burkhard, Maassen, Hans
For a quantum-mechanical counting process we show ergodicity, under the condition that the underlying open quantum system approaches equilibrium in the time mean. This implies equality of time...
Generalised Brownian Motion and Second Quantisation (2000)
A new approach to the generalised Brownian motion introduced by M. Bozejko and R. Speicher is described, based on symmetry rather than deformation. The symmetrisation principle is provided by Joyal's...
Symmetric Hilbert spaces arising from species of structures (2000)
Symmetric Hilbert spaces such as the bosonic and the fermionic Fock spaces over some `one particle space' $\K$ are formed by certain symmetrization procedures performed on the full Fock space. We...
Stability of Bose dynamical systems and branching theory (1999)
Botvich, Dmitri, Guttcharina, Mcharinadcharinalin, Maassen, Hans
An obstruction for q-deformation of the convolution product (1995)
Van Leeuwen, Hans, Maassen, Hans
We consider two independent q-Gaussian random variables X and Y and a function f chosen in such a way that f(X) and X have the same distribution. For 0 < q < 1 we find that at least the fourth...
A q-deformation of the Gauss distribution (1995)
Hans Van Leeuwen, Hans Maassen
The q-deformed commutation relation aa #
A q-deformation of the Gauss distribution (1995)
Hans Van Leeuwen, Hans Maassen
The q-deformed commutation relation aa \Gamma qa a = 11 for the harmonic oscillator is considered with q 2 [\Gamma1; 1]. An explicit representation generalizing the Bargmann representation of...
Zur Histologie [hs. verb.:] -genese und Altersbestimmung der Geflügeltuberkulose. (1943)
Berlin, Vet.-med. F., Diss., 1943 (Nicht f. d. Austausch).
Generating random weak orders and the probability of a Condorcet winner
Thom Bezembinder, Hans Maassen
We present an algorithm for generating a random weak order of m objects in which all possible weak orders are equally likely. The form of the algorithm suggests analytic expressions for the...