Abstracts
B.van den Broek (Greifswald)
Entanglement and positive maps
(Introductory talk)
K.H.Fichtner (Jena)
On some models of quantum teleportation
P.Gawron, J Miszczak (Gliwice)
Simulation of quantum computers: state of the art and perspectives
Problem of simulation of quantum computers will be discussed. We will
also present our quantum-octave package that perform simulation with use
of density matrices model. Some its application will be presented.
G.Giedke (Zürich)
On the role of entanglement in quantum information processing
(Introductory talk)
G.Giedke (Zürich)
Quantum computing with nuclear spins in quantum dots
R.Gohm (Greifswald)
Noncommutative symbolic coding
We give a noncommutative generalization of classical symbolic
coding in the presence of a synchronizing word. This is done by
a scattering theory for asymptotically complete transitions.
A criterion for completeness is given in terms of
an associated extended transition operator. This is joint work
with B.Kümmerer and T.Lang.
D.Janzing (Karlsruhe)
Quantum computers as nanoscopic heat engines and refrigerators -
understanding thermodynamics from its most elementary models
(Introductory talk)
It is well-known that the theory of heat and the theory of information
are strongly related since the concept `entropy' is essential for both. However,
it is often believed that this relation is
rather academic and of minor relevance from the pragmatic point of view.
In contrast, the relation is obvious in modern quantum computing research
since the same physical process may have a computer science
and a physics interpretation. For instance, a process which is
a cooling mechanism for physicists, may be considered as a data compression
algorithm for the computer scientist.
I will present a very elementary model which allows to consider appropriate
quantum algorithms as heat engines or refrigerators on the nanoscale.
The talk does not assume that thermodynamics is already known, it should rather
help to understand it.
D.Janzing (Karlsruhe)
Decomposition of time-covariant operations on quantum systems
with continuous and/or discrete energy spectrum
Every completely positive map $G$ that commutes which the Hamiltonian
time evolution is an integral or sum over CP-maps $G_\sigma$
where $\sigma$ is the energy that is transferred to or taken from the
environment.
If the spectrum is non-degenerated each $G_\sigma$ is an {\it energy shift}
followed by a {\it dephasing} channel. The Kraus operator of
the energy shift is a partial isometry which defines a translation
on $\R$ with respect to a non-translation-invariant measure.
The dephasing is given by the Hadamard product of the density operator
with a positive operator.
As an example, I calculate this decomposition explicitly for the
gaussian channel on a single mode.
For a special type of channels, a lower bound on
the quantum capacity is derived
using the
Fourier transform of the CP-map-valued measure $(G_\sigma)$.
B.Kümmerer (Darmstadt)
Noncommutative symbolic coding and preparation of states
D.Schlingemann (Braunschweig)
On the implementation of graph-codes on a one-way quantum computer
For realizing a quantum memory the encoded quantum information can be
protected against decoherence via repeated decoding and re-encoding
operations. This requires to perform fast encoding and the decoding
operations. We discuss the computational model of the one-way quantum
computer that provides fast implementations for encoding and decoding
operations. This is based on the graph code representation for stabilizer
codes, on the one hand, and the relation between graph (cluster) states and
graph codes, on the other hand.
P.Singh (Calgary)
Analysis of quantum dots in a modified Coulomb potential
(Introductory Talk)
P.Singh (Calgary)
Quantum digital signatures using fingerprinting coding states
Last change: Rolf Gohm, 07.09.04