A novel interferometer concept will allow one to test spontaneous collapse models, which predict a modification of the superposition principle at high masses [NJP 2011, PRA 2011, RMP 2012]
Detecting entanglement in spatial interference
A separability criterion allowing one to verify continuous variable entanglement by means of simple position measurements. [PRL 2011]
Hund's paradox of molecular chirality
The emergence of super-selection rules for molecular configuration states of different chirality can be understood quantitatively by identifying the dominant decoherence mechanism, allowing us to predict the experimental confirmation of the effect. [PRL 2009]
Bell test for the motion of material particles
The novel concept of dissociation time entanglement permits one to observe nonlocal correlations in the dispersing motional state of free material particles. Our experimental proposal is based on a molecular Bose-Einstein condensate of fermionic lithium atoms. [PRL 2008]
Theory of the Kapitza-Dirac
Talbot-Lau-Interferometer
A
near field diffraction effect at standing light fields opens the way to
demonstrating the wave nature of particles with masses beyond 10^{4}
amu, even if the incoherent effects of photon absorption are accounted
for. [Nature Physics
2007, NJP 2009]
New approach to the derivation of
microscopically realistic,
non-perturbative master equations
Combining
time-dependent scattering theory and concepts from the theory
of generalized continuous measurements leads to a novel method of
deriving
nontrivial, microscopically defined Lindblad master equations. [EPL 2007]
Quantum linear Boltzmann equation
This
equation provides the complete, non-perturbative description how a quantum tracer
particle
moves in a markovian background gas. Limiting cases yield the known dynamics of
pure collisional decoherence and the thermalising behavior as described
by the classical
linear Boltzmann equation. [PRL 2006, PhysRep 2009]
The
experimentally observed
gradual transition between the quantum and the classical behavior of
extended molecular matter waves is quantitatively explained by
evaluating the effect of their heat radiation. [Nature 2004]
Description of decoherence of a Brownian
quantum particle
The
master equation for the loss of coherence in the motional state of a
tracer particle by collisions with background gas particles is derived
stringently (correcting an earlier proposal). [PRA 2003]
The
experimentally observed localization of matter waves by collisions with
gas atoms is quantitatively explained in the framework of decoherence
theory, by calculating the molecular scattering problem. [PRL 2003]
Theory of the molecular near field
interferometer
The
coherent effect of dispersion forces and the incoherent processes
occurring in a near field matter wave
interferomer are strongly influenced by the structural properties of
the diffracted molecules. [PRA 2004, PRL 2003]
Boundary integral method for the quantization
of two-dimensional electron gases at high magnetic fields and large
energies
A
new mathematical method for the
regularization of boundary integral equations, which incorporates
hyper-singular integral operators, admits a highly efficient numerical
computation of previously inaccessible spectra and wave functions. [JPA
2000]
Semiclassical spectral theory of quantum
billiards in the magnetic field
The
physically motivated, gradual
filtering of current-carrying edge states from a spectrum dominated by
bulk states admits a semiclassical theory of the associated spectral
density, which is valid both in the integrable and the completely
chaotic case.
[PhysRep 2002]
Spectral correlations between magnetic
quantum dots and the corresponding anti-dots
Discovery
of a strong nontrivial
relationship between the spectra of magnetic
dots and their complementary anti-dots, which is based on action
correlations in the periodic
orbits of the underlying mixed-chaotic classical phase space. [PRL 2002]
Influence of environmental coupling on
coherently decaying quantum states
The
complex scaling of
Schrödinger operators with a strongly structured continuous
spectrum admits a transparent description of the interplay between the
coherent decay of resonance states and the incoherent dynamics induced
by the coupling to a Markovian bath. [EPL 1999]
Currently, I'm involved in a number of projects:
Dissociation
time
entanglement of massive
particles
with Clemens Gneiting
Hund's
paradox
and the emergence of
chirality
with Johannes Trost
Pointer
states in
microscopically realistic
environments
with Marc Busse
Talbot-Lau
interferometry beyond the eikonal
approximation
with Stefan Nimmrichter
Properties
of the
quantum linear Boltzmann
equation
with Bassano
Vacchini