News
 The abstract of the upcoming talk by Andreas Osterloh

Location
The talk on June 20th will take place in MG367, 14:00  15:00.
Schedule of upcoming events
 June 20th 2012
Dr. Andreas Osterloh , "Integrable systems and quantum information"
This talk is reviewing part of my work. It starts with
spinboson models towards the Rabi model which has been
solved recently. Then, I will briefly touch the entanglement patterns
in condensed matter systems mainly as a motivation of the
rest of the talk, dedicated to genuine multipartite entanglement.
Past events
 December 1st 2011
Friedemann Queisser , "Influence of nontrivial backgrounds on vacuum decay"
For a classical field in a double well potential it
is possible to have two stable ground states.
In quantum theory, the ground state of higher energy is rendered
unstable by barrier penetration.
I will discuss the vacuum decay in de Sitter, Schwarzschildde Sitter and
ReissnerNordström spacetimes starting from a scalar field minimally
coupled to gravity.
 June 16th 2011
Friedemann Queisser , "Schwinger effect and the BoseHubbard model"
In the longwavelength limit we derive
an analogue of the Schwinger effect in the
BoseHubbard model on a tilted lattice.
The effect is not seen on the meanfield level whereas
quantum fluctuations generate particlehole pairs.
 May 12th 2011
Piotr Marecki, "Bound states of sound around a vortex"
In the talk I will discuss propagation of sound in the presence of a vortex line (simple, typical rotating superfluid configuration). I will recall the basics of the formalism of acoustic spacetimes, which provides an efficient description of this situation. I will also recall deep connections between this problem and important problems of theoretical physics such as: the AharonovBohm scattering, behavior of matter in the presence of ergoregions and propagation of quantum fields in the presence of strong background (electromagnetic or gravitational) fields. In the main part of the talk I will discuss new results about the existence and properties of states of sound "localized" very close to the vortex core. The family of these states is unusually rich, and apparently not widely known. By analogy with curved spacetimes, our results provide new insights on propagation of fields in "rotating spacetimes".
 March 10th 2011
Nicolai ten Brinke, "Entangling photons via the quantum Zeno effect"
We present an approach for entangling photons using the quantum
Zeno effect and strong twophoton absorption. The quantum Zeno ef
fect describes the suppression of the time evolution of a quantum state
by frequent measurements. This effect can be employed for entangle
ment generation, e.g., to implement a quantumCNOT gate in a linear
optics approach to quantum computing. In contrast to previous propos
als, our approach might also work in free space, i.e., without resonators
or cavities.
 January 20th 2011
Nikodem Szpak, "Relativistic Dirac fermions on onedimensional lattice"
We design a model of an optical lattice with cold atoms which is, in some approximation, formally equivalent to the discretized Dirac equation for relativistic fermions in an external electromagnetic field. It should be capable of showing phenomena known from the strong field QED, like the Schwinger effect or adiabatic spontaneous pair creation.
The main advantage of this analogue model is experimental accessibility of the strong field regime in contrast to the real QED.
In this talk we will rederive the effective FermiHubbard Hamiltonian from first principles, which plays a central role in the coldatoms/relativisticfermions analogy.
(This is a joint work with Ralf Schützhold, still in progress.)
(Presentation in PDF)