# Hornberger group - Research

## Our general research interests include

**Optomechanics of nanoscale systems**

- Ro-translational friction and diffusion of rigid bodies
- Cooling nanoscale particles to the quantum ground state
- Probing macroscopic quantum superpositions

**Molecular quantum optics**

- Matter wave interferometry with macro-molecules and clusters
- Decoherence of molecular superrotors, enantiomers, and matter waves
- Entangling the motional states of material particles

**Open quantum systems and the quantum-classical borderline**

- Macroscopicity of quantum mechanical superposition tests
- Decoherence theory for realistic environments
- Emergence and characterization of pointer states

## Selection of some results (pre 2013)

Information on more recent work can be found here and at the front page.## 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, Nature Com 2011]

## Derivation of non-perturbative master equations

Combining time-dependent scattering theory and concepts from the theory of generalized continuous measurements provides a novel method of deriving nontrivial, microscopically realistic 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]

## Localization of matter waves by their own heat radiation

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]

## Observation of collisional decoherence of matter waves

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]