In recent years, it has become increasingly possible to control individual atoms and molecules in a targeted manner. So-called “optical tweezers” – special laser beams that can be used to manipulate matter with precision – have played an important role in this development. Andreas Schindewolf wants to take this a step further: his work shows that molecules can be coupled together at surprisingly large distances using microwaves. This should make it possible to assemble them into a “quantum crystal” that will enable completely new experiments in quantum research.

To implement this project, Andreas Schindewolf has now been awarded an ERC Starting Grant, one of the most highly endowed and prestigious grants in the European research landscape.

A new type of crystal

“We can prepare individual atoms in a precisely defined quantum state,” says Andreas Schindewolf. “We can precisely control all their physical properties. This makes it possible to assemble them into a molecule in a precisely controlled manner.”

Schindewolf has selected two very special types of atoms for his future project: caesium and silver. “They combine to form a molecule with a very uneven distribution of electrical charge,” he explains. “Caesium-silver is strongly positively charged on one side and strongly negatively charged on the other.”

This also creates strong forces between the molecules that act over relatively long distances. And therefore, it should be possible to arrange caesium-silver molecules in a regular two-dimensional pattern and build an artificial “quantum crystal”.

This quantum crystal is held together by a very special type of intermolecular bond, known as a “field-bound state”: the molecules are irradiated with microwaves, causing them to align with each other with the help of the microwave field and subsequently form bonds.

Huge distances

“Our results so far show that this method should allow us to create a crystal of caesium-silver molecules in which the individual molecules are about half a micrometre apart,” says Andreas Schindewolf. “This corresponds roughly to the wavelength of visible light – much more than the usual distances in solid matter.” This means that completely new experiments can be carried out with such a quantum crystal: the molecules can be modified individually and separately from one another, and their individual and collective behaviour can be studied in detail.

“We hope to develop a platform for completely new research in this way. The list of fundamental questions we can pursue with this is long – it ranges from solid-state physics to quantum chemistry.”

Andreas Schindewolf

Andreas Schindewolf studied physics at TU Munich and wrote his thesis at the University of Strathclyde in Glasgow (UK). He then moved to Innsbruck, where he obtained his doctorate in 2018. As a postdoc, he first conducted research in Innsbruck, then at the Max Planck Institute for Quantum Optics in Garching, Germany. In 2024, he finally joined the Atomic Institute at TU Wien. There, with the help of the ERC grant, he will now expand his research group and work on the realisation of novel quantum crystals.

Contact

Andreas Schindewolf, PhD 
Institute for Atomic and Subatomic Physics
TU Wien
andreas.schindewolf@tuwien.ac.at

Text: Florian Aigner