Topological expenses of periodically kicked molecules

The peculiar topological properties of some types of matter have been researched for many years. Now, researchers on the Institute of Science and Technology Austria (ISTA) have found topological properties of easy diatomic molecules pushed to rotation by laser pulses.

The scientists apply related arithmetic to explain them as for stable matter techniques, thus bridging two totally different fields of physics. Their findings promise possible applications in chemistry.

Sometimes, unexpected connections between disparate analysis fields in physics can emerge. This is the case for the topological properties of quantum states in rotating molecules.

In a brand new examine, Ph.D. scholar Volker Karle, Postdoc Areg Ghazaryan, and Professor Mikhail Lemeshko from the Institute of Science and Technology Austria (ISTA), have now revealed {that a} easy rotating molecule constituted of simply two atoms can characteristic quantum states with topological properties, just like what occurs in graphene and different solid-state topological supplies.

“The interesting thing is that these two systems—a single rotating molecule and a solid sheet of graphene made from millions of carbon atoms—are very different and yet, some of their properties can be described by similar mathematics,” Karle explains. “We are building a bridge between the fields of physical chemistry and solid-state physics.”

The three researchers printed their new findings within the journal Physical Review Letters.

A doughnut stays a doughnut

“Topology is the study of the geometrical properties of an object which are unaffected by the continuous change of its shape and size. Realizing that one can classify quantum states not only by their energy and symmetry but also by their topology led to a real breakthrough in our understanding of solid-state physics in the last decades,” Lemeshko explains.

“A simple example of a topological property would be a doughnut. From a mathematical perspective, a doughnut is just a ring with one hole,” Karle provides. “No matter how you stretch or squeeze it, it remains a doughnut as long as you do not do anything as drastic as adding or removing a hole. The property of being a doughnut is therefore topologically protected from ‘small’ disturbances like changing its shape or size.”

In techniques like topological insulators, these topological results emerge from the consequences of thousands and thousands of atoms interacting with each other. However, Karle, Ghazaryan, and Lemeshko have proven that this type of phenomenon may also be present in a lot less complicated techniques like a single molecule.

Pushing a molecule with laser gentle

“The system we’re finding out is a single molecule fashioned by two atoms bonded collectively,” Karle says. The researchers created a mannequin that describes what occurs in such a molecule being pushed by brief laser pulses to make it rotate across the midpoint between the 2 atoms. “At just the right wavelength and timing of the laser pulses, we can create topologically nontrivial quantum states in the molecule that behave like to ones found in solid-state systems.”

For a long time now, scientists have studied the topological properties of many various supplies and techniques—even resulting in a Nobel Prize in 2016. However, discovering them in a system like a easy molecule permits for brand spanking new sorts of experiments and purposes.

“We are envisioning an experiment where a stream of such molecules is being shot out of a source and then hit with laser pulses,” Karle says. “They then fly into a detector where we can study their quantum states in much greater detail than what’s possible with solid-state systems.” The researchers hope to realize many extra insights from future experiments maybe laying the foundations for brand spanking new purposes in chemistry.

Controlling reactivity

Non-trivial topological properties, like those described on this new publication, may result in topologically protected quantum states. These are particularly attention-grabbing for any software that must be resilient towards outdoors disturbances like warmth, magnetic fields, or materials impurities. A widely known instance that has garnered a number of analysis curiosity throughout the previous couple of years are quantum computer systems based mostly on topological quantum bits.

However, the molecules that Karle and his colleagues are finding out would discover totally different purposes. “We hope that this analysis will enable us to higher perceive many chemical reactions and will one-day result in new methods of controlling them,” Lemeshko says. “We could use lasers to create topologically protected quantum states in molecules that increase or decrease their reactivity with other chemicals just as we need it. The topological protection would stabilize the quantum state of the molecule which would otherwise quickly vanish.”