Quantum Information and Foundations Group – CSIC

Quantum simulators with topological light

Topological photonics quantum simulator
A quantum simulator built with light that propagates through a topological photonic crystal, interacting with trapped atoms.

An international study led by CSIC researchers has proposed the use of light confined to topological waveguides to design new quantum simulators. The results of the work, published in the journal Science Advances, could have future applications in computing and quantum simulation.

There are certain types of problems that are impossible to solve with computers conventional, such as those in which particles interact in a quantum (e.g., electrons in complex molecules or in superconducting metals) Finding efficient ways to solve these problems could open the door to designing drugs faster or being able to build systems that transmit electricity without losses (superconductors) at higher temperatures.

“To overcome this difficulty, in recent years the idea has arisen to build quantum simulators, i.e. using microscopic systems, e.g. atoms, and design the interactions so that they interact or talk to each other in a equivalent to the system we want to solve. So, by measuring in the lab properties of this quantum simulator we could understand phenomena impossible to obtain with conventional computers,” explains QUINFOG researcher Alejandro González Tudela.

One of the main challenges researchers face is how to design these interactions between atoms over long distances and also without introducing new losses in the system. One of the most widely used ways to mediate these interactions is to use light that spreads from one atom to another, establishing a communication between them. However, when light spreads in a vacuum, the probability that this communication is very small and generates additional noise that deteriorates the simulation. “In our work we have studied a system in which both problems making atoms talk through light confined to waveguides topological. In abstract terms, topology characterizes those properties that do not change by continually transforming the system. In practical terms, the character The topological nature of light is shown by the fact that it is robust to local disturbances, such as defects in the material,” the researcher adds.

The results of the study indicate that the interactions mediated by this topological light inherit its topological properties and are more robust than those could be obtained using conventional waveguides. “Beyond that robustness, in our work we see how those interactions have a very exotic form very exotic properties unmatched by any other systems, which can give rise to new states of matter yet to be explored. Furthermore, this work lays the foundation for the future extension of these concepts to the light and three dimensional topology to be able to design quantum simulators that solve more complex problems,” concludes González Tudela.

In this work also participated researchers from the Institute of Science of Materials from Madrid Miguel Bello and Gloria Platero, and researcher Juan Ignacio Cirac of the Max Planck Institute for Quantum Optics, and it is part of the efforts of the Quantum Technology Platform of the CSIC.

M. Bello, G. Platero, J. I. Cirac, and A. González-Tudela. Unconventional quantum optics in topological waveguide QED. Science Advances. DOI: 10.1126/sciadv.aaw0297