Christian Kokail, Christine Maier, Rick van Bijnen

Best Paper Award 2020

Christian Kokail, Christine Maier, Rick van Bijnen , IQOQI Innsbruck, werden für ihr Paper Self-verifying variational quantum simulation of lattice models, Nature, 569, 355 (2019), ausgezeichnet.

The world around us consists of atoms, incredibly small building blocks that make up all ordinary matter. At the scale of single atoms, the laws of quantum mechanics take control. Key properties of materials, such as the occurence of high-temperature superconductivity, or molecular structure calculations that could help explain and understand chemical reaction rates (with tremendous industrial impact), are governed deep down by fundamental quantum effects such as interference and entanglement.

However, the complexity of simulating quantum systems notoriously scales exponentially with the number of particles. For every particle that we add to a simulation, our computer has to work twice as hard, running out of resources very quickly.  One solution to this problem is to use one well-controlled quantum system in the laboratory, to simulate another. In this so-called quantum simulation, answers are measured directly, rather than calculated. The simulation platform naturally matches the required exponential complexity scaling laws, being a quantum system itself. The hope is that such devices can open up unexplored territory outside the reach of classical numerical simulations, and provide new insights into quantum matter.

In the past two decades, an enormous worldwide research effort has brought us the first functioning quantum simulations. Yet, the quantum simulators are inherently single purpose devices, with a very restricted scope of application. There also remains the question how to interpret the results if the target model is not implemented perfectly. And how can we even tell whether the final answers are correct if we cannot use computers?

The work described in the paper "Self-verifying variational quantum simulation of lattice models" bypasses these restrictions, by connecting a quantum experiment consisting of 20 ultracold ions directly to a computer. In this hybrid quantum-classical experiment the computer continuously orders measurements to be taken, and based on their outcomes it steers the control parameters of the quantum device towards interesting states of the target model. The quantum experiment is used as a quantum coprocessor, integrated in the quantum cloud at the IQOQI institute, in which quantum mechanical calculations that reach the limits of classical computers are outsourced.  Moreover, novel theoretical insights allowed to determine how correct the answers are. This is a major step forward in the long-standing problem of verifying quantum simulations.


Die Preisträgerin und die Preisträger

Christian Kokail hat das Masterstudium im Fach Technische Physik 2016 an der Technischen Universität Graz abgeschlossen und ist seit 2017 Doktorand am Institut für Quantenoptik und Quanteninformation der Universität Innsbruck.

Christine Maier hat das Masterstudium im Fach Experimentelle Quantenphysik an der Universität Innsbruck 2013 abgeschlossen. Von 2014 bis Oktober 2020 war sie Doktorandin am Institut für Quantenoptik und Quanteninformation, in der Forschungsgruppe von Prof. Rainer Blatt. Seit November 2020 arbeitet Christine Maier als quantum engineer in der Firma Alpine Quantum Technology in Innsbruck.

Rick van Bijnen hat an der Technischen Universität Eindhoven die Masterstudien in den Fächern Applied Physics und Industrial and Applied Mathematics 2008 abgeschlossen. Im Jahr 2013 promovierte er an der Technischen Universität Eindhoven im Fach Theoretische Physik.
Von Oktober 2013 bis Februar 2016 war Rick van Bijnen Gastforscher am Max-Planck-Institut für Physik komplexer Systeme in Dresden; von März 2016 bis Februar 2017 hatte Rick van Bijnen eine Postdoc-Stelle am Institut für Quantenoptik und Quanteninformation der Universität Innsbruck (in den Forschungsgruppen von Peter Zoller und Francesca Ferlaino). Seit März 2017 arbeitet Rick van Bijnen Post-doctoral researcher an diesem Institut in der Gruppe von Peter Zoller.