Molecular quantum systems

Although various approaches to developing quantum computers have been explored for some time, the big breakthrough remains elusive. At the WSS Research Center for Molecular Quantum Systems (MolQ) researchers are now pursuing an innovative and promising new strategy for building stable, energy efficient qubits.

Scientists at MolQ are aiming to place so-called topologically protected quantum units on superconducting materials. Superconducting materials enable electricity to flow with no resistance, and topological material states are given when the complex structures of a material prevent external influences—deformations or defects—from changing the material’s basic properties.

In a first step, chemists at the University of Bern fabricate novel molecules capable of acquiring single electrons. Afterwards, physicists in Basel will fuse these molecules to a superconducting substrate, where each new molecule acquires an additional electron—and with it a magnetic moment. When the molecules are arranged in a certain way, their charges and magnetic moments generate what are called “superconducting edge currents”: an electric charge flows loss-free on the edge currents around the molecular islands. These edge currents can be used to store information, or—put differently—they function as novel qubits.

The advantages of the envisioned molecular quantum systems are far-reaching: for instance, they’re so small that there’s room for an enormous quantity on even the tiniest quantum chip. In addition, quantum computers based on superconducting technology consume significantly less energy. And importantly, topological protection ensures that the quantum states can be maintained up to one thousand times longer than with conventional methods—enabling the system to perform many more operations before an error occurs.