Quantum Materials Built from Scratch
In quantum many-body physics, researchers have conventionally asked a specific question: Given a particular system of interacting particles, what quantum phases can emerge? But in the past few years, attention has begun shifting to the inverse question: Given a particular quantum phase, what systems could give rise to it? Now Nicolai Lang and his colleagues at the University of Stuttgart in Germany have made progress in answering that question [1]. In their theoretical work, they have shown how simple atomic systems could be coaxed into preordained topologically ordered quantum phases, exotic states with potential applications in quantum computing.
The researchers considered arrays of atoms where each atom can be placed freely, controlled precisely, and subjected to experimentally realistic two-body interactions. Specifically, the team focused on 2D and 3D arrays in which each atom can be in either its ground state or an excited state. These atoms interact through a so-called blockade mechanism: When one atom is excited, its strong van der Waals interactions with nearby atoms shift those atoms’ energy levels enough to prevent the atoms from also being excited. A uniform, coherent coupling between the ground and excited states causes the atoms to exhibit quantum dynamics.
As an illustration, the researchers showed how such a setup could be used to achieve a specific sought-after topologically ordered quantum phase known as the toric code. They considered a 2D atomic array and introduced a particular symmetry that causes the ground state to display the toric code. The researchers note that, while idealized, their platform relies solely on physically accessible interactions, a factor that could facilitate experimental realizations in the future.
–Ryan Wilkinson
Ryan Wilkinson is a Corresponding Editor for Physics Magazine based in Durham, UK.
References
- T. F. Maier et al., “Topological order in symmetric blockade structures,” PRX Quantum 6, 030340 (2025).