A device made of multilayer graphene exhibits topologically protected edge currents whose direction can be switched using an electric field.

Topological phases of matter have captivated physicists for several decades, promising exotic phenomena and new paradigms for electronic devices [1]. So-called Chern insulators—systems exhibiting quantized Hall conductance without an external magnetic field—are particularly enticing. These materials support dissipationless, one-way electron transport along their edges, which could enable robust low-power electronics or even form the backbone of future topological quantum-computing architectures [2]. Yet, the defining feature of a Chern insulator—its chirality, which determines the direction of the edge-state current—is set by material symmetry and is therefore notoriously rigid and difficult to manipulate dynamically [3–5].

A mysterious menagerie of quantum states — once purely theoretical — has been brought to life by researchers at Columbia using twisted molybdenum ditelluride.

These newly observed states, some never seen before, hint at the possibility of topological quantum computers that don’t require magnetic fields, overcoming a major obstacle in the field. By employing a highly sensitive optical technique, scientists have not only identified a range of exotic quantum states but also demonstrated a new experimental approach that may transform the way we study quantum matter.

Quantum States: A Growing “Zoo”

Quantum technologies, which operate leveraging quantum mechanical phenomena, have the potential to outperform their classical counterparts in some optimization and computational tasks. These technologies include so-called quantum networks, systems designed to transmit information between interconnected nodes and process it, using quantum phenomena such as entanglement and superposition.

Quantum networks could eventually contribute to the advancement of communications, sensing and computing. Before this can happen, however, existing systems will need to be improved and perfected, to ensure that they can transfer and process data both reliably and efficiently, minimizing errors.

Researchers at Tsinghua University, Hefei National Laboratory and the Beijing Academy of Quantum Information Sciences recently demonstrated the coherent control of a hybrid and scalable quantum network node. Their demonstration, outlined in Nature Physics, was realized by combining solutions and techniques that they developed as part of their earlier work.