https://www.nature.com/articles/nature25011
Quantum Hall annexes fourth dimension
The quantum Hall effect, discovered in the 1980s, is an important fundamental effect in condensed matter physics that links topological states with electronic properties in two-dimensional systems. The quantized conductance is prescribed by an integer global topological invariant and is therefore protected against perturbations. Such invariants are characterized by a so-called Chern number. Two papers in this issue experimentally confirm the prediction that the quantum Hall effect can be generalized to a four-dimensional (4D) system. Immanuel Bloch and colleagues implement the 4D quantum Hall system in a superlattice of ultracold bosonic atoms, and Mikael Rechtsman and colleagues achieve the same in a photonic waveguide array. Both groups find that their system harbours a second Chern number, as expected. The studies show an intriguing advance towards new physics provided by topological protection in higher dimensions.
View attachment 652
Quantum Hall annexes fourth dimension
The quantum Hall effect, discovered in the 1980s, is an important fundamental effect in condensed matter physics that links topological states with electronic properties in two-dimensional systems. The quantized conductance is prescribed by an integer global topological invariant and is therefore protected against perturbations. Such invariants are characterized by a so-called Chern number. Two papers in this issue experimentally confirm the prediction that the quantum Hall effect can be generalized to a four-dimensional (4D) system. Immanuel Bloch and colleagues implement the 4D quantum Hall system in a superlattice of ultracold bosonic atoms, and Mikael Rechtsman and colleagues achieve the same in a photonic waveguide array. Both groups find that their system harbours a second Chern number, as expected. The studies show an intriguing advance towards new physics provided by topological protection in higher dimensions.
View attachment 652