Synopsis: The Quantum Hall Effect Leaves Flatland

Cold atoms in an optical lattice with a synthetic extra dimension could be used to see the 4D version of the quantum Hall effect.  
Synopsis figure
Oded Zilberberg /ETH

The quantum Hall effect (QHE) is now sufficiently “standard” that it’s the basis for a unit of measure (the ohm). But more exotic offshoots of this famously 2D phenomenon have yet to be explored, such as a 4D version predicted in 2001. This hyperdimensional “topological” material is predicted to host relativistic-like particles that carry electric current along its 3D surfaces, an effect that’s difficult to isolate in a regular solid. A way to observe the 4DQHE in a cold atomic system has now been proposed by a team of theorists from the Bose-Einstein Condensate Center in Trento, Italy, the Swiss Federal Institute of Technology (ETH) in Zurich, and the Université libre de Bruxelles, Belgium.

The 4DQHE can emerge in a 4D lattice when magnetic fields pierce two orthogonal lattice planes. To engineer an analogous situation in an atomic system, the authors imagine trapping atoms in a 3D optical lattice and then stretching it into a synthetic fourth dimension. This is possible thanks to a relatively new approach that involves using a laser to couple the internal states of an atom in such a way as to simulate the presence of an extra spatial dimension. Finally, the researchers would harness established atom-manipulation techniques based on lasers to generate “artificial” magnetic fields.

If experimentalists implement this idea, they’ll need a measurable signature of the 4DQHE in a 4D lattice. The authors suggest detecting the speed with which an atom cloud drifts through the lattice, as its value should be characteristic of the 4DQHE topology.

This research is published in Physical Review Letters.

–Jessica Thomas


Features

More Features »

Announcements

More Announcements »

Subject Areas

Atomic and Molecular PhysicsCondensed Matter Physics

Previous Synopsis

Cosmology

Valuable Voids

Read More »

Next Synopsis

Fluid Dynamics

Twisted Fluid Flows

Read More »

Related Articles

Focus: Magnetic Fluctuations without a Magnet
Condensed Matter Physics

Focus: Magnetic Fluctuations without a Magnet

Magnetic waves in a permanent magnet can survive even when the material is too hot for large-scale magnetism to exist. Read More »

Focus: Ultrafast Switch with Organic Crystal
Condensed Matter Physics

Focus: Ultrafast Switch with Organic Crystal

An organic crystal was switched between paraelectric and ferroelectric states in a picosecond. Similar materials could eventually serve as extremely fast digital switches. Read More »

Synopsis: Dirac Cones in Boron’s Version of Graphene
Materials Science

Synopsis: Dirac Cones in Boron’s Version of Graphene

A one-atom-thick sheet of boron atoms exhibits Dirac cones, marking the first time this electronic property has been found in a material lacking a graphene-like crystal structure.  Read More »

More Articles