Synopsis: A Quantum Quasicrystal

A theoretical analysis shows that a quantum quasicrystal could be made by tuning the interactions between ultracold atoms.
Synopsis figure
S. Gopalakrishnan et al., Phys. Rev. Lett. (2013)

A quasicrystal has an ordered atomic arrangement that never repeats itself. This anomalous structure results in unusual material properties, such as high mechanical strength and poor electrical conduction. But so far, quasicrystalline behavior has not been observed in a quantum system, where the atomic wave functions have a coherent relationship. A group of theorists—writing in Physical Review Letters—explore the possibility of a quantum quasicrystal made from ultracold atoms. Such a system, which is presumably within reach of current experimental techniques, should exhibit excitations not seen in classical quasicrystals.

The first quasicrystals, discovered in the early 1980s, had fivefold symmetry, which implies a pentagonal pattern that does not repeat along any direction (see 7 October 2011 Nobel Focus). Since then, scientists have uncovered many other quasicrystals with a variety of nonrepeating patterns. One unique feature of these aperiodic structures is that they support phononlike excitations called phasons, in which atoms rearrange themselves from one ordered structure to another without altering the energy of the system.

Sarang Gopalakrishnan of Harvard University and colleagues model a quantum quasicrystal formed out of a two-dimensional Bose condensate of cold atoms. Typically the atoms are all in the same ground state, but the researchers assume a laser-induced spin-orbit coupling, which results in multiple ground states that form a circle in momentum phase space. The researchers also assume a strong dipole-dipole interaction, which, in certain cases, causes the atoms to collect in a handful of states that are equally spaced on the momentum circle. This momentum ordering translates into both crystalline and quasicrystalline spatial geometries. The team found that the quantum quasicrystals are unique in that they have more phasons than their classical counterparts. — Michael Schirber


More Features »


More Announcements »

Subject Areas

Atomic and Molecular Physics

Previous Synopsis


A Tripod of Light

Read More »

Next Synopsis

Related Articles

Synopsis: Quantum Sensing of Magnetic Fields
Quantum Physics

Synopsis: Quantum Sensing of Magnetic Fields

A new design for an atomic magnetometer utilizes so-called quantum nondemolition measurements to detect very weak magnetic-field signals. Read More »

Focus: New View of Cold Atoms Flowing
Atomic and Molecular Physics

Focus: New View of Cold Atoms Flowing

A new technique produces an image of the flow of cold atoms through a channel, a potentially important tool for future cold-atom technology. Read More »

Viewpoint: Seeing Scrambled Spins
Atomic and Molecular Physics

Viewpoint: Seeing Scrambled Spins

Two experimental groups have taken a step towards observing the “scrambling” of information that occurs as a many-body quantum system thermalizes.   Read More »

More Articles