Synopsis: Tuning Casimir Forces

Quantum Hall effects can be exploited to tune, reverse, and even eliminate the Casimir force between two graphene sheets.

When two uncharged metallic mirrors are placed sufficiently close in a vacuum, fluctuations in the quantum vacuum field create an attractive force between them, known as the Casimir force. But if the mirrors are made of graphene, instead of a metal, something different can happen in the presence of a magnetic field. Writing in Physical Review Letters, Wang-Kong Tse and Allan MacDonald at the University of Texas at Austin investigate a possible method for controlling and even eliminating the Casimir force in this manner.

The scheme exploits the emergence of discrete Landau energy levels in graphene, arising from the quantum Hall effect induced by a strong magnetic field. The Casimir effect thus becomes dependent on the Hall conductivity, which in turn leads to the quantization of the Casimir force and allows tuning it electrically between repulsive and attractive values. The authors’ calculations show that the Casimir force can be strongly suppressed when one of the mirrors is charge neutral. The predicted effect should also hold for a sphere-and-plate mirror combination, an important geometry for studying Casimir effects due to the difficulty of keeping two planes perfectly parallel to each other.

A key motivation for suppressing the Casimir force is provided by the efforts to examine gravitational attraction at short distances (a few micrometers), over which theories have predicted non-Newtonian behavior. At these distances, the Casimir force exceeds gravitational attraction by far. The authors’ scheme would solve this problem and allow more sensitive and direct measurements of gravitational attraction. – Daniel Ucko


Announcements

More Announcements »

Subject Areas

GrapheneQuantum Physics

Previous Synopsis

Atomic and Molecular Physics

Downsizing Optical Lattices

Read More »

Next Synopsis

Related Articles

Synopsis: Graphene’s Elegant Optics Explained
Graphene

Synopsis: Graphene’s Elegant Optics Explained

Theoretical calculations anchor graphene’s simple optical absorption in its two-dimensional structure instead of its cone-shaped energy bands. Read More »

Synopsis: A New Way to Make Graphene
Graphene

Synopsis: A New Way to Make Graphene

The addition of a rapid-cooling step to the epitaxial growth of graphene on silicon carbide can yield higher-quality graphene sheets. Read More »

Viewpoint: Cold Results from Fast Lasers
Optics

Viewpoint: Cold Results from Fast Lasers

Ultrafast lasers show promise to cool down and trap atomic species inaccessible to more traditional methods. Read More »

More Articles