Sign Flip in the Casimir Force for Interacting Fermion Systems

Defying the laws of attraction

22 January 2018

Competing forces can flip the electromagnetic field that exists between conductive plates in a vacuum.

The Casimir effect is an attractive or repulsive electromagnetic force between two conductive, uncharged, plates set nanometres apart in a vacuum. The strength and direction of the force is usually dependent on the shape and position of the plates.

A team including researchers from Keio University wanted to know whether they could flip the force direction without moving the plates. They modelled a chain of fermions — elementary particles, such as electrons, that cannot occupy the same position in space — between two fixed plates in a vacuum. Increasing the pressure squashed the fermions together and forced them to interact or ‘couple’ with each other.

The team calculated a tipping point when the Casimir effect flips from attractive to repulsive, resulting from the competition between the attractive force of the Casimir effect and the repulsive force generated by the interacting fermions.

Supported content

References

1. Phys Rev Lett. 119, 031601 (2017). doi: 10.1103/physrevlett.119.031601