Tuning Casimir Forces
Date: Monday, December 10, 2012 @ 21:33:22 EST
From Physics: 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