Far from being a science about nothing, the “material” within the empty space of vacuums between the two metal plates, because of quantum effects, are actually rivers teeming with an invisible force — electromagnetic waves that contain untapped energy. During the Casimir effect, as the plates are moved together, some of the waves in the vacuum are gradually squeezed out, giving more energy to their surroundings, and causing the attractive force.

The vacuum is filled with quantum fluctuations of the electromagnetic field — virtual photons that pop in and out of existence — that are assumed to behave in the same way. To make the plates repulsive and tunable, Wilczek and Jiang inserted a material between the plates that breaks this behavior. This chiralChiral comes from the Greek word meaning hand. material causes two types of photons that differ like your left and right hand, or in this case, right- and left-circular polarized photons. The material causes the photons to have different velocities that can each transfer a different amount of momentum to the plates.

Wilczek and Jiang calculated the Casimir force between two plates for two types of intervening chiral materials and at different temperatures. They found that the force could be adjusted by changing the distance between the plates or changing the strength of an applied magnetic field. They found that making these adjustments could yield a repulsive Casimir force more than three times as strong as the attractive force for the same setup in a vacuum.

“The key to realizing repulsive Casimir forces between similar objects is to insert an intermediate chiral material between them,” said Wilczek. “The chiral Casimir force has several distinctive features: It can be oscillatory, its magnitude can be large, and it can vary in response to external magnetic fields.”  

Their hope is that these results will provide physicists and engineers interested in semiconductors and nanodevices with a new way to explore the behaviors and properties of different materials at the quantum level.

“Through the connection of this force to independently measurable material properties, one obtains a wealth of predicted phenomena which directly reflect macroscopic effects of quantum fluctuations.”

And perhaps, scientists can even draw a bit of innovation inspiration by tapping into their inner Darth Vader: “Don’t underestimate the force.”

Joe Caspermeyer

Manager (natural sciences), Media Relations & Strategic Communications