"This work and a number of other recent works demonstrate that the vacuum is not empty but full of virtual photons," says theoretical physicist Steven Girvin at Yale University, who did not take part in the Aalto study.
Another study from physicist Christopher Wilson and his colleagues recently demonstrated the dynamical Casimir effect in a system mimicking a mirror moving at nearly 5 percent of the speed of light. "It's nice to see further confirmation of this effect and see this area of research continuing," says Wilson, now at the University of Waterloo in Ontario, who also did not participate in the Aalto study. "Only recently has technology advanced into a new technical regime of experiments where we can start to look at very fast changes that can have dramatic effects on electromagnetic fields," he adds.
The investigators caution that such experiments do not constitute a magical way to get more energy out of a system than what is input. For instance, it takes energy to change a material's index of refraction.
Instead, such research could help scientists learn more about the mysteries of quantum entanglement, which lies at the heart of quantum computers—advanced machines that could in principle run more calculations in an instant than there are atoms in the universe. The entangled microwave photons the experimental array generated "can be used for a form of quantum computation known as 'continuous variable' quantum information processing,” Girvin says. “This is a direction which is just beginning to open up.”
Wilson adds that these systems “might be used to simulate some interesting scenarios. For instance, there are predictions that during cosmic inflation in the early universe, the boundaries of the universe were expanding nearly at light-speed or faster than the speed of light. We might predict there'd be some dynamical Casimir radiation produced then, and we can try and do tabletop simulations of this."
So the static Casimir effect involves mirrors held still; the dynamical Casimir effect can for instance involve mirrors that move.