Scientists at Chalmers have successfully created light from vacuum – observing an effect first predicted over 40 years ago.
In an innovative experiment, the scientists have managed to capture some of the photons that are constantly appearing and disappearing in the vacuum.
In the Chalmers scientists’ experiments, virtual photons bounce off a “mirror” that vibrates at a speed that is almost as high as the speed of light.
The experiment is based on one of the most counterintuitive, yet, one of the most important principles in quantum mechanics: that vacuum is by no means empty nothingness.
In fact, the vacuum is full of various particles that are continuously fluctuating in and out of existence. They appear, exist for a brief moment and then disappear again. Since their existence is so fleeting, they are usually referred to as virtual particles.
Chalmers scientist, Christopher Wilson and his co-workers have succeeded in getting photons to leave their virtual state and become real photons, i.e. measurable light.
The physicist Moore predicted way back in 1970 that this should happen if the virtual photons are allowed to bounce off a mirror that is moving at a speed that is almost as high as the speed of light.
The phenomenon, known as the dynamical Casimir effect, has now been observed for the first time in a brilliant experiment conducted by the Chalmers scientists.
“Since it’s not possible to get a mirror to move fast enough, we’ve developed another method for achieving the same effect,” explained Per Delsing, Professor of Experimental Physics at Chalmers.
“Instead of varying the physical distance to a mirror, we’ve varied the electrical distance to an electrical short circuit that acts as a mirror for microwaves,” he stated.
The “mirror” consists of a quantum electronic component referred to as a SQUID (Superconducting quantum interference device), which is extremely sensitive to magnetic fields. By changing the direction of the magnetic field several billions of times a second the scientists were able to make the “mirror” vibrate at a speed of up to 25 percent of the speed of light.
“The result was that photons appeared in pairs from the vacuum, which we were able to measure in the form of microwave radiation,” said Per Delsing.
“We were also able to establish that the radiation had precisely the same properties that quantum theory says it should have when photons appear in pairs in this way,” he added.
The results have been published in the journal Nature.