A careful alignment of three powerful lasers could generate a mysterious fourth beam of light that is throttled out of the very darkness itself.
What sounds like occult forces at work has been confirmed by a simulation of the kinds of quantum effects we might expect to emerge from a vacuum when ultra-high electromagnetic fields meet.
A team of researchers from the University of Oxford in the UK and the University of Lisbon in Portugal used a semi-classical equation solver to simulate quantum phenomena in real time and in three dimensions, testing predictions on what ought to occur when incredibly intense laser pulses combine in empty space.
“This is not just an academic curiosity – it is a major step toward experimental confirmation of quantum effects that until now have been mostly theoretical,” says Oxford physicist Peter Norreys.
Laser technology has come a long way since its invention a little over half a century ago. Focussing petawatts of power in mere instants of time, they’re theorized to be capable of literally shaking matter out of the very fabric of reality itself.
What we think of as empty space is – on a quantum level – an ocean of possibility. Fields representing all kinds of physical interactions hum with the promise of particles we’d recognize as the foundations of light and the building blocks of matter itself. These virtual particles essentially pop into and out of existence in fractions of a second.
All it takes for them to manifest longer-term is the right kind of physical persuasion that discourages them from canceling one another out; the kind of persuasion a series of strong electromagnetic fields might provide when arranged in a suitable fashion, for example.
To determine whether predictions on the power of lasers could indeed generate something from nothing, Norreys and his team ran computational models based on the mathematics underpinning electromagnetic fields in a vacuum.
Plugging numbers into their solver revealed that blending three suitably strong laser beams and their electromagnetic fields can generate a level of polarization that forces virtual photons to part before they blur out of existence. Known as four-wave mixing, the scattered photons would appear as a fourth beam of light.
This kind of photon-photon scattering has long been predicted as possible, yet attempts to observe it in reality have so far proven ineffective.
“By applying our model to a three-beam scattering experiment, we were able to capture the full range of quantum signatures, along with detailed insights into the interaction region and key time scales,” says the study’s lead author, physicist Zixin Zhang at Oxford.
While the findings are all numerical for now, they do provide a more physically realistic description of what to expect than previous models. We may not need to wait all that long for the results to be put to the ultimate test either.
The Extreme Light Infrastructure project in Romania is currently home to the world’s most advanced high-power laser infrastructure, already achieving averages of around 10 petawatts in ultrashort bursts of light.
Meanwhile, the EP-OPAL project at the University of Rochester in the US has two 25-petawatt beams in the works, with photon-photon scattering experiments already being planned. The Shanghai High repetition rate X-ray Free Electron Laser and Extreme light facility in China also hopes to smash records this year, aiming for 100 petawatts using its free-electron technology.
Using nothing but photons to generate the necessary electromagnetic fields, it’s hoped the light being scattered out of the darkness won’t be hidden in a fog of other particles, finally proving once and for all that it is possible in physics to squeeze something out of nothing.
This research was published in Communications Physics.
