3 min read
Researchers at the University of British Columbia (UBC) believe they’ve cracked a long-standing puzzle in physics. By using thin films of superfluid helium, they’ve managed to mimic the elusive Schwinger effect, a phenomenon once thought to be unreachable outside theory. Instead of electron-positron pairs emerging from a vacuum, the UBC model shows vortex pairs appearing spontaneously, offering a fresh perspective on both cosmic mysteries and quantum materials.
Julian Schwinger first proposed the idea in 1951. He theorized that a powerful, uniform electric field applied to a vacuum could trigger the creation of matter from nothing. In this scenario, electron-positron pairs would form through quantum tunneling. The catch? The required electric fields are so immense that no laboratory on Earth could ever achieve them. For decades, that made the so-called Schwinger effect an elegant but untouchable idea.
The new UBC research, however, offers a creative workaround. Instead of an unreachable vacuum experiment, physicists replaced the background field with the flow of superfluid helium. When this frictionless liquid is cooled to just a few atomic layers thick, it behaves like a vacuum. Under those conditions, vortex and anti-vortex pairs appear spontaneously, spinning in opposite directions.
“Superfluid Helium-4 is a wonder,” says Dr. Philip Stamp, a UBC theorist working on condensed matter and quantum gravity. “At a few atomic layers thick, it can be cooled very easily to a temperature where it’s basically in a frictionless vacuum state. When we make that flow, instead of electron-positron pairs appearing, vortex/anti-vortex pairs will appear spontaneously.”
Dr. Stamp and his colleague Michael Desrochers detailed their work in a study published September 2 in PNAS. Their paper not only outlines the math but also sketches a roadmap for real-world experiments.
Quantum tunneling lies at the heart of this work. In physics, a vacuum isn’t space but a sea of fluctuating fields. Those fluctuations can briefly give rise to virtual particles, a process researchers have long wanted to probe more deeply.
According to Dr. Stamp, the thin Helium-4 films provide more than a physics demo. They create a platform to study analogs of otherwise unreachable phenomena, such as quantum black holes, the vacuum of deep space, or even the early universe itself. Still, he insists the biggest breakthrough lies in how this theory reshapes our understanding of superfluids and phase transitions in two-dimensional systems. “These are real physical systems in their own right, not just analogs. And we can actually do experiments on these,” he explains.
To build their model, the researchers had to rethink some of the fundamentals. Previous studies assumed the mass of vortices in superfluids was constant. Stamp and Desrochers showed that vortex mass can shift dramatically as vortices move, a result with implications stretching from fluid dynamics to early-universe physics.
“It’s exciting to understand how and why the mass varies and how this affects our understanding of quantum tunneling processes, which are everywhere in physics, chemistry, and biology,” says Desrochers.
Stamp also argues that this same mass variability will apply to electron-positron pairs in the original Schwinger effect, subtly rewriting Schwinger’s theory in what he calls a “revenge of the analog.”
The research was supported by Canada’s National Science and Engineering Research Council. Beyond the analogies and cosmic parallels, this work may redefine how scientists view superfluids, vortices, and even the act of quantum tunneling itself.
