Physicists Mimic Schwinger Effect Using Superfluid Helium

Physicists at the University of British Columbia (UBC) have achieved a major breakthrough by simulating the Schwinger effect—a quantum phenomenon where matter is created from a vacuum—using superfluid helium. The research, published on September 2 in the Proceedings of the National Academy of Sciences, marks the first time scientists have found a practical analog for this effect, which has remained experimentally inaccessible since it was theorized by Julian Schwinger in 1951.

The Schwinger effect predicts that a sufficiently strong electric field can spontaneously generate electron-positron pairs from the vacuum, a process requiring field strengths far beyond current technological capabilities. Instead, the UBC team substituted a thin film of superfluid helium for the vacuum and used the flow of the superfluid as an analog to the electric field. In this system, pairs of vortices and anti-vortices—quantum whirlpools spinning in opposite directions—emerge spontaneously, mirroring the creation of particle-antiparticle pairs in the original Schwinger scenario.

Dr. Philip Stamp, a theorist at UBC and co-author of the study, explained that superfluid helium-4, when cooled to just a few atomic layers thick, behaves like a frictionless vacuum. "When we make that frictionless vacuum flow, instead of electron-positron pairs appearing, vortex/anti-vortex pairs will appear spontaneously," Stamp said. This approach not only provides a tangible way to study the Schwinger effect but also deepens understanding of superfluids and quantum tunneling processes.

A New Window on Quantum Tunneling

The research team’s mathematical modeling revealed that the mass of these vortices is not constant, as previously assumed, but varies dramatically as they move. This insight fundamentally changes the understanding of vortices in both fluids and cosmological contexts, and may even require modifications to Schwinger’s original theory. Dr. Michael Desrochers, co-author of the study, emphasized the broader implications: "It's exciting to understand how and why the mass varies, and how this affects our understanding of quantum tunneling processes, which are ubiquitous in physics, chemistry and biology."

Implications for Cosmology and Quantum Physics

The findings suggest that superfluid helium films could serve as analogs for a range of cosmic phenomena, including the quantum vacuum of deep space, black holes, and the early universe. While Dr. Stamp cautioned that analogs have their limitations, he stressed that these are "real physical systems in their own right, not analogs. And we can do experiments on these." The work opens new avenues for exploring quantum field theory and phase transitions in two-dimensional systems, with potential applications extending from condensed matter physics to cosmology.

The research was supported by the National Science and Engineering Research Council, and has been widely reported in both local and international science news outlets, highlighting its significance for the broader scientific community.