Invisible Light Exposes Quantum States Inside Superconducting Vortices
Scientists using terahertz radiation and ultra-thin iron-based films have peered inside microscopic magnetic vortices within superconductors to measure trapped quantum particles. The experiment, published in Physical Review Letters, successfully distinguished two separate groups of particles confined inside these swirling electrical currents. Superconductors carry electricity without losing energy as heat, making them vital for particle accelerators and MRI scanners. However, external magnetic fields generate tiny vortices that induce energy losses when they move. Understanding the internal contents of these vortices has remained difficult because conventional techniques blur the signals of tightly packed energy levels.
Terahertz Radiation Separates Trapped Particle Groups
Researchers at the National Institute of Chemical Physics and Biophysics in Tallinn, Estonia, cooled superconducting film samples inside powerful magnetic fields. The team passed terahertz radiation through the films and measured changes in the polarization of the invisible light. Light waves vibrating in patterns that turn clockwise or counterclockwise interacted differently with the trapped particles. One group of particles responded to the left-handed light pattern, while the other group responded to the light. This polarization split allowed the international team to observe each particle group independently. According to Girsh Blumberg—a Distinguished Professor in the Department of Physics and Astronomy within the Rutgers School of Arts and Sciences—prior techniques were capable of spotting trapped states, yet they lacked the ability to show this differentiation with the same directness.
Atomic Layer Deposition Yields Ultra-Clean Superconducting Films
The experiment required precise material fabrication to prevent structural flaws from scrambling delicate quantum signatures. The necessary samples were fabricated by a Rutgers group comprising Hee Taek Yi, a postdoctoral research associate, alongside Seongshik Oh, a professor in the Department of Physics and Astronomy. The researchers used controlled atomic layer-by-layer deposition to build iron, tellurium, and selenium films measuring 40 nanometers thick. This thickness kept the material roughly a thousand times thinner than a human hair and allowed the researchers to measure light passing through it. The narrow vortex cores of these iron-based materials kept the quantum energy levels far enough apart to prevent signal blurring.
Selenium Ratios Alter Internal Vortex Properties
Comparing two material versions with varying selenium amounts revealed substantial differences in internal particle composition. Both samples began carrying electricity without resistance at almost the same temperature, yet changing the recipe altered the mix of particles trapped inside the vortices. Calculations for one sample suggested there were nearly four particles of one group for every particle of the other, while in the second, the two groups were about equal in number. These compositional shifts changed the energy required for particles to jump between ladder-like quantum levels and altered how quickly their light responses faded.
Frequently Asked Questions About Superconductor Vortex Research
How thick were the superconducting films used in the experiment?
The Rutgers team produced iron, tellurium, and selenium films measuring 40 nanometers thick, which is roughly a thousand times thinner than a human hair.
At what temperature did the material samples become superconducting?
Both material samples became superconducting at about minus 438 degrees Fahrenheit after being cooled and exposed to powerful magnetic fields in Tallinn, Estonia.
What specific type of invisible light was passed through the films?
By shining terahertz radiation—a type of invisible light—through the films, the researchers tracked variations in the orientation of its electric field, known as polarization.