By the InsightArea Editorial Team
Superconductors can carry electric current without electrical resistance, but their behavior becomes more complicated in strong magnetic fields. Tiny regions called vortices can form inside them, and when those vortices move, energy can be lost. A team working in the United States and Estonia has used invisible light to study particles trapped inside these structures.
The research, described by Rutgers University on October 28, 2026, appeared in Physical Review Letters. By comparing how two thin-film samples responded to different orientations of terahertz light, the scientists distinguished two groups of trapped particles and estimated several properties of the vortices.
The finding provides a tool for investigating materials. It does not demonstrate room-temperature superconductivity or a new power cable ready for installation. The samples in this experiment had to be cooled to extremely low temperatures, and the measurements were performed under controlled laboratory conditions.
What is a superconducting vortex?
In ordinary electrical conductors, resistance causes some electrical energy to be dissipated as heat. A superconductor below its transition temperature can carry a current without that ordinary resistance. This property makes superconductors useful for powerful magnets, including those used in MRI equipment and research facilities, although maintaining the required conditions presents engineering challenges.
Many superconductors exposed to an appropriate magnetic field allow the field to enter through narrow structures known as vortices. Around each vortex, electrical current circulates; in its core, superconductivity is weakened. The material outside the cores can remain superconducting.
Vortices matter because they do not always stay still. If they move under the influence of an electrical current, their motion can produce energy losses. One goal in materials engineering is to understand and control vortex behavior so a superconductor performs reliably in the magnetic fields and currents required for a particular application.
This is a different challenge from simply finding the temperature at which a material becomes superconducting. Two samples might begin superconducting at similar temperatures and still behave differently inside a magnetic field. The internal structure and dynamics of their vortices can affect their usefulness.
What were the researchers trying to see?
Inside a vortex core, particles can occupy discrete quantum energy levels. Physicists predicted such states decades ago, and earlier experiments had detected them. The new study focused on transitions between levels and on distinguishing contributions from two different groups of particles.
A useful analogy is a ladder: a particle can occupy particular rungs and absorb an appropriate amount of energy to move between them. The analogy has limits, because the states arise from quantum behavior inside a complex material rather than from a literal mechanical ladder.
The problem for an experiment is that signals can overlap. In many conventional superconductors, the relevant energy levels are close enough together that individual contributions are hard to separate. The team chose an iron-based material with narrow vortex cores, which helped make the levels easier to distinguish, according to Rutgers.
How did light separate the signals?
Rutgers researchers prepared thin films containing iron, tellurium and selenium. The measurements were performed at the National Institute of Chemical Physics and Biophysics in Tallinn, where the team cooled the samples, applied a strong magnetic field and sent terahertz radiation through them.
Terahertz radiation is electromagnetic radiation outside the range visible to human eyes. The researchers measured how the material changed the polarization of the light, a property describing the orientation and movement of its electric field. They compared light with different handedness, analogous to clockwise and counterclockwise patterns.
Rutgers says the two groups of particles responded differently to the two light patterns. That allowed the researchers to distinguish their contributions. The team then combined measurements with mathematical calculations to estimate properties including vortex size and aspects of how the particles responded.
The experiment does not mean the scientists photographed individual particles inside a vortex in the ordinary sense. They measured a material’s response to light and interpreted that response using a physical model. The strength of the conclusion depends on how well the model accounts for the observed signals and how it compares with alternative explanations.
Why compare two recipes for the same material?
The team tested two versions of the material with different selenium content. Rutgers reports that both became superconducting at nearly the same temperature, yet the mix of trapped-particle responses differed. In one sample the calculated populations were uneven; in the other they were approximately balanced.
That comparison is valuable because it shows why a single headline number can conceal important differences. If two samples have similar transition temperatures, it is tempting to treat them as interchangeable. Their internal response to a magnetic field may tell a different story.
Changing composition can affect many properties at once, so the result should not be reduced to a universal rule that more or less selenium is always better. The experiment provides a way to examine specific samples and ask which changes produce which effects. Further studies would be needed to connect the measured properties to performance in practical devices.
Does this bring room-temperature superconductors closer?
It adds to the tools available for studying superconductors, but it does not establish a room-temperature material. Rutgers says the samples became superconducting at about minus 438 degrees Fahrenheit. Their low operating temperature is a major practical detail, not a footnote.
Room-temperature superconductivity would still face questions beyond temperature. A useful material must work under practical pressure, carry sufficient current, tolerate relevant magnetic fields and be manufacturable. It must also retain those properties in a form suitable for the intended device.
Even when a superconductor works well at low temperatures, engineers must account for cooling systems, mechanical support, connections and maintenance. Measuring a microscopic property can inform that work, but it does not automatically resolve those system-level constraints.
What would researchers do next?
The authors say the approach could be applied to other superconductors with sufficiently narrow vortex cores. Comparing different materials and compositions could reveal whether the same interpretation holds more broadly and which properties are linked to useful performance.
Independent replication would also matter. Other groups can test the technique, compare it with complementary measurements and examine where its assumptions cease to work. A measurement method becomes more valuable when researchers know both its precision and its limitations.
Another useful step would be to connect the microscopic observations with measurable device behavior. For example, does a change in the observed particle populations correspond to a predictable change in vortex motion or energy loss under relevant conditions? That is a separate question from detecting the populations themselves.
The research illustrates how progress in materials science often happens: not through a single announcement that solves every engineering problem, but by making a hidden part of a material measurable. A clearer view inside vortices gives scientists a better basis for testing which changes help—and which do not.
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