Slovenian preprint claims light-programmable superconductivity in aluminium–silicon devices

Researchers in Slovenia have posted an arXiv preprint claiming they can create, tune and erase a persistent superconducting state in aluminium-silicon devices using ultrafast laser pulses, with transport measurements that the authors say show zero resistance and critical temperatures as high as 8.5 kelvin. But the work has not been peer-reviewed or independently replicated, and its central claims remain unconfirmed.

That caveat matters because most earlier reports of light-induced or light-enhanced superconducting behavior — an area that has drawn attention since at least 2011 — have been transient, lasting only briefly or being inferred indirectly from optical signals. By contrast, this new paper claims a write-and-erase superconducting state that persists after the light is turned off.

The paper, posted on arXiv as “A programmable superconductor created by light” and titled in the PDF “Phase coherence control of a programmable high-Tc superconductor created by light,” is identifier 2607.14567. It was first submitted July 16 and revised July 29. The authors include researchers from the Jožef Stefan Institute, the University of Ljubljana Faculty of Mathematics and Physics, and CENN Nanocenter, all in Slovenia, including Viktoria Yursa, Igor Vaskivskyi, Tomaž Mertelj, Mikhail Feigel’man and Dragan Mihailovic.

“Here we report for the first time on a complex but robust light-programmable superconducting (LiPS) state at an aluminium-silicon heterojunction that is created and fully controlled with femtosecond laser pulses,” the authors write in the abstract.

According to the preprint, the team built nanofabricated four-probe devices from roughly 15-nanometer-thick aluminium films deposited on etched Si(100) substrates. They then exposed the structures to 220-femtosecond laser pulses at 1035 nanometers, using tailored pulse sequences that included what the paper describes as training bursts.

The core claim is that laser exposure leaves the devices in a superconducting state, meaning electrical resistance falls to zero in transport measurements. The authors report superconducting critical temperatures — the temperature below which a material becomes superconducting — ranging from about 1.8 K to 8.5 plus or minus 0.2 K. “The superconducting critical temperatures — ranging from 1.8 to 8.5 K, can be increased or erased at will by the application of tailored pulse sequences,” the abstract says.

The preprint describes the state as metastable, meaning not permanent but long-lived under the right conditions. The authors say it remains stable on laboratory timescales as long as the device is kept below about 50 K, but disappears after an extended period of more than a week at 300 K, roughly room temperature.

The paper also reports magnetic-field behavior that the authors interpret as vortex pinning and creep, effects often associated with superconductors and, in this case, with what they describe as a two-dimensional phase-coherent system.

As for why light would have such an effect, the authors point to the aluminium-silicon interface. High-resolution electron microscopy, they say, shows a Moiré-like superlattice of misfit dislocations — a repeating defect pattern where the two materials do not line up perfectly. The preprint argues that laser pulses can restructure that interfacial pattern, changing the superconducting behavior of the device.

The temperature claim is one reason the paper is likely to face close scrutiny. Bulk aluminium becomes superconducting at about 1.2 K. Thin-film or disordered aluminium can reach roughly 2 to 3 K in some reported cases, but 8.5 K in an aluminium-based system would be highly unusual.

The preprint includes transport data, microscopy and modeling, but as of July 30 it remains a preprint only. There is no peer-reviewed journal publication yet and no independent replication. If later work supports the findings, optical control over superconductivity could be relevant for cryogenic electronics, including superconducting and quantum circuits. For now, the result stands as a striking but unverified claim.