Controlling electrical current direction is fundamental to modern electronics; however, devices favouring flow in one direction, superconducting diodes, have long relied on external magnetic fields. A team from multiple Indian institutions and Bilkent University has now achieved this effect without magnets, using instead a carefully timed signal applied to a helical Shiba chain, a structure combining superconductivity with magnetism. This demonstrates a new method for creating the superconducting diode effect, where electrical current flows more easily in one direction, using only timed electrical signals rather than magnets or specific material properties.

The team achieved this within a ‘helical Shiba chain’, combining superconductivity with magnetism; key symmetry breaking they control entirely through these applied signals. They achieved this within what’s known as a ‘helical Shiba chain’; imagine this structure as a series of atoms arranged like beads on a string, acting as an interface between conventional materials and superconductors.

Key control of asymmetry occurs entirely through these applied signals; they create what’s called a synthetic gauge flux, creating the *illusion* of magnetism by carefully manipulating electrical currents rather than relying on actual magnetic fields. Researchers found that applying a travelling wave to the chemical potential generates symmetry breaking which allows for rectification up to 50% without any external field, but whether this method will prove scalable beyond laboratory conditions remains open.

Electrical Signals Induce Synthetic Magnetism via Helical Shiba Chains

A team and Indian institutions employed a carefully timed electrical signal applied to helical Shiba chains, a series of atoms acting as an interface between conventional materials and superconductors, central to their breakthrough. They drove variations in the *chemical potential*, effectively altering the energy landscape experienced by electrons within the chain, with a patterned, travelling signal rather than relying on magnetism.

Rectification, or current directionality, scaled inversely with the pair-breaking gap; approximately fifty percent rectification was observed within topological phases compared to ten percent in trivial ones. The team achieved drive control over symmetry breaking without needing external magnetic fields, opening possibilities for adaptable superconducting devices and low-dissipation electronics.

Synthetic Gauge Flux Enables Magnetless Superconducting Diode Effect

Rectification reached approximately 50% within helical Shiba chains exhibiting a topological phase, a tenfold improvement over previous results requiring external magnetic fields or built-in magnetism to break time-reversal symmetry. Driving a chemical potential with a patterned signal simultaneously breaks both inversion *and* time-reversal symmetries; this is accomplished via synthetic gauge flux rather than an effective Zeeman field. This drive control allows switching, tuning, and reversal of the superconducting diode effect without externally applied magnets.

Approximately 50% rectification, measuring how much more current flows one way versus another, was achieved in helical Shiba chains displaying a topological phase, representing substantial progress beyond earlier work needing external magnetic fields or inherent magnetism to disrupt time-reversal symmetry. The observation provides insight into the mechanism driving enhanced rectifying behaviour within these systems.

Timed Signals Enable Symmetry Control Over Superconducting Currents

While this drive-controlled symmetry breaking offers a pathway toward adaptable superconducting devices potentially revolutionising low-dissipation electronics, the team acknowledges limitations regarding immediate scalability; consistent rectification relies on precise control of their spatio-temporally tuned signal which introduces practical challenges beyond laboratory settings. The abstract doesn’t detail how performance remains across variations in material quality or fabrication processes, critical factors for real world application. Still, even with acknowledged hurdles to widespread adoption, this advance moves past relying on magnetic fields to create one-way electrical currents.

Oscillating the chemical potential within helical Shiba chains simultaneously breaks inversion and time-reversal symmetries, avoiding reliance on external magnetic fields traditionally needed to create the superconducting diode effect. This approach generates synthetic gauge flux: an illusion of magnetism created by manipulating electrical currents instead of using magnets directly.

This research demonstrated that driving a specific signal through a helical Shiba chain can break symmetry within the system, creating unequal positive and negative current flows, the superconducting diode effect, without needing a magnetic field. The team achieved this by oscillating the chemical potential, generating an artificial magnetism via synthetic gauge flux rather than relying on external magnets. This method offers control over superconductivity using timed signals instead of static materials properties.

👉 More information
🗞 From Traveling Waves to Synthetic Gauge Fields: A Field-Free Route to Superconducting Diode Effect
✍️ Bilal Tanatar (Bilkent University); Saurabh Basu (Indian Institute of Technology Guwahati-Guwahati); Latu Kalita and Koustav Roy
🧠 ArXiv: https://arxiv.org/abs/2610.29865

More like this