'Remarkably close to the minimum permitted by physics': this superconducting memory bit runs at an estimated 5x the limit, but at -269°C the fridge shrinks its claimed million-fold edge over today’s chips considerably

A team of Hebrew University physicists has achieved a superconducting memory bit that operates remarkably close to the theoretical minimum dictated by physics, while also noting that practical limitations such as cooling costs and operational speed significantly impact efficiency. According to their study published in Nature Communications, a single superconducting vortex within a nanoscale current whirlpool can act as a memory bit at approximately five times the theoretical limit set by Landauer's principle.

This achievement was demonstrated using a 55-nanometer niobium film patterned into a strip, cooled to an extremely low temperature of 4.2 kelvin. The bit's state—represented as either zero or one—was manipulated using a steady current and then observed through a SQUID-on-tip microscope, which tracked the vortex's movements. While the paper presents an energy measurement for a bit driven at 150 kHz, it acknowledges that true erasure, required for a perfect Landauer limit, was simulated and may not reflect practical conditions.

The research, however, has sparked debate within the scientific community, with at least one reviewer questioning the method's ability to achieve the claimed efficiency at realistic speeds. The authors maintain that their findings represent a significant step towards the ultimate energy efficiency limit, despite the acknowledged trade-offs between speed, cooling costs, and data retention time.