Quantum Fluctuations Near Absolute Zero Visualized for the First Time
(Inside Science) -- It looks like static on a TV screen. But the noisy picture is actually something much more exciting to material scientists: the first image of quantum fluctuations -- the driving force behind quantum phase transitions, which affect certain key material properties, such as magnetism and superconductivity, that make many modern-day gadgets possible.
Quantum phase transitions are somewhat like the more familiar classical phase transitions, which occur when we boil water to make steam, or when we melt cheese over a delicious sandwich. Both describe the transition of a material’s property, such as from a solid to a liquid. But while changes in temperature -- or thermal fluctuations -- drive the vaporizing of a liquid or the melting of a solid, quantum phase transitions are driven by quantum fluctuations, which are energy fluctuations that exist everywhere.
To visualize these fluctuations, researchers from the U.S., Russia and Israel used a device known as a Superconducting Quantum Interference Device, or SQUID, to detect the extremely weak magnetic signals from a material that fluctuates between being a superconductor and an insulator when cooled down to near absolute zero. What looks like TV white noise in the image represents the flickering between different quantum phases caused by quantum fluctuations.
The new technique can help researchers better study many fundamental properties of materials, such as why certain materials are magnetic while others are not, or why certain materials are superconductors. The result was published in Nature Physics Aug. 20.