A new technique for studying vortices in quantum fluids has been developed by physicists at Lancaster.
Andrew Guthrie, Sergey Kafanov, Theo Noble, Yuri Pashkin, George Pickett and Viktor Tsepelin, together with scientists from Moscow State University, used tiny mechanical resonators to detect individual quantum vortices in superfluid helium .
Their work is published in the current volume of Nature communications.
This quantum turbulence research is simpler than real-world turbulence, which is seen in everyday phenomena such as surfing, fast-flowing rivers, storm clouds, or chimney smoke. Despite the fact that it is so common and found at all levels, from galaxies to the subatomic, it is still not fully understood.
Physicists know the fundamental Navier-Stokes equations that govern the flow of fluids such as air and water, but despite centuries of testing, the mathematical equations still cannot be solved.
Quantum turbulence may provide clues to an answer.
Turbulence in quantum fluids is much simpler than its classical “disordered” counterpart, and being made up of identical single quantized vortices, can be considered to provide an “atomic theory” of the phenomenon.
Useless, turbulence in quantum systems, for example in superfluid helium-4, takes place on microscopic scales, and so far scientists have not had tools with sufficient precision to probe vortices as well. small.
But now Lancaster’s team, working at a temperature of a few thousandths of a degree above absolute zero, has harnessed nanoscience to enable the detection of single quantum vortices (with core sizes equal to atomic diameters) using a nanoscale “guitar string” in the superfluid.
The way the team does this is to trap a single vortex along the length of the “chain” (a bar about 100 nanometers in diameter). The resonant frequency of the bar changes when a vortex is trapped, and so the rate of vortex capture and release can be followed, opening a window into the turbulent structure.
Dr Sergey Kafanov, who initiated this research, said: “The devices developed have many other uses, one of which is to ping the end of a partially trapped vortex to study the nanoscale oscillations of the body. vortex core. turbulence and can provide clues on how to solve these stubborn equations. “
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