
A quantized vortex in a superfluid that retains rotational memory and exhibits unique dynamics.A superfluid vortex is a quantized whirlpool that forms in a superfluid—a fluid that flows without viscosity. Unlike classical vortices, which can have any circulation, superfluid vortices have circulation quantized in discrete units of Planck's constant divided by the mass of the constituent particles. Each vortex carries a fixed amount of angular momentum, and its core is a tiny region where the superfluid order parameter vanishes. These vortices are fundamental excitations in superfluids and superconductors, and they retain rotational memory, meaning the fluid remembers its rotation history through the presence and arrangement of vortices.
The concept of quantized vortices in superfluids was proposed by Lars Onsager in 1949 and independently by Richard Feynman in 1955. The first experimental observation was made in the 1960s in superfluid helium-4, and later in ultracold atomic gases.
When a superfluid rotates, it cannot rotate as a solid body because that would require continuous velocity gradients, which are forbidden in a frictionless flow. Instead, it forms an array of quantized vortices, each with a core of normal fluid. The circulation around each vortex is an integer multiple of the quantum of circulation. These vortices interact with each other and with boundaries, forming lattices or complex tangles. In superconductors, the same physics applies to magnetic flux lines, which are quantized vortices of supercurrent.
Superfluid vortices are used to study quantum turbulence, simulate black hole physics in laboratory experiments, and are being explored as qubits for quantum computing, as in superconducting films where magnetic vortices act as quantum bits.
In superfluid helium, a single vortex can be kilometers long if stretched, yet its core is only about one angstrom in diameter—a billion times thinner than its length.




















