Photographs of Quantized Vortex Lines in Rotating He II

Abstract

therefore difficult to make the k = 0 extrapolation in Eq. (2) when u) -0.This molecular-dynamics calculation shows that the vaf of a dense gas at a near-critical temperature behaves asymptotically like at~3 /2 ; the value of the coefficient a can be deduced from the transport coefficients v and D. These results confirm those obtained by Alder and Wainwright 1 and by Wood 9 for systems of 500 and 4000 hard spheres.The authors are particularly grateful to L. Verlet and J. J. Weis for their help in realizing this work.*Laboratoire associg au Centre National de la Recherche Scientifique. 1 B. J. Alder and T. E. Wainwright, Phys. Rev. A 1,The unique properties of He II have been associated with the existence of a macroscopic wave function which determines the behavior of the superfluid component. From this idea Onsager 1 and Feynman 2 predicted that He II should exhibit vorticity with circulation quantized in units of h/m 9 where h is Planck's constant and m is the mass of the helium atom. For almost two decades physicists have been exploring theoretically and experimentally the phenomena associated with these vortices. 3 A wealth of convincing information is available which supports the existence of vortices, the most direct experiments being those which proved that circulation in He II is quantized 4 ' 5 and that He II comes into rotation in a series of quantum steps. 6 There has still been one experiment which has enticed workers for some time: actually to make directly visible the discrete vortex lines in the rotating He II. (An analogous experiment has been done to visualize fluxoids in a superconductor. 7 ) This Letter describes the first successful experiment which records the positions of the vortex lines in helium. We point out that according to current ideas the vortex 18 (1970). 2 J. R. Dorfman and E. G. D. Cohen, Phys. Rev. A 15, 776 (1972). 3 Y. Pomeau, Phys. Rev. A 5, 2569 (1972); M. H.

Quantum turbulence—from superfluid helium to atomic Bose–Einstein condensates

“…Feynman noted that in uniform rotation with angular velocity Ω the curl of the superfluid velocity is the circulation per unit area, and since the curl is 2Ω, a lattice of quantized vortices with number density n 0 = curlv s /κ = 2Ω/κ ("Feynman's rule") arranges itself parallel to the rotation axis [4]. Such experiments were performed for superfluid 4 He: Packard et al visualized vortex lattices on the rotational axis by trapping electrons along the cores [22,23]. This idea has also been applied to atomic BECs.…”

Electrons in Liquid Helium

“…Packard and collaborators 69) were able to photograph the places where vortex lines in rotating helium reached the free surface of the liquid. More recently, in the movies made as described in §2, one can see some electrons that move on snake-like paths through the liquid.…”

Vortex lattices in rapidly rotating Bose-Einstein condensates: Modes and correlation functions

“…Such structure was seen experimentally in superfluid helium in Refs. [1]. Rapidly rotating Bose-Einstein condensates of cold atoms [2][3][4] open up the study of the physics of vortex lattices in regimes well beyond those achievable in superfluid helium [5][6][7].…”