2017/05/31 by Igor N. Cherepanov, Mikhail Lemeshko · 21 citations
Physics and Astronomy · #Angular momentum #Atom (system on chip) #Atomic and Subatomic Physics Research #Atomic physics #Cold Atom Physics and Bose-Einstein Condensates #Condensed matter physics #Impurity #Mechanics #Molecule #Momentum (technical analysis) #Physics #Quantum mechanics #Quantum, superfluid, helium dynamics #Quasiparticle #Rotation (mathematics) #Spectral line #Spin (aerodynamics) #Superconductivity #Superfluid helium-4 #Superfluidity #Total angular momentum quantum number #Vortex #cond-mat.quant-gas #physics.atm-clus #physics.chem-ph
paper · pdf · doi:10.1103/physrevmaterials.1.035602
published in Physical Review Materials 1(3) (American Physical Society) · 7 pages + supplement
arxiv created 2017/05/31 · openalex created_date 2017/06/05 · openalex publication_date 2017/08/08 · arxiv updated 2017/08/16 · openalex updated_date 2026/08/05
The formation of vortices is usually considered to be the main mechanism of angular momentum disposal in superfluids. Recently, it was predicted that a superfluid can acquire angular momentum via an alternative, microscopic route, namely, through interaction with rotating impurities, forming so-called ``angulon quasiparticles'' [R. Schmidt and M. Lemeshko, Phys. Rev. Lett. 114, 203001 (2015)]. The angulon instabilities correspond to transfer of a small number of angular momentum quanta from the impurity to the superfluid, as opposed to vortex instabilities, where angular momentum is quantized in units of \ensuremathℏ per atom. Furthermore, since conventional impurities (such as molecules) represent three-dimensional (3D) rotors, the angular momentum transferred is intrinsically 3D as well, as opposed to a merely planar rotation which is inherent to vortices. Herein we show that the angulon theory can explain the anomalous broadening of the spectroscopic lines observed for CH3 and NH3 molecules in superfluid helium nanodroplets, thereby providing a fingerprint of the emerging angulon instabilities in experiment.