He – a path toward new class of 1D quantum fluids*

More than a decade long search for the explanation of the unusual thermal, pressure and bias dependencies demonstrated by the superflow-through-solid (STS) effect (M. W. Ray and R. B. Hallock, PRL. 100, 235301 (2008)) has led to the realization that superclimbing dislocation is the underlying cause for these features [1,2]. The key element -- the superfluidity along the dislocation core which induces the dislocation climb – leads to the striking differences from the Luttinger Liquid (LL) as the standard paradigm for 1D quantum fluids: i) The parabolic spectrum of excitations; ii) Long range off-diagonal order along the dislocation core at zero temperature ; iii)  Protection from the phase slips.  Our approach [1,2] is consistent with the existing experimental data ( M. W. Ray and R. B. Hallock, PRB 79, 224302 (2009); PRB 81, 214523 (2010); J. Shin, D. Y. Kim, A. Haziot, and M. H. W. Chan, PRL 118, 235301 (2017); J. Shin and M. H. W. Chan, PRB 99, 140502(R) (2019)) of the STS effect. New experiments have been proposed. Our analysis led to the realization that the quantum fluid demonstrating these features – Transverse Quantum Fluid [2,3] – can be hosted in other systems such as a superfluid edge of a self-bound droplet of hard core bosons on a two-dimensional (2D) lattice, Bloch domain wall in an easy-axis ferromagnet, phase separated state of two-component bosonic Mott insulators with the boundary in the counter-superfluid phase on a 2D lattice. It can aso occur in an ensemble of specially arranged Luttinger Liquids [3].