arXiv subjects

Wei-Can Yang

Publications and source records attributed to Wei-Can Yang.

8 recordsLinked to original sources

arXiv2024

Dissipation and Decay of Three Dimensional Holographic Quantum Turbulence

Quantum turbulence is a far-from-equilibrium process characterized by high nonlinearity. Holographic duality provides a systematic framework for simulating the decaying $(3+1)$-dimensional quantum turbulence by numerically solving the dual Abelian-Higgs theory in a $(4+1)$-dimensional black hole background. We reveal that different types of decay behavior of the total vortex line density $L$ emerge depending on the initial vortex line density, ranging from $L\sim t^{-1.5}$ to $L\sim t^{-1}$, similar to the experimental observation of $^3$He in Phys. Rev. Lett. 96, 035301 (2006), and of $^4$He in Phys. Rev. Lett. 82, 4831 (1999) and in Phys. Rev. Lett. 118, 134501 (2017). Furthermore, by measuring the energy flux at the black hole horizon, we determine that the energy dissipation rate $dE/dt$ is proportional to the square of the total vortex line density, consistent with the vortex line decay equation proposed by W. F. Vinen and also the experimental measurement in Nature Physics 7, 473 - 476 (2011).

hep-th↗

arXiv2024

Macroscopic Efimov effect of quantized vortex

The three-body problem, from the chaotic motions of celestial bodies to complex microscopic particle interactions, has always been one of the most foundational yet intricate challenges in physics since its establishment. A key breakthrough in this domain is the Efimov effect, which represents a significant stride in what is now known as Efimov physics. Our study uncovers a macroscopic Efimov effect in a three-component Bose-Einstein Condensate (BEC) system. Through theoretical analysis and numerical simulation, it is verified that under certain conditions, three vortices form a bound state, while removing one vortex causes the others to unbind, demonstrating topological characteristics similar to the Borromean rings, hence termed the `vortex Efimov effect', signifying a novel topological phase transition. We propose several experimental approaches to realize this macroscopic Efimov effect, paving new paths not only in many-body physics but also in exploring quantum phase transitions and applications in quantum information.

hep-th↗

arXiv2024

Emergence of Large-Scale Structures in Holographic Superfluid Turbulence

In two-dimensional turbulence systems, the emergence of large-scale structures holds profound physical implications, particularly as it indicates the occurrence of inverse energy cascades, thereby garnering significant attention. In this paper, we report a novel vortex clusters formation in the background of near-extreme Reissner-Nordstr$\ddot{o}$m black hole holographic model. At temperatures nearing absolute zero, we observe not only the formation of vortex clusters but also the emergence of an inverse energy cascade. Distinct from typical quantum systems, the genesis of holographic vortex clusters is rooted in unique quantum dissipation properties, characterized by the near immobilization of vortex dipoles at low temperatures. Through a comparative analysis with the dynamics of the Gross-Pitaevskii equation, our investigation enhances the understanding of inverse energy cascades under these extreme conditions, thereby broadening our comprehension of quantum turbulence.

hep-th↗

arXiv2023

Vortex-Antivortex Lattices in a Holographic Superconductor

We employ the Einstein-Abelian-Higgs theory to investigate the structure of vortex-antivortex lattices within a superconductor driven by spatial periodic magnetic fields. By adjusting the parameters of the external magnetic field, including the period ($\mathcal{T}$) and the amplitude ($B_0$), various distinct vortex states emerge. These states encompass the Wigner crystallization state, the vortex cluster state, and the suppressed state. Additionally, we present a comprehensive phase diagram to demarcate the specific regions where these structures emerge, contributing to our understanding of superconductivity in complex magnetic environments.

hep-th↗

arXiv2022

Motion of a superfluid vortex according to holographic quantum dissipation

Vortices are topological defects associated with superfluids and superconductors, which, when mobile, dissipate energy destroying the dissipation-less nature of the superfluid. The nature of this "quantum dissipation" is rooted in the quantum physical nature of the problem, which has been subject of an extensive literature. However, this has mostly be focused on the measures applicable in weakly interacting systems wherein they are tractable via conventional methods. Recently it became possible to address such dynamical quantum thermalization problems in very strongly interacting systems using the holographic duality discovered in string theory, mapping the quantum problem on a gravitational problem in one higher dimension, having as benefit offering a more general view on how dissipation emerges from such intricate quantum physical circumstances. We study here the elementary problem of a single vortex in two space dimensions, set in motion by a sudden quench in the background superflow formed in a finite density "Reissner-Nordstrom" holographic superconductor. This reveals a number of surprising outcomes addressing questions of principle. By fitting the trajectories unambiguously to the Hall-Vinen-Iordanskii phenomenological equation of motion we find that these are characterized by a large inertial mass at low temperature that however diminishes upon raising temperature. For a weak drive the drag is found to increase when temperature is lowered which reveals a simple shear drag associated with the viscous metallic vortex cores, supplemented by a conventional normal fluid component at higher temperatures. For a strong drive we discover a novel dynamical phenomenon: the core of the vortex deforms accompanied by a large increase of the drag force.

hep-th↗

arXiv2022

Giant vortex in a fast rotating holographic superfluid

In a holographic superfluid disk, when the rotational velocity is large enough, we find a giant vortex will form in the center of the system by merging several single charge vortices at some specific rotational velocity, with a phase stratification phenomenon for the order parameter. The formation of a giant vortex can be explained as there is not enough space for a standard vortex lattice. Keep increasing the rotational velocity the giant vortex will disappear and there will be an appearance of a superfluid ring. In the giant vortex region, the number of vortices measured from winding number and rotational velocity always satisfies the linear Feynman relation. However, when the superfluid ring starts to appear, the number of vortices in the disk will decrease though the rotational velocity is increasing, where most of the order parameter is suppressed.

hep-th↗

arXiv2020

Fractional and Integer Vortex Dynamics in Strongly Coupled Two-component Bose-Einstein Condensates from AdS/CFT Correspondence

In order to study the rotating strongly coupled Bose-Einstein condensations(BEC), a holographic model defined in an AdS black hole that duals to a coupled two-component condensations in global $U(1)$ symmetry broken phase with intercomponent coupling $η$ and internal coherent coupling $ε$ is proposed. By solving the dynamics of the model, we study the process of formation and also the crossover from fractional to integer vortex phases. With changing only $η$ from zero to a finite value, fractional vortex lattices undergo a transition from hexagon to square lattice and finally to vortex sheets. By continuing to turn on $ε$, we find that two fractional vortices in different components constitute dimers, and when $η$ transcend a critical value, multi-dimer like hexamer or tetramer made up of two and three dimers appear. As $ε$ keeps increasing, some dimers rotate to adjust themselves and then constitute the lattice of integer vortices. Under an initial conditions similar to an spinor BEC vortices dynamics experiment, the appearance of disordered turbulence is found in the process of fractional vortex generation, which matches the experimental observation. While in the formation process of integer vortices, the appearance of grooves is predicted.

cond-mat.quant-gas↗

arXiv2019

Phase Separation and Exotic Vortex Phases in a Two-Species Holographic Superfluid

At a finite temperature, the stable equilibrium states of a coupled two-component superfluid with the same mass in both non-rotating and rotating cases can be obtained by studying its real time dynamics via holography, the equilibrium state is the final stable state that does not change in time anymore in the evolution process . Without rotation, the spatial phase separated states of the two components become more stable than the miscible condensates state when the direct repulsive inter-component coupling constant $η>η_c=0.05$ when the Josephson coupling $ε$ is turned off. While a finite $ε$ will always prevent the two species to be separated spatially. Under rotation, with vanishing $ε$, the quantum fluid reveals many equilibrium structures of vortex states by varying the $η$ from negative to positive, the interlaced vortex lattices undergo a phase transition to vortex sheets with each component made up of chains of single quantized vortices.

hep-th↗