The Experts below are selected from a list of 72306 Experts worldwide ranked by ideXlab platform
Aurel Bulgac - One of the best experts on this subject based on the ideXlab platform.
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towards quantum turbulence in cold atomic fermionic Superfluids
arXiv: Quantum Gases, 2016Co-Authors: Aurel Bulgac, Michael Mcneil Forbes, Gabriel WlazlowskiAbstract:Fermionic Superfluids provide a new realization of quantum turbulence, accessible to both experiment and theory, yet relevant to phenomena from both cold atoms to nuclear astrophysics. In particular, the strongly interacting Fermi gas realized in cold-atom experiments is closely related to dilute neutron matter in neutron star crusts. Unlike the liquid Superfluids 4He (bosons) and 3He (fermions) where quantum turbulence has been studied in the laboratory, superfluid Fermi gases stand apart for a number of reasons. They admit a reliable theoretical description based on a DFT called the TDSLDA that describes both static and dynamic phenomena. Cold atom experiments demonstrate exquisite control over particle number, spin polarization, density, temperature, and interaction strength. Topological defects such as domain walls and quantized vortices, which lie at the heart of quantum turbulence, can be created and manipulated with time-dependent external potentials, and agree with the time-dependent theoretical techniques. While similar experimental and theoretical control exists for weakly interacting Bose gases, the unitary Fermi gas is strongly interacting. The resulting vortex line density is extremely high, and quantum turbulence may thus be realized in small systems where classical turbulence is suppressed. Fermi gases also permit the study of exotic superfluid phenomena such as a 3D LOFF supersolid, and a finite temperature pseudo-gap in the regime of classical turbulence. The dynamics associated with these phenomena has only started to be explored. Finally, superfluid mixtures have recently been realized, providing experimental access to phenomena like Andreev-Bashkin entrainment. Superfluid Fermi gases thus provide a rich forum for addressing phenomena related to quantum turbulence with applications ranging from terrestrial superfluidity to astrophysical dynamics in neutron stars.
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time dependent density functional theory and the real time dynamics of fermi Superfluids
Annual Review of Nuclear and Particle Science, 2013Co-Authors: Aurel BulgacAbstract:I describe the time-dependent superfluid local density approximation, which is an adiabatic extension of the density functional theory to superfluid Fermi systems and their real-time dynamics. This new theoretical framework has been used to describe several phenomena in cold atomic gases and nuclear collective motion: excitation of the Higgs modes in strongly interacting Fermi Superfluids, generation of quantized vortices, crossing and reconnection of vortices, excitation of the superflow at velocities above the critical velocity, excitation of quantum shock waves and domain walls in the collisions of superfluid atomic clouds, and excitation of collective states in nuclei.
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Time-Dependent Superfluid Local Density Approximation
arXiv: Quantum Gases, 2013Co-Authors: Aurel Bulgac, Michael Mcneil ForbesAbstract:The time-dependent superfluid local density approximation (TDSLDA) is an extension of the Hohenberg-Kohn density functional theory (DFT) to time-dependent phenomena in superfluid fermionic systems. Unlike linear response theory, which is only valid for weak external fields, the (TDSLDA) approach allows one to study non-linear excitations in fermionic Superfluids, including large amplitude collective modes, and the response to strong external probes. Even in the case of weak external fields, the (TDSLDA) approach is technically easier to implement. We will illustrate the implementation of the (TDSLDA) for the unitary Fermi gas, where dimensional arguments and Galilean invariance simplify the form of the functional, and ab initio input from (QMC) simulations fix the coefficients to quite high precision.
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time dependent density functional theory and the real time dynamics of fermi Superfluids
arXiv: Quantum Gases, 2013Co-Authors: Aurel BulgacAbstract:I describe the Time-Dependent Superfluid Local Density Approximation, which is an adiabatic extension of the Density Functional Theory to superfluid Fermi systems and their real-time dynamics. This new theoretical framework has been applied to describe a number of phenomena in cold atomic gases and nuclear collective motion: excitation of the Higgs modes in strongly interacting Fermi Superfluids, generation of quantized vortices, crossing and reconnection of vortices, excitation of the superflow at velocities above the critical velocity, excitation of quantum shock waves and domain walls in the collisions of superfluid atomic clouds, excitation of collective states in nuclei.
G. V. Shlyapnikov - One of the best experts on this subject based on the ideXlab platform.
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Novel p-wave Superfluids of fermionic polar molecules.
Scientific reports, 2016Co-Authors: Aleksey K. Fedorov, V. I. Yudson, Sergey Matveenko, G. V. ShlyapnikovAbstract:Recently suggested subwavelength lattices offer remarkable prospects for the observation of novel Superfluids of fermionic polar molecules. It becomes realistic to obtain a topological p-wave superfluid of microwave-dressed polar molecules in 2D lattices at temperatures of the order of tens of nanokelvins, which is promising for topologically protected quantum information processing. Another foreseen novel phase is an interlayer p-wave superfluid of polar molecules in a bilayer geometry.
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Novel $p$-wave Superfluids of fermionic polar molecules
Scientific Reports, 2016Co-Authors: Aleksey K. Fedorov, V. I. Yudson, Sergey Matveenko, G. V. ShlyapnikovAbstract:We show that recently suggested subwavelength lattices offer remarkable prospects for the observation of novel Superfluids of fermionic polar molecules. It becomes realistic to obtain a topological $p$-wave superfluid of microwave-dressed polar molecules in 2D lattices at temperatures of the order of tens of nanokelvins, which is promising for topologically protected quantum information processing. Another foreseen novel phase is an interlayer $p$-wave superfluid of polar molecules in a bilayer geometry.
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interlayer superfluidity in bilayer systems of fermionic polar molecules
Physical Review Letters, 2010Co-Authors: Alexander Pikovski, G. V. Shlyapnikov, M Klawunn, L SantosAbstract:We consider fermionic polar molecules in a bilayer geometry where they are oriented perpendicularly to the layers, which permits both low inelastic losses and superfluid pairing. The dipole-dipole interaction between molecules of different layers leads to the emergence of interlayer Superfluids. The superfluid regimes range from BCS-like fermionic superfluidity with a high Tc to Bose-Einstein (quasi-)condensation of interlayer dimers, thus exhibiting a peculiar BCS-Bose-Einstein condensation crossover. We show that one can cover the entire crossover regime under current experimental conditions.
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Interlayer superfluidity in bilayer systems of fermionic polar molecules
Physical Review Letters, 2010Co-Authors: Alexander Pikovski, G. V. Shlyapnikov, M Klawunn, L SantosAbstract:We consider fermionic polar molecules in a bilayer geometry where they are oriented perpendicularly to the layers, which permits both low inelastic losses and superfluid pairing. The dipole-dipole interaction between molecules of different layers leads to the emergence of interlayer Superfluids. The superfluid regimes range from BCS-like fermionic superfluidity with a high $T_c$ to Bose-Einstein (quasi-)condensation of interlayer dimers, thus exhibiting a peculiar BCS-BEC crossover. We show that one can cover the entire crossover regime under current experimental conditions.
Giorgio Krstulovic - One of the best experts on this subject based on the ideXlab platform.
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Counterflow-Induced Inverse Energy Cascade in Three-Dimensional Superfluid Turbulence
Physical Review Letters, 2020Co-Authors: Juan Ignacio Polanco, Giorgio KrstulovicAbstract:Finite-temperature quantum turbulence is often described in terms of two immiscible fluids that can flow with a nonzero-mean relative velocity. Such out-of-equilibrium state is known as counterflow superfluid turbulence. We report here the emergence of a counterflow-induced inverse energy cascade in three-dimensional superfluid flows by performing extensive numerical simulations of the Hall-Vinen-Bekarevich-Khalatnikov model. As the intensity of the mean counterflow is increased, an abrupt transition, from a fully three-dimensional turbulent flow to a quasi-two-dimensional system exhibiting a split cascade, is observed. The findings of this work could motivate new experimental settings to study quasi-two-dimensional superfluid turbulence in the bulk of three-dimensional experiments. They might also find applications beyond Superfluids in systems described by more than one fluid component.
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A new self-consistent approach of quantum turbulence in superfluid helium
The European Physical Journal Plus, 2020Co-Authors: Luca Galantucci, Carlo F. Barenghi, Andrew W. Baggaley, Giorgio KrstulovicAbstract:We present the Fully cOUpled loCAl model of sUperfLuid Turbulence (FOUCAULT) that describes the dynamics of finite temperature Superfluids. The superfluid component is described by the vortex filament method while the normal fluid is governed by a modified Navier–Stokes equation. The superfluid vortex lines and normal fluid components are fully coupled in a self-consistent manner by the friction force, which induces local disturbances in the normal fluid in the vicinity of vortex lines. The main focus of this work is the numerical scheme for distributing the friction force to the mesh points where the normal fluid is defined (stemming from recent advances in the study of the interaction between a classical viscous fluid and small active particles) and for evaluating the velocity of the normal fluid on the Lagrangian discretisation points along the vortex lines. In particular, we show that if this numerical scheme is not careful enough, spurious results may occur. The new scheme which we propose to overcome these difficulties is based on physical principles. Finally, we apply the new method to the problem of the motion of a superfluid vortex ring in a stationary normal fluid and in a turbulent normal fluid.
Carlos Hoyos - One of the best experts on this subject based on the ideXlab platform.
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effective theory of two dimensional chiral Superfluids gauge duality and newton cartan formulation
Physical Review B, 2015Co-Authors: Sergej Moroz, Carlos HoyosAbstract:We present a theory of Galilean-invariant conventional and chiral $p_x \pm ip_y$ fermionic Superfluids at zero temperature in two spatial dimensions in terms of a dual gauge theory. Our formulation is general coordinate invariant. The parity-violating effects are encoded in the Wen-Zee term that gives rise to the Hall viscosity and edge current. We show that the relativistic superfluid with the Euler current reduces to the chiral superfluid in the limit $c\to\infty$. Using Newton-Cartan geometry we construct the covariant formulation of the effective theory and calculate the energy current.
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effective theory of two dimensional chiral Superfluids gauge duality and newton cartan formulation
Physical Review B, 2015Co-Authors: Sergej Moroz, Carlos HoyosAbstract:We present a theory of Galilean-invariant conventional and chiral ${p}_{x}\ifmmode\pm\else\textpm\fi{}i{p}_{y}$ fermionic Superfluids at zero temperature in two spatial dimensions in terms of a dual gauge theory. Our formulation is general coordinate invariant. The parity-violating effects are encoded in the Wen-Zee term that gives rise to the Hall viscosity and edge current. We show that the relativistic superfluid with the Euler current reduces to the chiral superfluid in the limit $c\ensuremath{\rightarrow}\ensuremath{\infty}$. Using Newton-Cartan geometry, we construct the covariant formulation of the effective theory and calculate the energy current.
Juan Ignacio Polanco - One of the best experts on this subject based on the ideXlab platform.
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Counterflow-Induced Inverse Energy Cascade in Three-Dimensional Superfluid Turbulence
Physical Review Letters, 2020Co-Authors: Juan Ignacio Polanco, Giorgio KrstulovicAbstract:Finite-temperature quantum turbulence is often described in terms of two immiscible fluids that can flow with a nonzero-mean relative velocity. Such out-of-equilibrium state is known as counterflow superfluid turbulence. We report here the emergence of a counterflow-induced inverse energy cascade in three-dimensional superfluid flows by performing extensive numerical simulations of the Hall-Vinen-Bekarevich-Khalatnikov model. As the intensity of the mean counterflow is increased, an abrupt transition, from a fully three-dimensional turbulent flow to a quasi-two-dimensional system exhibiting a split cascade, is observed. The findings of this work could motivate new experimental settings to study quasi-two-dimensional superfluid turbulence in the bulk of three-dimensional experiments. They might also find applications beyond Superfluids in systems described by more than one fluid component.
