The Experts below are selected from a list of 54885 Experts worldwide ranked by ideXlab platform
Chuanwei Zhang - One of the best experts on this subject based on the ideXlab platform.
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structured weyl points in spin orbit coupled fermionic Superfluids
Physical Review Letters, 2015Co-Authors: Fan Zhang, Chuanwei ZhangAbstract:We demonstrate that a Weyl point, widely examined in 3D Weyl semimetals and Superfluids, can develop a pair of nondegenerate gapless spheres. Such a bouquet of two spheres is characterized by three distinct topological invariants of manifolds with full energy gaps, i.e., the Chern number of a 0D point inside one developed sphere, the winding number of a 1D loop around the original Weyl point, and the Chern number of a 2D surface enclosing the whole bouquet. We show that such structured Weyl points can be realized in the Superfluid quasiparticle spectrum of a 3D degenerate Fermi gas subject to spin-orbit couplings and Zeeman fields, which supports Fulde-Ferrell Superfluids as the ground state.
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berezinskii kosterlitz thouless phase transition in 2d spin orbit coupled fulde ferrell Superfluids
Physical Review Letters, 2015Co-Authors: Chuanwei ZhangAbstract:The experimental observation of traditional Zeeman-field induced Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) Superfluids has been hindered by various challenges, in particular, the requirement of low dimensional systems. In 2D, finite temperature phase fluctuations lead to an extremely small Berezinskii-Kosterlitz-Thouless (BKT) transition temperature for FFLO Superfluids, raising serious concerns regarding their experimental observability. Recently, it was shown that FFLO Superfluids can be realized using a Rashba spin-orbit coupled Fermi gas subject to Zeeman fields, which may also support topological excitations such as Majorana fermions in 2D. Here we address the finite temperature BKT transition issue in this system, which may exhibit gapped, gapless, topological, and gapless topological FF phases. We find a large BKT transition temperature due to large effective Superfluid densities, making it possible to observe 2D FF Superfluids at finite temperature. In addition, we show that gapless FF Superfluids can be stable due to their positive Superfluid densities. These findings pave the way for the experimental observation of 2D gapped and gapless FF Superfluids and their associated topological excitations at finite temperature.
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structured weyl points in fulde ferrell Superfluids
arXiv: Quantum Gases, 2014Co-Authors: Fan Zhang, Chuanwei ZhangAbstract:We demonstrate that a Weyl point, widely examined in 3D Weyl semimetals and Superfluids, can develop a pair of non-degenerate gapless spheres. Such a {\em bouquet of two spheres} is characterized by {\em three distinct} topological invariants of manifolds with full energy gaps, i.e., the Chern number of a 0D point inside one developed sphere, the winding number of a 1D loop around the original Weyl point, and the Chern number of a 2D surface enclosing the whole bouquet. We show that such structured Weyl points can be realized in the Fulde-Ferrell Superfluid quasiparticle spectrum of a 3D degenerate Fermi gas subject to spin-orbit couplings and Zeeman fields.
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px ipy Superfluid from s wave interactions of fermionic cold atoms
Physical Review Letters, 2008Co-Authors: Chuanwei Zhang, Sumanta Tewari, Roman M Lutchyn, Das S SarmaAbstract:Two-dimensional (p(x)+ip(y)) Superfluids or superconductors offer a playground for studying intriguing physics such as quantum teleportation, non-Abelian statistics, and topological quantum computation. Creating such a Superfluid in cold fermionic atom optical traps using p-wave Feshbach resonance is turning out to be challenging. Here we propose a method to create a p(x)+ip(y) Superfluid directly from an s-wave interaction making use of a topological Berry phase, which can be artificially generated. We discuss ways to detect the spontaneous Hall mass current, which acts as a diagnostic for the chiral p-wave Superfluid.
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quantum computation using vortices and majorana zero modes of a px ipy Superfluid of fermionic cold atoms
Physical Review Letters, 2007Co-Authors: Sumanta Tewari, Chuanwei Zhang, Das S Sarma, Chetan Nayak, P ZollerAbstract:We propose to use the recently predicted two-dimensional "weak-pairing" px + ipy Superfluid state of fermionic cold atoms as a platform for topological quantum computation. In the core of a vortex, this state supports a zero-energy Majorana mode, which moves to finite energy in the corresponding topologically trivial "strong-pairing" state. By braiding vortices in the "weak-pairing" state, unitary quantum gates can be applied to the Hilbert space of Majorana zero modes. For readout of the topological qubits, we propose realistic schemes suitable for atomic Superfluids.
M Krusius - One of the best experts on this subject based on the ideXlab platform.
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kelvin helmholtz instability of ab interface in Superfluid he 3
Physical Review B, 2019Co-Authors: V B Eltsov, A Gordeev, M KrusiusAbstract:The Kelvin-Helmholtz instability is well-known in classical hydrodynamics, where it explains the sudden emergence of interfacial surface waves as a function of the velocity of flow parallel to the interface. It can be carried over to the inviscid two-fluid dynamics of Superfluids, to study different types of interfaces and phase boundaries in quantum fluids. We report measurements on the stability of the phase boundary separating the two bulk phases of Superfluid 3He in rotating flow, while the boundary is localized with the gradient of the magnetic field to a position perpendicular to the rotation axis. The results demonstrate that the classic stability condition, when modified for the Superfluid environment, is obeyed down to 0.4 Tc, if a large fraction of the magnetic polarization of the B-phase is attributed to a parabolic reduction of the interfacial surface tension with increasing magnetic field.
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quantum turbulence in Superfluids with wall clamped normal component
Proceedings of the National Academy of Sciences of the United States of America, 2014Co-Authors: V B Eltsov, R Hanninen, M KrusiusAbstract:In Fermi Superfluids, such as Superfluid 3He, the viscous normal component can be considered to be stationary with respect to the container. The normal component interacts with the Superfluid component via mutual friction, which damps the motion of quantized vortex lines and eventually couples the Superfluid component to the container. With decreasing temperature and mutual friction, the internal dynamics of the Superfluid component becomes more important compared with the damping and coupling effects from the normal component. As a result profound changes in Superfluid dynamics are observed: the temperature-dependent transition from laminar to turbulent vortex motion and the decoupling from the reference frame of the container at even lower temperatures.
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an intrinsic velocity independent criterion for Superfluid turbulence
Nature, 2003Co-Authors: Antti Finne, V B Eltsov, M Krusius, Tsunehiko Araki, Rob Blaauwgeers, N B Kopnin, L Skrbek, Makoto TsubotaAbstract:Hydrodynamic flow in classical and quantum fluids can be either laminar or turbulent. Vorticity in turbulent flow is often modelled with vortex filaments. While this represents an idealization in classical fluids, vortices are topologically stable quantized objects in Superfluids. Superfluid turbulence1 is therefore thought to be important for the understanding of turbulence more generally. The fermionic 3He Superfluids are attractive systems to study because their characteristics vary widely over the experimentally accessible temperature regime. Here we report nuclear magnetic resonance measurements and numerical simulations indicating the existence of sharp transition to turbulence in the B phase of Superfluid 3He. Above 0.60Tc (where Tc is the transition temperature for Superfluidity) the hydrodynamics are regular, while below this temperature we see turbulent behaviour. The transition is insensitive to the fluid velocity, in striking contrast to current textbook knowledge of turbulence2. Rather, it is controlled by an intrinsic parameter of the Superfluid: the mutual friction between the normal and Superfluid components of the flow, which causes damping of the vortex motion.
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shear flow and kelvin helmholtz instability in Superfluids
Physical Review Letters, 2002Co-Authors: Rob Blaauwgeers, V B Eltsov, M Krusius, Antti Finne, G Eska, R P Haley, J J Ruohio, L SkrbekAbstract:The first realization of instabilities in the shear flow between two Superfluids is examined. The interface separating the A and B phases of Superfluid 3He is magnetically stabilized. With uniform rotation we create a state with discontinuous tangential velocities at the interface, supported by the difference in quantized vorticity in the two phases. This state remains stable and nondissipative to high relative velocities, but finally undergoes an instability when an interfacial mode is excited and some vortices cross the phase boundary. The measured properties of the instability are consistent with the classic Kelvin-Helmholtz theory when modified for two-fluid hydrodynamics.
V B Eltsov - One of the best experts on this subject based on the ideXlab platform.
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exceeding the landau speed limit with topological bogoliubov fermi surfaces
Physical Review Research, 2020Co-Authors: G. E. Volovik, S Autti, J T Makinen, J Rysti, V V Zavjalov, V B EltsovAbstract:The authors show that topological Superfluid 3He can flow without friction in a phase which possesses a line of zero energy in the excitation spectrum, although the Landau's limit for superflow is zero. The flow expands the node line to a Fermi surface for Bogoliubov quasipartices, which is usually absent in Cooper-paired systems, but may appear in unconventional superconductors and Superfluids with certain broken symmetries.
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kelvin helmholtz instability of ab interface in Superfluid he 3
Physical Review B, 2019Co-Authors: V B Eltsov, A Gordeev, M KrusiusAbstract:The Kelvin-Helmholtz instability is well-known in classical hydrodynamics, where it explains the sudden emergence of interfacial surface waves as a function of the velocity of flow parallel to the interface. It can be carried over to the inviscid two-fluid dynamics of Superfluids, to study different types of interfaces and phase boundaries in quantum fluids. We report measurements on the stability of the phase boundary separating the two bulk phases of Superfluid 3He in rotating flow, while the boundary is localized with the gradient of the magnetic field to a position perpendicular to the rotation axis. The results demonstrate that the classic stability condition, when modified for the Superfluid environment, is obeyed down to 0.4 Tc, if a large fraction of the magnetic polarization of the B-phase is attributed to a parabolic reduction of the interfacial surface tension with increasing magnetic field.
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quantum turbulence in Superfluids with wall clamped normal component
Proceedings of the National Academy of Sciences of the United States of America, 2014Co-Authors: V B Eltsov, R Hanninen, M KrusiusAbstract:In Fermi Superfluids, such as Superfluid 3He, the viscous normal component can be considered to be stationary with respect to the container. The normal component interacts with the Superfluid component via mutual friction, which damps the motion of quantized vortex lines and eventually couples the Superfluid component to the container. With decreasing temperature and mutual friction, the internal dynamics of the Superfluid component becomes more important compared with the damping and coupling effects from the normal component. As a result profound changes in Superfluid dynamics are observed: the temperature-dependent transition from laminar to turbulent vortex motion and the decoupling from the reference frame of the container at even lower temperatures.
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an intrinsic velocity independent criterion for Superfluid turbulence
Nature, 2003Co-Authors: Antti Finne, V B Eltsov, M Krusius, Tsunehiko Araki, Rob Blaauwgeers, N B Kopnin, L Skrbek, Makoto TsubotaAbstract:Hydrodynamic flow in classical and quantum fluids can be either laminar or turbulent. Vorticity in turbulent flow is often modelled with vortex filaments. While this represents an idealization in classical fluids, vortices are topologically stable quantized objects in Superfluids. Superfluid turbulence1 is therefore thought to be important for the understanding of turbulence more generally. The fermionic 3He Superfluids are attractive systems to study because their characteristics vary widely over the experimentally accessible temperature regime. Here we report nuclear magnetic resonance measurements and numerical simulations indicating the existence of sharp transition to turbulence in the B phase of Superfluid 3He. Above 0.60Tc (where Tc is the transition temperature for Superfluidity) the hydrodynamics are regular, while below this temperature we see turbulent behaviour. The transition is insensitive to the fluid velocity, in striking contrast to current textbook knowledge of turbulence2. Rather, it is controlled by an intrinsic parameter of the Superfluid: the mutual friction between the normal and Superfluid components of the flow, which causes damping of the vortex motion.
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shear flow and kelvin helmholtz instability in Superfluids
Physical Review Letters, 2002Co-Authors: Rob Blaauwgeers, V B Eltsov, M Krusius, Antti Finne, G Eska, R P Haley, J J Ruohio, L SkrbekAbstract:The first realization of instabilities in the shear flow between two Superfluids is examined. The interface separating the A and B phases of Superfluid 3He is magnetically stabilized. With uniform rotation we create a state with discontinuous tangential velocities at the interface, supported by the difference in quantized vorticity in the two phases. This state remains stable and nondissipative to high relative velocities, but finally undergoes an instability when an interfacial mode is excited and some vortices cross the phase boundary. The measured properties of the instability are consistent with the classic Kelvin-Helmholtz theory when modified for two-fluid hydrodynamics.
Sumanta Tewari - One of the best experts on this subject based on the ideXlab platform.
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px ipy Superfluid from s wave interactions of fermionic cold atoms
Physical Review Letters, 2008Co-Authors: Chuanwei Zhang, Sumanta Tewari, Roman M Lutchyn, Das S SarmaAbstract:Two-dimensional (p(x)+ip(y)) Superfluids or superconductors offer a playground for studying intriguing physics such as quantum teleportation, non-Abelian statistics, and topological quantum computation. Creating such a Superfluid in cold fermionic atom optical traps using p-wave Feshbach resonance is turning out to be challenging. Here we propose a method to create a p(x)+ip(y) Superfluid directly from an s-wave interaction making use of a topological Berry phase, which can be artificially generated. We discuss ways to detect the spontaneous Hall mass current, which acts as a diagnostic for the chiral p-wave Superfluid.
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quantum computation using vortices and majorana zero modes of a px ipy Superfluid of fermionic cold atoms
Physical Review Letters, 2007Co-Authors: Sumanta Tewari, Chuanwei Zhang, Das S Sarma, Chetan Nayak, P ZollerAbstract:We propose to use the recently predicted two-dimensional "weak-pairing" px + ipy Superfluid state of fermionic cold atoms as a platform for topological quantum computation. In the core of a vortex, this state supports a zero-energy Majorana mode, which moves to finite energy in the corresponding topologically trivial "strong-pairing" state. By braiding vortices in the "weak-pairing" state, unitary quantum gates can be applied to the Hilbert space of Majorana zero modes. For readout of the topological qubits, we propose realistic schemes suitable for atomic Superfluids.
Hongbao Zhang - One of the best experts on this subject based on the ideXlab platform.
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generation of vortices and stabilization of vortex lattices in holographic Superfluids
Journal of High Energy Physics, 2020Co-Authors: Hongbao Zhang, Yu TianAbstract:Within the simplest holographic Superfluid model and without any ingredient put by hand, it is shown that vortices can be generated when the angular velocity of rotating Superfluids exceeds certain critical values, which can be precisely determined by linear perturbation analyses (quasi-normal modes of the bulk AdS black brane). These vortices appear at the edge of the Superfluid system first, and then automatically move into the bulk of the system, where they are eventually stabilized into certain vortex lattices. For the case of 18 vortices generated, we find (at least) five different patterns of the final lattices formed due to different initial perturbations, which can be compared to the known result for such lattices in weakly coupled Bose-Einstein condensates from free energy analyses.
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black and gray solitons in holographic Superfluids at zero temperature
Journal of High Energy Physics, 2019Co-Authors: Hongbao Zhang, Yu Tian, Meng Gao, Yuqiu JiaoAbstract:We construct gray soliton configurations, which move at constant speeds, in holographic Superfluids for the first time. Since there should be no dissipation for a moving soliton to exist, we use the simplest holographic Superfluid model at zero temperature, considering both the standard and alternative quantizations. For comparison purpose, we first investigate black solitons in the zero temperature holographic Superfluids, which are static configurations. Then we focus on the numerical construction of gray solitons under both quantizations, which interpolate between the (static) black solitons and sound waves (moving at the speed of sound). Interestingly, under the standard quantization, a peculiar oscillation of the soliton configurations is observed, very much resembling the Friedel oscillation in fermionic Superfluids at the BCS regime. Some implications and other aspects of the soliton configurations are also discussed.
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Note on Zero Temperature Holographic Superfluids
Classical and Quantum Gravity, 2016Co-Authors: Hongbao Zhang, Yu TianAbstract:In this note, we have addressed various issues on zero temperature holographic Superfluids. First, inspired by our numerical evidence for the equality between the Superfluid density and particle density, we provide an elegant analytic proof for this equality by a boost trick. Second, using not only the frequency domain analysis but also the time domain analysis from numerical relativity, we identify the hydrodynamic normal modes and calculate out the sound speed, which is shown to increase with the chemical potential and saturate to the value predicted by the conformal field theory in the large chemical potential limit. Third, the generic non-thermalization is demonstrated by the fully nonlinear time evolution from a non-equilibrium state for our zero temperature holographic Superfluid. Furthermore, a conserved Noether charge is proposed in support of this behavior.
