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Wolfgang Ketterle - One of the best experts on this subject based on the ideXlab platform.
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coreless vortex formation in a spinor bose einstein Condensate
Physical Review Letters, 2003Co-Authors: Aaron Leanhardt, Yongil Shin, David Kielpinski, D E Pritchard, Wolfgang KetterleAbstract:: Coreless vortices were phase imprinted in a spinor Bose-Einstein Condensate. The three-component order parameter of F=1 sodium Condensates held in a Ioffe-Pritchard magnetic trap was manipulated by adiabatically reducing the magnetic bias field along the trap axis to zero. This distributed the Condensate population across its three spin states and created a spin texture. Each spin state acquired a different phase winding which caused the spin components to separate radially.
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transport of bose einstein Condensates with optical tweezers
Physical Review Letters, 2001Co-Authors: T L Gustavson, A P Chikkatur, Aaron Leanhardt, A Gorlitz, Subhadeep Gupta, David E Pritchard, Wolfgang KetterleAbstract:We have transported gaseous Bose-Einstein Condensates over distances up to 44 cm. This was accomplished by trapping the Condensate in the focus of an infrared laser and translating the location of the laser focus with controlled acceleration. Condensates of order ${10}^{6}$ atoms were moved into an auxiliary chamber and loaded into a magnetic trap formed by a Z-shaped wire. This transport technique avoids the optical and mechanical access constraints of conventional Condensate experiments and creates many new scientific opportunities.
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SPINOR CondensateS AND LIGHT SCATTERING FROM BOSE-EINSTEIN CondensateS
arXiv: Soft Condensed Matter, 2000Co-Authors: Dan M. Stamper-kurn, Wolfgang KetterleAbstract:These notes discuss two aspects of the physics of atomic Bose-Einstein Condensates: optical properties and spinor Condensates. The first topic includes light scattering experiments which probe the excitations of a Condensate in both the free-particle and phonon regime. At higher light intensity, a new form of superradiance and phase-coherent matter wave amplification were observed. We also discuss properties of spinor Condensates and describe studies of ground-state spin domain structures and dynamical studies which revealed metastable excited states and quantum tunneling.
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observation of metastable states in spinor bose einstein Condensates
Physical Review Letters, 1999Co-Authors: H. J. Miesner, A P Chikkatur, Dan Stamperkurn, J Stenger, S Inouye, Wolfgang KetterleAbstract:Bose-Einstein Condensates have been prepared in long-lived metastable excited states. Two complementary types of metastable states were observed. The first is due to the immiscibility of multiple components in the Condensate, and the second to local suppression of spin-relaxation collisions. Relaxation via recondensation of noncondensed atoms, spin relaxation, and quantum tunneling was observed. These experiments were done with F › 1 spinor Bose-Einstein Condensates of sodium confined in an optical dipole trap. [S0031-9007(99)08657-3] PACS numbers: 03.75.Fi, 05.30.Jp, 64.60.My, 67.40.Fd Metastable states of matter, excited states which relax only slowly to the ground state, are commonly encountered. This slow relaxation often arises from the presence of free-energy barriers that prevent a system from directly evolving toward its ground state; if the thermal energy to overcome this barrier is not available, the metastable state may be long lived. Many properties of Bose-Einstein Condensates in dilute atomic gases [1 ‐ 4] arise from metastability; indeed, such Condensates are themselves metastable, since the true equilibrium state is a solid at these low temperatures. Bose-Einstein Condensates in gases with attractive interactions [3] are metastable against collapse due to a kinetic energy barrier [5]. The persistence of rotations in Condensates with repulsive interactions hinges on whether
Elhameh Narimani - One of the best experts on this subject based on the ideXlab platform.
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Simulation of hydrodesulfurization unit for natural gas Condensate with high sulfur content
Applied Petrochemical Research, 2016Co-Authors: Javad Alaei Kadijani, Elhameh NarimaniAbstract:The natural gas Condensates are composed of various components of hydrocarbons and some contaminants such as hydrogen sulfide, thiols (mercaptans), and aromatics. Thus, the natural gas Condensates could be considered as a fuel resource. This study concerned the simulation of an Ultra-Deep Hydrodesulfurization (UDHDS) unit plus a distillation section to treat a combination of gas Condensate and disulfide oils (DSO) and produce clean fuel cuts. Gas Condensate of South Pars field of Iran with high sulfur content was applied to obtain clean fuel cuts. In order to reduce the sulfur content of this stream to less than 10 ppmw as sulfur, a UDHDS unit was simulated using Aspen HYSYS software package. The clean gas Condensate leaving the UDHDS unit (with sulfur content
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simulation of hydrodesulfurization unit for natural gas Condensate with high sulfur content
Applied Petrochemical Research, 2016Co-Authors: Javad Alaei Kadijani, Elhameh NarimaniAbstract:The natural gas Condensates are composed of various components of hydrocarbons and some contaminants such as hydrogen sulfide, thiols (mercaptans), and aromatics. Thus, the natural gas Condensates could be considered as a fuel resource. This study concerned the simulation of an Ultra-Deep Hydrodesulfurization (UDHDS) unit plus a distillation section to treat a combination of gas Condensate and disulfide oils (DSO) and produce clean fuel cuts. Gas Condensate of South Pars field of Iran with high sulfur content was applied to obtain clean fuel cuts. In order to reduce the sulfur content of this stream to less than 10 ppmw as sulfur, a UDHDS unit was simulated using Aspen HYSYS software package. The clean gas Condensate leaving the UDHDS unit (with sulfur content <10 ppmw) contains complex mixtures of hydrocarbon components called petroleum cuts which are identified by their boiling points ranges. To obtain the narrow fractions of butane, light naphtha, heavy naphtha, kerosene, and gasoil, a fractional distillation system was simulated. The simulation results revealed that the top products of distillation column, namely butane, light naphtha, and heavy naphtha were sulfur free and the sulfur contents of kerosene and gasoil cuts were 12 and 27 ppmw as sulfur, respectively.
Aaron Leanhardt - One of the best experts on this subject based on the ideXlab platform.
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coreless vortex formation in a spinor bose einstein Condensate
Physical Review Letters, 2003Co-Authors: Aaron Leanhardt, Yongil Shin, David Kielpinski, D E Pritchard, Wolfgang KetterleAbstract:: Coreless vortices were phase imprinted in a spinor Bose-Einstein Condensate. The three-component order parameter of F=1 sodium Condensates held in a Ioffe-Pritchard magnetic trap was manipulated by adiabatically reducing the magnetic bias field along the trap axis to zero. This distributed the Condensate population across its three spin states and created a spin texture. Each spin state acquired a different phase winding which caused the spin components to separate radially.
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transport of bose einstein Condensates with optical tweezers
Physical Review Letters, 2001Co-Authors: T L Gustavson, A P Chikkatur, Aaron Leanhardt, A Gorlitz, Subhadeep Gupta, David E Pritchard, Wolfgang KetterleAbstract:We have transported gaseous Bose-Einstein Condensates over distances up to 44 cm. This was accomplished by trapping the Condensate in the focus of an infrared laser and translating the location of the laser focus with controlled acceleration. Condensates of order ${10}^{6}$ atoms were moved into an auxiliary chamber and loaded into a magnetic trap formed by a Z-shaped wire. This transport technique avoids the optical and mechanical access constraints of conventional Condensate experiments and creates many new scientific opportunities.
Natalia G Berloff - One of the best experts on this subject based on the ideXlab platform.
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nonresonant optical control of a spinor polariton Condensate
Physical Review B, 2016Co-Authors: Alexis Askitopoulos, Kirill P Kalinin, Timothy Chi Hin Liew, Pasquale Cilibrizzi, Z Hatzopoulos, P G Savvidis, Natalia G BerloffAbstract:We investigate the spin dynamics of polariton Condensates spatially separated from and effectively confined by the pumping exciton reservoir. We obtain a strong correlation between the ellipticity of the non-resonant optical pump and the degree of circular polarisation (DCP) of the Condensate at the onset of condensation. With increasing excitation density we observe a reversal of the DCP. The spin dynamics of the trapped Condensate are described within the framework of the spinor complex Ginzburg-Landau equations in the Josephson regime, where the dynamics of the system are reduced to a current-driven Josephson junction. We show that the observed spin reversal is due to the interplay between an internal Josephson coupling effect and the detuning of the two projections of the spinor Condensate via transition from a synchronised to a desynchronised regime. These results suggest that spinor polariton Condensates can be controlled by tuning the non-resonant excitation density offering applications in electrically pumped polariton spin switches.
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spatially non uniform ground state and quantized vortices in a two component bose einstein Condensate of magnons
Scientific Reports, 2012Co-Authors: Patrik Nowikboltyk, Vladislav E. Demidov, Natalia G Berloff, O Dzyapko, Sergej O. DemokritovAbstract:A gas of magnons in magnetic films differs from all other known systems demonstrating Bose-Einstein condensation (BEC), since it possesses two energetically degenerate lowest-energy quantum states with non-zero wave vectors ±kBEC. Therefore, BEC in this system results in a spontaneously formed two-component Bose-Einstein Condensate described by a linear combination of two spatially non-uniform wave-functions ∝exp(±ikBECz), while Condensates found in other physical systems are characterized by spatially uniform wave-functions. Here we report a study of BEC of magnons with sub-micrometer spatial resolution. We experimentally confirm the existence of the two wave-functions and show that their interference results in a non-uniform ground state of the Condensate with the density oscillating in space. Additionally, we observe stable topological defects in the Condensate. By comparing the experimental results with predictions of a theoretical model based on the Ginzburg-Landau equation, we identify these defects as quantized vortices.
R G Hulet - One of the best experts on this subject based on the ideXlab platform.
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formation and propagation of matter wave soliton trains
Nature, 2002Co-Authors: K E Strecker, Guthrie B Partridge, A G Truscott, R G HuletAbstract:Attraction between the atoms of a Bose–Einstein Condensate renders it unstable to collapse, although a Condensate with a limited number of atoms1 can be stabilized2 by confinement in an atom trap. However, beyond this number the Condensate collapses3,4,5. Condensates constrained to one-dimensional motion with attractive interactions are predicted to form stable solitons, in which the attractive forces exactly compensate for wave-packet dispersion1. Here we report the formation of bright solitons of 7Li atoms in a quasi-one-dimensional optical trap, by magnetically tuning the interactions in a stable Bose–Einstein Condensate from repulsive to attractive. The solitons are set in motion by offsetting the optical potential, and are observed to propagate in the potential for many oscillatory cycles without spreading. We observe a soliton train, containing many solitons; repulsive interactions between neighbouring solitons are inferred from their motion.