0000000000150211

AUTHOR

Mikio Nakahara

0000-0001-5219-9398

showing 3 related works from this author

Three-dimensional skyrmions in spin-2 Bose–Einstein condensates

2017

We introduce topologically stable three-dimensional skyrmions in the cyclic and biaxial nematic phases of a spin-2 Bose-Einstein condensate. These skyrmions exhibit exceptionally high mapping degrees resulting from the versatile symmetries of the corresponding order parameters. We show how these structures can be created in existing experimental setups and study their temporal evolution and lifetime by numerically solving the three-dimensional Gross-Pitaevskii equations for realistic parameter values. Although the biaxial nematic and cyclic phases are observed to be unstable against transition towards the ferromagnetic phase, their lifetimes are long enough for the skyrmions to be imprinted…

spinor condensateSUPERFLUID HE-3Angular momentumSYMMETRYFOS: Physical sciencesGeneral Physics and AstronomyBose-Einstein condensation114 Physical sciences01 natural sciencesInstability010305 fluids & plasmaslaw.inventionPHASESKNOTSlaw0103 physical sciencesField theory (psychology)magnetismikvanttifysiikka010306 general physicsVORTICESSpin-½Condensed Matter::Quantum GasesPhysicsBose–Einstein condensationBiaxial nematicCondensed matter physicsSkyrmionMONOPOLESCondensed Matter::Mesoscopic Systems and Quantum Hall EffectFIELD-THEORYSymmetry (physics)skyrmionQuantum Gases (cond-mat.quant-gas)Condensed Matter - Quantum GasesBose–Einstein condensateNew Journal of Physics
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Quantum knots in Bose-Einstein condensates created by counterdiabatic control

2017

We theoretically study the creation of knot structures in the polar phase of spin-1 BECs using the counterdiabatic protocol in an unusual fashion. We provide an analytic solution to the evolution of the external magnetic field that is used to imprint the knots. As confirmed by our simulations using the full three-dimensional spin-1 Gross-Pitaevskii equation, our method allows for the precise control of the Hopf charge as well as the creation time of the knots. The knots with Hopf charge exceeding unity display multiple nested Hopf links.

PhysicsCondensed Matter::Quantum GasesBose-Einstein condensateta114Condensed Matter::OtherFOS: Physical sciences01 natural sciencesMathematics::Geometric Topology010305 fluids & plasmaslaw.inventionMagnetic fieldknot structuresKnot (unit)Classical mechanicsQuantum Gases (cond-mat.quant-gas)law0103 physical sciencesPolarCondensed Matter - Quantum Gases010306 general physicsAnalytic solutionQuantumBose–Einstein condensatePhysical Review A
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Counterdiabatic vortex pump in spinor Bose-Einstein condensates

2017

Topological phase imprinting is a well-established technique for deterministic vortex creation in spinor Bose-Einstein condensates of alkali metal atoms. It was recently shown that counter-diabatic quantum control may accelerate vortex creation in comparison to the standard adiabatic protocol and suppress the atom loss due to nonadiabatic transitions. Here we apply this technique, assisted by an optical plug, for vortex pumping to theoretically show that sequential phase imprinting up to 20 cycles generates a vortex with a very large winding number. Our method significantly increases the fidelity of the pump for rapid pumping compared to the case without the counter-diabatic control, leadin…

Angular momentumalkali metalsQuantum controlFOS: Physical sciences01 natural sciencestopological phase imprinting010305 fluids & plasmaslaw.inventionlawQuantum mechanics0103 physical sciences010306 general physicsAdiabatic processPhysicsCondensed Matter::Quantum GasesSpinorta114Winding numberBose-Einstein condensatesVortexNumerical integrationvortex pumpsQuantum Gases (cond-mat.quant-gas)Condensed Matter - Quantum GasesBose–Einstein condensatealkalimetallitPhysical Review A
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