BREAKDOWN OF VORTEX-FREE STATE IN BEC BY VORTEX-ANTIVORTEX PAIRS W. V. Pogosov and K. Machida Department of Physics, Okayama University, Japan.

Презентация:



Advertisements
Похожие презентации
VORTEX MATTER IN ATOMIC BOSE-EINSTEIN CONDENSATES W. V. Pogosov, Institut des NanoSciences de Paris, Universite Paris VI – Pierre et Marie Curie, Paris;
Advertisements

THERMAL MELTING OF VORTEX MOLECULES IN 2D BOSE-EINSTEIN CONDENSATES W. Pogosov and K. Machida Okayama University, Japan 1. Motivation 2. Model 3. Intershell.
VORTEX PHASES IN PERIODIC PLUS RANDOM PINNING POTENTIAL Walter Pogosov, Institute for Theoretical and Applied Electrodynamics, Russian Academy of Sciences,
7/23/20151 Relativistic electron beam transport simulation models German Kurevlev.
Michael Marchenko. In mathematics, a sequence is an ordered list of objects (or events). Like a set, it contains members (also called elements, or terms),
Variational calculations of vortex structures in bulk and mesoscopic superconductors Walter Pogosov, Laboratorium voor Vaste-Stoffysica en Magnetisme,
Antimatter In particle physics, antimatter is material composed of antiparticles, which have the same mass as particles of ordinary matter but have opposite.
Vortex lattice in presence of weak periodic pinning potential W. V. Pogosov and V. V. Moshchalkov Laboratorium voor Vaste-Stoffysica en Magnetisme, K.
MATHEMATICAL MODEL OF ICE SHEET DEFORMATION CAUSED BY SUBMARINE MOTION V. M. Kozin, V. L. Zemlak, S. D. Chizhiumov Shipbuilding Department, State Technical.
PROJECT Ecological Problems In the world. I. Introduction The theme of our report is Global ecological problems. We would like to tell you about the most.
Schrodingers Equation for Three Dimensions. QM in Three Dimensions The one dimensional case was good for illustrating basic features such as quantization.
Diffraction and Interference. Interference and Diffraction Distinguish Waves from Particles O The key to understanding why light behaves like waves is.
S12-1 NAS122, Section 12, August 2005 Copyright 2005 MSC.Software Corporation SECTION 12 RESIDUAL VECTOR METHOD.
Welcome to…. YOUR FIRST PART – START TO FINISH 2.
The category of mood. The category of mood is an explicit verbal category expressing the relation of the action denoted by the predicate to reality as.
By Intersil Corporation. The ICL8038 waveform generator is a monolithic integrated circuit capable of producing high accuracy sine, square, triangular,
Special relativity. Special relativity (SR, also known as the special theory of relativity or STR) is the physical theory of measurement in an inertial.
Time-Series Analysis and Forecasting – Part IV To read at home.
E = mc2 Disproved Einstein's Relativity WALTER ORLOV.
© 2006 Cisco Systems, Inc. All rights reserved. MPLS v MPLS Concepts Introducing MPLS Labels and Label Stacks.
Транксрипт:

BREAKDOWN OF VORTEX-FREE STATE IN BEC BY VORTEX-ANTIVORTEX PAIRS W. V. Pogosov and K. Machida Department of Physics, Okayama University, Japan

1. Introduction 2. Stability of the nonvortex state 3. Penetration of topological defects 4. Summary Outlook

Introduction London model in Thomas-Fermi regime Disadvantages: -in reality, there is no TF boundary. How vortices nucleate? -strong gradients of the order parameter Linear analysis; surface modes Disadvantage: -No vortices, only stability of axially-symmetric nonvortex state Numerical simulations Disadvantages: -Transition can be very sharp -Artificial boundary for the system

The aim of the present work: Where and how vortices nucleate? What is the role of surface modes and Landau instability in vortex nucleation?

The energy in dimensionless form: Gas parameter:

Method Nonvortex state: Stability of the nonvortex state

Normalization condition:

Linear analysis around a local minimum The energy: F is diagonal for the vortex-free phase Stability criteria:

Landau criterion:

Penetration of topological defects In the vicinity of the instability point, the order parameter can be represented as

-The same mechanism for vortex penetration is realized for the range of p corresponding to the generation of excitations with l inst = 5

Mechanism of vortex nucleation at even l inst (l inst = 4, 6) -Nonvortex axially-symmetric state becomes unstable with respect to the generation of excitations with l inst -With increasing of the rotation frequency, the number of particles condensed in the state with l inst increases. -Just before the formation of l inst vortices, other harmonics of ψ appear: l = 3 for l inst = 6; l = 2 for l inst = 4 at p > 1.5; l = 1 and 2 for l inst = 4 at p < 1.5; -Final state contains l inst /2 or l inst /4 vortices in the inner part of the cloud

The case of finite-size cloud Boundary condition -When R b > 2-3 R TF, vortex-antivortex pairs nucleate. With increasing of the rotation frequency, antivortices leave the system. -When R b ~ R TF, vortices penetrate from the edge. No antivortices.

3D case -Prediction: vortex loops nucleate instead of vortex-antivortex pairs -Bending of vortices in 3D case was observed in numerical simulations

- Topological defects in BEC nucleate via creation of vortex-antivortex pairs (2D) or vortex loops (3D). Vortices move to the inner part of the cloud and antivortices – in the opposite direction. - Vortices penetrate just above the Landau instability. This supports Anglins scenario (PRL 2001) - Vortex state in infinite BEC always consists of vortices and antivortices. Total topological charge is zero. Summary