Giant vortices of controlled multiplicity in polariton lattices
Wolfgang Langbein2017, arXiv: Mesoscale and Nanoscale Physics
Sign up for access to the world's latest research
checkGet notified about relevant papers
checkSave papers to use in your research
checkJoin the discussion with peers
checkTrack your impact
Abstract
Strongly localized vorticity is a key ingredient of a broad variety of fluid phenomena, and its quantized version is considered to be the hallmark of superfluidity. Flows that correspond to vortices of a large topological charge, termed "giant vortices", are notoriously difficult to realise and even when externally imprinted, they are unstable, breaking into many vortices of a single charge. In spite of many theoretical proposals on the formation and stabilisation of giant vortices in ultra cold atomic Bose-Einstein condensates and other superfluid systems, their experimental realisation remains illusive. Polariton condensates stand out from other superfluid systems due to their particularly strong interparticle interactions combined with their non-equilibrium nature, and as such provide an alternative test-bed for the study of non-trivial vortices. Here, we show that by injecting an odd number of polariton condensates at the vertices of a regular polygon and imposing frus...
Related papers
Geometric frustration in polygons of polariton condensates creating vortices of varying topological charge
Nature Communications, 2021
Vorticity is a key ingredient to a broad variety of fluid phenomena, and its quantised version is considered to be the hallmark of superfluidity. Circulating flows that correspond to vortices of a large topological charge, termed giant vortices, are notoriously difficult to realise and even when externally imprinted, they are unstable, breaking into many vortices of a single charge. In spite of many theoretical proposals on the formation and stabilisation of giant vortices in ultra-cold atomic Bose-Einstein condensates and other superfluid systems, their experimental realisation remains elusive. Polariton condensates stand out from other superfluid systems due to their particularly strong interparticle interactions combined with their non-equilibrium nature, and as such provide an alternative testbed for the study of vortices. Here, we non-resonantly excite an odd number of polariton condensates at the vertices of a regular polygon and we observe the formation of a stable discrete v...
Coreless vorticity in multicomponent Bose and Fermi superfluids
Physical Review A, 2010
We consider quantized vortices in two-component Bose-Einstein condensates and three-component Fermi gases with attractive interactions. In these systems, the vortex core can be either empty (normal in the fermion case) or filled with another superfluid. We determine critical values of the parameters -chemical potentials, scattering lengths and, for Fermi gases, temperature -at which a phase transition between the two types of vortices occurs. Population imbalance can lead to superfluid core (coreless) vorticity in multicomponent superfluids which otherwise support only usual vortices. For multicomponent Fermi gases, we construct the phase diagram including regions of coreless vorticity. We extend our results to trapped bosons and fermions using an appropriate local approximation, which goes beyond the usual Thomas-Fermi approximation for trapped bosons.
Probing the Dynamics of Spontaneous Quantum Vortices in Polariton Superfluids
Physical Review Letters, 2011
The experimental investigation of spontaneously created vortices is of utmost importance for the understanding of quantum phase transitions towards a superfluid phase, especially for two-dimensional systems that are expected to be governed by the Berezinski-Kosterlitz-Thouless physics. By means of time-resolved near-field interferometry we track the path of such vortices, created at random locations in an exciton-polariton condensate under pulsed nonresonant excitation, to their final pinning positions imposed by the stationary disorder. We formulate a theoretical model that successfully reproduces the experimental observations.
A tale of two distributions: from few to many vortices in quasi-two-dimensional Bose-Einstein condensates
Proceedings. Mathematical, physical, and engineering sciences / the Royal Society, 2014
Motivated by the recent successes of particle models in capturing the precession and interactions of vortex structures in quasi-two-dimensional Bose-Einstein condensates, we revisit the relevant systems of ordinary differential equations. We consider the number of vortices N as a parameter and explore the prototypical configurations ('ground states') that arise in the case of few or many vortices. In the case of few vortices, we modify the classical result illustrating that vortex polygons in the form of a ring are unstable for N≥7. Additionally, we reconcile this modification with the recent identification of symmetry-breaking bifurcations for the cases of N=2,…,5. We also briefly discuss the case of a ring of vortices surrounding a central vortex (so-called N+1 configuration). We finally examine the opposite limit of large N and illustrate how a coarse-graining, continuum approach enables the accurate identification of the radial distribution of vortices in that limit.
Bound vortex states and exotic lattices in multi-component Bose-Einstein condensates: The role of vortex-vortex interaction
We numerically study the vortex-vortex interaction in multi-component homogeneous Bose-Einstein condensates within the realm of the Gross-Pitaevskii theory. We provide strong evidences that pairwise vortex interaction captures the underlying mechanisms which determine the geometric configuration of the vortices, such as different lattices in many-vortex states, as well as the bound vortex states with two (dimer) or three (trimer) vortices. Specifically, we discuss and apply our theoretical approach to investigate intra-and inter-component vortex-vortex interactions in two-and three-component Bose-Einstein condensates, thereby shedding light on the formation of the exotic vortex configurations. These results correlate with current experimental efforts in multi-component Bose-Einstein condensates, and the understanding of the role of vortex interactions in multiband superconductors.
Quantum Vortices of Superfluidity
"It is indeed still a major open question the degree of superfluid character in the newly discovered supersolid states, and this question remains still very little studied today." [35] Scientists have shown how an optical chip can simulate the motion of atoms within molecules at the quantum level, which could lead to better ways of creating chemicals for use as pharmaceuticals. [34]
Interactions of vortices with rarefaction solitary waves in a Bose-Einstein condensate and their role in the decay of superfluid turbulence
Physical Review A, 2004
There are several ways to create the vorticity-free solitary waves-rarefaction pulses-in condensates: by the process of strongly nonequilibrium condensate formation in a weakly interacting Bose gas, by creating local depletion of the condensate density by a laser beam, and by moving a small object with supercritical velocities. Perturbations created by such waves colliding with vortices are studied in the context of the Gross-Pitaevskii model. We find that the effect of the interactions consists of two competing mechanisms: the creation of vortex line as rarefaction waves acquire circulation in a vicinity of a vortex core and the loss of the vortex line to sound due to Kelvin waves that are generated on vortex lines by rarefaction pulses. When a vortex ring collides with a rarefaction wave, the ring either stabilises to a smaller ring after emitting sound through Kelvin wave radiation or the entire energy of the vortex ring is lost to sound if the radius of the ring is of the order of the healing length. We show that during the time evolution of a tangle of vortices, the interactions with rarefaction pulses provide an important dissipation mechanism enhancing the decay of superfluid turbulence.
Vortex lattices in three-component Bose-Einstein condensates under rotation: simulating colorful vortex lattices in a color superconductor
2013
We study vortex lattices in three-component BECs under rotation, where three kinds of fractional vortices winding one of three components are present. Unlike the cases of two-component BECs where the phases of square and triangular lattices are present depending on the intercomponent coupling constant and the rotation speed, we find triangular ordered "colorful" vortex lattices where three kind of fractional vortices are placed in order without defects, in all parameter region where the inter-component coupling g is less than the intra-component coupling g. When g > g on the other hand, we find the phase separation; In a region where one component is present, the other two components must vanish, where we find ghost vortices in these two components whose positions are separated. In the boundary g = g , the accidental U (3) symmetry is present, in which case two vortices in different components are close to each other in some regions. arXiv:1304.4375v1 [cond-mat.quant-gas]
Room-temperature superfluidity in a polariton condensate
Nature Physics
Superfluidity-the suppression of scattering in a quantum fluid at velocities below a critical value-is one of the most striking manifestations of the collective behaviour typical of Bose-Einstein condensates. 1 This phenomenon, akin to superconductivity in metals, has until now only been observed at prohibitively low cryogenic temperatures.
Vortex lattices in Bose-Einstein condensates with dipolar interactions beyond the weak-interaction limit
Physical Review A, 2007
We study the ground states of rotating atomic Bose-Einstein condensates with dipolar interactions. We present the results of numerical studies on a periodic geometry which show vortex lattice ground states of various symmetries: triangular and square vortex lattices, "stripe crystal" and "bubble crystal". We present the phase diagram (for systems with a large number of vortices) as a function of the ratio of dipolar to contact interactions and of the chemical potential. We discuss the experimental requirements for observing transitions between vortex lattice groundstates via dipolar interactions. We finally investigate the stability of mean-field supersolid phases of a quasi-2D non-rotating Bose gas with dipolar interactions.
Related topics
Related papers
Quantized Vortices in an Imperfect Bose Gas and the Breakdown of Superfluidity in Liquid Helium II
Physical Review
The energy and momentum associated with vortex formation in an imperfect Bose gas have been computed quantum mechanically. In the computation, explicit account is taken of the boundary condition to be satisfied by the wave function at the walls surrounding the Quid. Numerical estimates of the critical velocity obtained thereby throw considerable light on the question of the most favorable location (relative to the walls) for the formation of the vortex. It is concluded that the optimum location for this formation could be well within the Quidsignificantly away from the walls. I. INTRODUCTION HE existence of quantized vortex rings as a mode of excitation in liquid helium II and their relevance to the phenomenon of breakdown of superfluidity are by now well established. ' ' Accordingly, a number
VORTICES IN BOSE–EINSTEIN CONDENSATES: SOME RECENT DEVELOPMENTS
Modern Physics Letters B, 2004
In this brief review we summarize a number of recent developments in the study of vortices in Bose-Einstein condensates, a topic of considerable theoretical and experimental interest in the past few years. We examine the generation of vortices by means of phase imprinting, as well as via dynamical instabilities. Their stability is subsequently examined in the presence of purely magnetic trapping, and in the combined presence of magnetic and optical trapping. We then study pairs of vortices and their interactions, illustrating a reduced description in terms of ordinary differential equations for the vortex centers. In the realm of two vortices we also consider the existence of stable dipole clusters for two-component condensates. Last but not least, we discuss mesoscopic patterns formed by vortices, the so-called vortex lattices and analyze some of their intriguing dynamical features. A number of interesting future directions are highlighted.
Quantized vortices in an exciton–polariton condensate
Nature Physics, 2008
One of the most striking quantum effects in a low temperature interacting Bose gas is superfluidity. First observed in liquid He, this phenomenon has been intensively studied in a variety of systems for its amazing features such as the persistence of superflows and the quantization of the angular momentum of vortices . The achievement of Bose-Einstein condensation (BEC) in dilute atomic gases provided an exceptional opportunity to observe and study superfluidity in an extremely clean and controlled environment. In the solid state, Bose-Einstein condensation of exciton polaritons has now been reported several times. Polaritons are strongly interacting light-matter quasi-particles, naturally occurring in semiconductor microcavities in the strong coupling regime and constitute a very interesting example of composite bosons. Even though pioneering experiments have recently addressed the propagation of a fluid of coherent polaritons , still no conclusive 4 1 2 3,4,5,6 7
Creation and robustness of quantized vortices in a dipolar supersolid when crossing the superfluid-to-supersolid transition
Physical Review A
Experiments on dipolar Bose-Einstein condensates have recently reported the observation of supersolidity. Although quantized vortices constitute a key probe of superfluidity, their observability in dipolar supersolids is largely prevented by the strong density depletion caused by the formation of droplets. We present a novel approach to the nucleation of vortices and their observation, based on the quenching of the s-wave scattering length across the superfluid-supersolid transition. Starting from a slowly rotating, vortex-free, configuration in the superfluid phase, we predict vortex nucleation as the system enters the supersolid phase, due to the strong reduction of the critical angular velocity in the supersolid. Once a vortex is created, we show that it is robustly preserved when the condensate is brought back to the superfluid phase, where it may be readily observed.
Structural change of vortex patterns in anisotropic Bose-Einstein condensates
Physical Review A, 2011
We study the changes in the spatial distribution of vortices in a rotating Bose-Einstein condensate due to an increasing anisotropy of the trapping potential. Once the rotational symmetry is broken, we find that the vortex system undergoes a rich variety of structural changes, including the formation of zig-zag and linear configurations. These spatial re-arrangements are well signaled by the change in the behavior of the vortex-pattern eigenmodes against the anisotropy parameter. The existence of such structural changes opens up possibilities for the coherent exploitation of effective many-body systems based on vortex patterns.
Massive Quantum Vortices in Superfluids
Journal of physics, 2023
We consider the dynamical properties of quantum vortices with filled massive cores, hence the term "massive vortices". While the motion of massless vortices is described by firstorder motion equations, the inclusion of core mass introduces a second-order time derivative in the motion equations and thus doubles the number of independent dynamical variables needed to describe the vortex. The simplest possible system where this physics is present, i.e. a single massive vortex in a circular domain, is thoroughly discussed. We point out that a massive vortex can exhibit various dynamical regimes, as opposed to its massless counterpart, which can only precess at a constant rate. The predictions of our analytical model are validated by means of numerical simulations of coupled Gross-Pitaevskii equations, which indeed display the signature of the core inertial mass. Eventually, we discuss a nice formal analogy between the motion of massive vortices and that of massive charges in two-dimensional domains pierced by magnetic fields.
Giant vortex clusters in a two-dimensional quantum fluid
Science
Adding energy to a system through transient stirring usually leads to more disorder. In contrast, point-like vortices in a bounded two-dimensional fluid are predicted to reorder above a certain energy, forming persistent vortex clusters. In this study, we experimentally realize these vortex clusters in a planar superfluid: a 87Rb Bose-Einstein condensate confined to an elliptical geometry. We demonstrate that the clusters persist for long time periods, maintaining the superfluid system in a high-energy state far from global equilibrium. Our experiments explore a regime of vortex matter at negative absolute temperatures and have relevance for the dynamics of topological defects, two-dimensional turbulence, and systems such as helium films, nonlinear optical materials, fermion superfluids, and quark-gluon plasmas.
Superfluidity and collective oscillations of trapped Bose-Einstein condensates in a periodical potential
The European Physical Journal D, 2012
Based on a unified theoretical treatment of the 1D Bogoliubov-de Genes equations, the superfluidity phenomenon of the Bose-Einstein condensates (BEC) loaded into trapped optical lattice is studied. Within the perturbation regime, an all-analytical framework is presented enabling a straightforward phenomenological mapping of the collective excitation and oscillation character of a trapped BEC where the available experimental configurations also fit.
Loading Preview
Sorry, preview is currently unavailable. You can download the paper by clicking the button above.