Brian P Anderson
- Associate Dean, Graduate Academic Affairs
- Professor, Optical Sciences
- Associate Professor, Physics
- Member of the Graduate Faculty
- American Physical Society, Spring 2014
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DissertationOPTI 920 (Fall 2021)
Quantum MechanicsOPTI 570 (Fall 2021)
DissertationOPTI 920 (Spring 2021)
Independent StudyPHYS 399 (Spring 2021)
ResearchOPTI 900 (Spring 2021)
DissertationOPTI 920 (Fall 2020)
Independent StudyPHYS 399 (Fall 2020)
Optical Physics Comp LabOPTI 571L (Fall 2020)
Quantum MechanicsOPTI 570 (Fall 2020)
ResearchOPTI 900 (Fall 2020)
DissertationOPTI 920 (Spring 2020)
Independent StudyPHYS 299 (Spring 2020)
Quantum MechanicsOPTI 345 (Spring 2020)
DissertationOPTI 920 (Fall 2019)
Independent StudyOPTI 599 (Fall 2019)
Independent StudyPHYS 299 (Fall 2019)
Optical Physics Comp LabOPTI 571L (Fall 2019)
Quantum MechanicsOPTI 570 (Fall 2019)
Atom OpticsOPTI 549 (Spring 2019)
DissertationOPTI 920 (Spring 2019)
Independent StudyOPTI 599 (Spring 2019)
Independent StudyPHYS 199 (Spring 2019)
DissertationOPTI 920 (Fall 2018)
Optical Physics Comp LabOPTI 571L (Fall 2018)
Quantum MechanicsOPTI 570 (Fall 2018)
DissertationOPTI 920 (Spring 2018)
DissertationOPTI 920 (Fall 2017)
Optical Physics Comp LabOPTI 571L (Fall 2017)
Quantum MechanicsOPTI 570 (Fall 2017)
Atom OpticsOPTI 549 (Spring 2017)
DissertationOPTI 920 (Spring 2017)
Directed Graduate ResearchOPTI 792 (Fall 2016)
DissertationOPTI 920 (Fall 2016)
Independent StudyOPTI 599 (Fall 2016)
Optical Physics Comp LabOPTI 571L (Fall 2016)
Quantum MechanicsOPTI 570 (Fall 2016)
Directed Graduate ResearchOPTI 792 (Spring 2016)
DissertationOPTI 920 (Spring 2016)
Independent StudyOPTI 599 (Spring 2016)
- Richardson, L., Hines, A., Schaffer, A., Anderson, B. P., & Guzman, F. (2020). Quantum hybrid optomechanical inertial sensing. Appl. Opt., 59(22), G160--G166.
- Cawte, M. M., Yu, X., Anderson, B. P., & Bradley, A. S. (2019). Snell's Law for a vortex dipole in a Bose-Einstein condensate. SCIPOST PHYSICS, 6(3).
- Kevrekidis, P. G., Wang, W., Theocharis, G., Frantzeskakis, D. J., Carretero-Gonzalez, R., & Anderson, B. P. (2019). Dynamics of interacting dark soliton stripes. PHYSICAL REVIEW A, 100(3).
- , M. M., , X. Y., , B. P., & , A. S. (2018). Snell's Law for a vortex dipole in a Bose-Einstein condensate.More infoA quantum vortex dipole, comprised of a closely bound pair of vortices ofequal strength with opposite circulation, is a spatially localized travellingexcitation of a planar superfluid that carries linear momentum, suggesting apossible analogy with ray optics. We investigate numerically and analyticallythe motion of a quantum vortex dipole incident upon a step-change in thebackground superfluid density of an otherwise uniform two-dimensionalBose-Einstein condensate. Due to the conservation of fluid momentum and energy,the incident and refracted angles of the dipole satisfy a relation analogous toSnell's law, when crossing the interface between regions of different density.The predictions of the analogue Snell's law relation are confirmed for a widerange of incident angles by systematic numerical simulations of theGross-Piteavskii equation. Near the critical angle for total internalreflection, we identify a regime of anomalous Snell's law behaviour where thefinite size of the dipole causes transient capture by the interface.Remarkably, despite the extra complexity of the surface interaction, theincoming and outgoing dipole paths obey Snell's law.[Journal_ref: ]
- Gertjerenken, B., Kevrekidis, P. G., Carretero-Gonzalez, R., & Anderson, B. P. (2016). Generating and manipulating quantized vortices on-demand in a Bose-Einstein condensate: A numerical study. PHYSICAL REVIEW A, 93(2).
- Samson, E. C., Wilson, K. E., Newman, Z. L., & Anderson, B. P. (2016). Deterministic creation, pinning, and manipulation of quantized vortices in a Bose-Einstein condensate. PHYSICAL REVIEW A, 93(2).
- Vocke, D., Wilson, K., Marino, F., Carusotto, I., Wright, E. M., Roger, T., Anderson, B. P., Ohberg, P., & Faccio, D. (2016). Role of geometry in the superfluid flow of nonlocal photon fluids. PHYSICAL REVIEW A, 94(1).
- Reeves, M. T., Billam, T. P., Anderson, B. P., & Bradley, A. S. (2015). Identifying a Superfluid Reynolds Number via Dynamical Similarity. PHYSICAL REVIEW LETTERS, 114(15).
- Wilson, K. E., Newman, Z. L., Lowney, J. D., & Anderson, B. P. (2015). In situ imaging of vortices in Bose-Einstein condensates. PHYSICAL REVIEW A, 91(2).
- Billam, T. P., Reeves, M. T., Anderson, B. P., & Bradley, A. S. (2014). Onsager-Kraichnan Condensation in Decaying Two-Dimensional Quantum Turbulence. PHYSICAL REVIEW LETTERS, 112(14).More infoDespite the prominence of Onsager's point-vortex model as a statistical description of 2D classical turbulence, a first-principles development of the model for a realistic superfluid has remained an open problem. Here we develop a mapping of a system of quantum vortices described by the homogeneous 2D Gross-Pitaevskii equation (GPE) to the point-vortex model, enabling Monte Carlo sampling of the vortex microcanonical ensemble. We use this approach to survey the full range of vortex states in a 2D superfluid, from the vortex-dipole gas at positive temperature to negative-temperature states exhibiting both macroscopic vortex clustering and kinetic energy condensation, which we term an Onsager-Kraichnan condensate (OKC). Damped GPE simulations reveal that such OKC states can emerge dynamically, via aggregation of small-scale clusters into giant OKC clusters, as the end states of decaying 2D quantum turbulence in a compressible, finite-temperature superfluid. These statistical equilibrium states should be accessible in atomic Bose-Einstein condensate experiments.
- Reeves, M. T., Billam, T. P., Anderson, B. P., & Bradley, A. S. (2014). Signatures of coherent vortex structures in a disordered two-dimensional quantum fluid. PHYSICAL REVIEW A, 89(5).More infoThe emergence of coherent rotating structures is a phenomenon characteristic of both classical and quantum two-dimensional (2D) turbulence. In this work we show theoretically that the coherent vortex structures that emerge in decaying 2D quantum turbulence can approach quasiclassical rigid-body rotation, obeying the Feynman rule of constant average areal vortex density while remaining spatially disordered. By developing a rigorous link between the velocity probability distribution and the quantum kinetic energy spectrum over wave number k, we show that the coherent vortex structures are associated with a k(3) power law in the infrared region of the spectrum, and a well-defined spectral peak that is a physical manifestation of the largest structures. We discuss the possibility of realizing coherent structures in Bose-Einstein condensate experiments and present Gross-Pitaevskii simulations showing that this phenomenon, and its associated spectral signatures, can emerge dynamically from feasible initial vortex configurations.
- White, A. C., Anderson, B. P., & Bagnato, V. S. (2014). Vortices and turbulence in trapped atomic condensates. PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 111, 4719-4726.
- Wilson, K. E., Samson, E. C., Newman, Z. L., Neely, T. W., Anderson, B. P., Madison, K., Wang, Y., Rey, A., & Bongs, K. (2014). EXPERIMENTAL METHODS FOR GENERATING TWO-DIMENSIONAL QUANTUM TURBULENCE IN BOSE-EINSTEIN CONDENSATES. ANNUAL REVIEW OF COLD ATOMS AND MOLECULES, VOL 1, 1, 261-298.More infoBose-Einstein condensates of dilute gases are well-suited for investigations of vortex dynamics and turbulence in quantum fluids, yet there has been little experimental research into the approaches that may be most promising for generating states of two-dimensional turbulence in these systems. Here we give an overview of techniques for generating the large and disordered vortex distributions associated with two-dimensional quantum turbulence. We focus on describing methods explored in our Bose-Einstein condensation laboratory, and discuss the suitability of these methods for studying various aspects of two-dimensional quantum turbulence. We also summarize some of the open questions regarding our own understanding of these mechanisms of two-dimensional quantum turbulence generation in condensates. We find that while these disordered distributions of vortices can be generated by a variety of techniques, further investigation is needed to identify methods for obtaining quasi-steady-state quantum turbulence in condensates.
- Kuopanportti, P., Anderson, B. P., & Möttönen, M. (2013). Vortex pump for Bose-Einstein condensates utilizing a time-averaged orbiting potential trap. Physical Review A - Atomic, Molecular, and Optical Physics, 87(3).More infoAbstract: We show that topological vortex pumping can be implemented for a dilute Bose-Einstein condensate confined in a magnetic time-averaged orbiting potential trap with axial optical confinement. Contrary to earlier proposals for the vortex pump, we do not employ an additional optical potential to trap the condensate in the radial direction, but instead, the radial confinement is provided by the magnetic field throughout the pumping cycle. By performing numerical simulations based on the spin-1 Gross-Pitaevskii equation, we find that several pumping cycles can be carried out to produce a highly charged vortex before a majority of the particles escape from the trap or before the vortex splits into singly charged vortices. On the other hand, we observe that an additional, relatively weak optical plug potential is efficient in preventing splitting and reducing particle loss. With these results, we hope to bring the vortex pump closer to experimental realization. © 2013 American Physical Society.
- Law, K. J., Neely, T. W., Kevrekidis, P. G., Anderson, B. P., Bradley, A. S., & Carretero-Gonzalez, R. (2014). Dynamic and energetic stabilization of persistent currents in Bose-Einstein condensates. PHYSICAL REVIEW A, 89(5).More infoWe study conditions under which vortices in a highly oblate harmonically trapped Bose-Einstein condensate (BEC) can be stabilized due to pinning by a blue-detuned Gaussian laser beam, with particular emphasis on the potentially destabilizing effects of laser beam positioning within the BEC. Our approach involves theoretical and numerical exploration of dynamically and energetically stable pinning of vortices with winding number up to S = 6, in correspondence with experimental observations. Stable pinning is quantified theoretically via Bogoliubov-de Gennes excitation spectrum computations and confirmed via direct numerical simulations for a range of conditions similar to those of experimental observations. The theoretical and numerical results indicate that the pinned winding number, or equivalently the winding number of the superfluid current about the laser beam, decays as a laser beam of fixed intensity moves away from the BEC center. Our theoretical analysis helps explain previous experimental observations and helps define limits of stable vortex pinning for future experiments involving vortex manipulation by laser beams.
- Neely, T. W., Bradley, A. S., Samson, E. C., Rooney, S. J., Wright, E. M., Law, K. J., Carretero-González, R., Kevrekidis, P. G., Davis, M. J., & Anderson, B. P. (2013). Characteristics of two-dimensional quantum turbulence in a compressible superfluid. Physical Review Letters, 111(23).More infoAbstract: Fluids subjected to suitable forcing will exhibit turbulence, with characteristics strongly affected by the fluid's physical properties and dimensionality. In this work, we explore two-dimensional (2D) quantum turbulence in an oblate Bose-Einstein condensate confined to an annular trapping potential. Experimentally, we find conditions for which small-scale stirring of the condensate generates disordered 2D vortex distributions that dissipatively evolve toward persistent currents, indicating energy transport from small to large length scales. Simulations of the experiment reveal spontaneous clustering of same-circulation vortices and an incompressible energy spectrum with k -5/3 dependence for low wave numbers k. This work links experimentally observed vortex dynamics with signatures of 2D turbulence in a compressible superfluid. © 2013 American Physical Society.
- Reeves, M. T., Billam, T. P., Anderson, B. P., & Bradley, A. S. (2013). Inverse energy cascade in forced two-dimensional quantum turbulence. Physical Review Letters, 110(10).More infoAbstract: We demonstrate an inverse energy cascade in a minimal model of forced 2D quantum vortex turbulence. We simulate the Gross-Pitaevskii equation for a moving superfluid subject to forcing by a stationary grid of obstacle potentials, and damping by a stationary thermal cloud. The forcing injects large amounts of vortex energy into the system at the scale of a few healing lengths. A regime of forcing and damping is identified where vortex energy is efficiently transported to large length scales via an inverse energy cascade associated with the growth of clusters of same-circulation vortices, a Kolmogorov scaling law in the kinetic energy spectrum over a substantial inertial range, and spectral condensation of kinetic energy at the scale of the system size. Our results provide clear evidence that the inverse energy cascade phenomenon, previously observed in a diverse range of classical systems, can also occur in quantum fluids. © 2013 American Physical Society.
- Rooney, S. J., Neely, T. W., Anderson, B. P., & Bradley, A. S. (2013). Persistent-current formation in a high-temperature Bose-Einstein condensate: An experimental test for classical-field theory. Physical Review A - Atomic, Molecular, and Optical Physics, 88(6).More infoAbstract: Experimental stirring of a toroidally trapped Bose-Einstein condensate at high temperature generates a disordered array of quantum vortices that decays via thermal dissipation to form a macroscopic persistent current. We perform three-dimensional numerical simulations of the experimental sequence within the stochastic projected Gross-Pitaevskii equation using ab initio determined reservoir parameters. We find that both damping and noise are essential for describing the dynamics of the high-temperature Bose field. The theory gives a quantitative account of the formation of a persistent current, with no fitted parameters. © 2013 American Physical Society.
- Bradley, A. S., & Anderson, B. P. (2012). Energy spectra of vortex distributions in two-Dimensional quantum turbulence. Physical Review X, 2(4).More infoAbstract: We theoretically explore key concepts of two-dimensional turbulence in a homogeneous compressible superfluid described by a dissipative two-dimensional Gross-Pitaeveskii equation. Such a fluid supports quantized vortices that have a size characterized by the healing length ξ.We show that, for the divergencefree portion of the superfluid velocity field, the kinetic-energy spectrum over wave number k may be decomposed into an ultraviolet regime (k ≫ ξ-1) having a universal k-3 scaling arising from the vortex core structure, and an infrared regime (k ≪ ξ-1) with a spectrum that arises purely from the configuration of the vortices. The Novikov power-law distribution of intervortex distances with exponent -1/3 for vortices of the same sign of circulation leads to an infrared kinetic-energy spectrum with a Kolmogorov k-5/3 power law, which is consistent with the existence of an inertial range. The presence of these k-3 and k-5/3 power laws, together with the constraint of continuity at the smallest configurational scale k ≈ ξ-1, allows us to derive a new analytical expression for the Kolmogorov constant that we test against a numerical simulation of a forced homogeneous, compressible, two-dimensional superfluid. The numerical simulation corroborates our analysis of the spectral features of the kinetic-energy distribution, once we introduce the concept of a clustered fraction consisting of the fraction of vortices that have the same sign of circulation as their nearest neighboring vortices. Our analysis presents a new approach to understanding two-dimensional quantum turbulence and interpreting similarities and differences with classical twodimensional turbulence, and suggests new methods to characterize vortex turbulence in two-dimensional quantum fluids via vortex position and circulation measurements.
- Reeves, M. T., Anderson, B. P., & Bradley, A. S. (2012). Classical and quantum regimes of two-dimensional turbulence in trapped Bose-Einstein condensates. Physical Review A - Atomic, Molecular, and Optical Physics, 86(5).More infoAbstract: We investigate two-dimensional turbulence in finite-temperature trapped Bose-Einstein condensates within damped Gross-Pitaevskii theory. Turbulence is produced via circular motion of a Gaussian potential barrier stirring the condensate. We systematically explore a range of stirring parameters and identify three regimes, characterized by the injection of distinct quantum vortex structures into the condensate: (A) periodic vortex dipole injection, (B) irregular injection of a mixture of vortex dipoles and co-rotating vortex clusters, and (C) continuous injection of oblique solitons that decay into vortex dipoles. Spectral analysis of the kinetic energy associated with vortices reveals that regime (B) can intermittently exhibit a Kolmogorov k -5/3 power law over almost a decade of length or wave-number (k) scales. The kinetic energy spectrum of regime (C) exhibits a clear k-3/2 power law associated with an inertial range for weak-wave turbulence and a k-7/2 power law for high wave numbers. We thus identify distinct regimes of forcing for generating either two-dimensional quantum turbulence or classical weak-wave turbulence that may be realizable experimentally. © 2012 American Physical Society.
- Anderson, B. P., Neely, T. W., Bradley, A. S., Samson, E. C., Rooney, S. J., Wright, E. M., Law, K. J., Carretero-González, R., Kevrekidis, P. G., & Davis, M. J. (2011). Two-dimensional quantum turbulence in Bose-Einstein condensates. 2011 Int. Quantum Electron. Conf., IQEC 2011 and Conf. Lasers and Electro-Optics, CLEO Pacific Rim 2011 Incorporating the Australasian Conf. Optics, Lasers and Spectroscopy and the Australian Conf., 1071-.More infoAbstract: We report the experimental generation of two-dimensional quantum turbulence in dilute-gas Bose-Einstein condensates by stirring the condensate with a laser beam, and the decay of the turbulent state to a large-scale flow in the form of a persistent current in a toroidal trap geometry. From numerical simulations of the stirring process, we characterize the dynamics of the quantized vortices in the condensate, and analyze the kinetic energy spectrum. Our observations are consistent with basic features of two-dimensional turbulence in classical incompressible fluids. © 2011 IEEE.
- Anderson, B. P., Neely, T. W., Bradley, A. S., Samson, E. C., Rooney, S. J., Wright, E. M., Law, K. J., Carretero-González, R., Kevrekidis, P. G., & Davis, M. J. (2011). Two-dimensional quantum turbulence in bose-einstein condensates. Optics InfoBase Conference Papers, 1071-.More infoAbstract: We report the experimental generation of two-dimensional quantum turbulence in dilute-gas Bose-Einstein condensates by stirring the condensate with a laser beam, and the decay of the turbulent state to a large-scale flow in the form of a persistent current in a toroidal trap geometry. From numerical simulations of the stirring process, we characterize the dynamics of the quantized vortices in the condensate, and analyze the kinetic energy spectrum. Our observations are consistent with basic features of two-dimensional turbulence in classical incompressible fluids. © 2011 AOS.
- Rooney, S. J., Blakie, P. B., Anderson, B. P., & Bradley, A. S. (2011). Suppression of Kelvon-induced decay of quantized vortices in oblate Bose-Einstein condensates. Physical Review A - Atomic, Molecular, and Optical Physics, 84(2).More infoAbstract: We study the Kelvin mode excitations on a vortex line in a three-dimensional trapped Bose-Einstein condensate at finite temperature. Our stochastic Gross-Pitaevskii simulations show that the activation of these modes can be suppressed by tightening the confinement along the direction of the vortex line, leading to a strong suppression in the vortex decay rate as the system enters a regime of two-dimensional vortex dynamics. As the system approaches the condensation transition temperature, we find that the vortex decay rate is strongly sensitive to dimensionality and temperature, observing a large enhancement for quasi-two-dimensional traps. Three-dimensional simulations of the recent vortex dipole decay experiment of Neely confirm two-dimensional vortex dynamics and predict a dipole lifetime consistent with experimental observations and suppression of Kelvon-induced vortex decay in highly oblate condensates. © 2011 American Physical Society.
- Anderson, B. P. (2010). Resource article: Experiments with vortices in superfluid atomic gases. Journal of Low Temperature Physics, 161(5-6), 574-602.More infoAbstract: Observations of quantized vortices in dilute-gas Bose-Einstein condensates were first reported in 1999. Over the next 10 years, more than 70 papers describing experiments involving vortices in superfluid atomic gases were published in scientific journals. This resource article provides a guide to the published experimental studies related to quantized vortices in atomic Bose-Einstein condensates and superfluid Fermi gases. A BibTex-formatted bibliography document listing these published studies is also available electronically. © Springer Science+Business Media, LLC 2010.
- Neely, T. W., Samson, E. C., Bradley, A. S., Davis, M. J., & Anderson, B. P. (2010). Observation of vortex dipoles in an oblate Bose-Einstein condensate. Physical Review Letters, 104(16).More infoAbstract: We report experimental observations and numerical simulations of the formation, dynamics, and lifetimes of single and multiply charged quantized vortex dipoles in highly oblate dilute-gas Bose-Einstein condensates (BECs). We nucleate pairs of vortices of opposite charge (vortex dipoles) by forcing superfluid flow around a repulsive Gaussian obstacle within the BEC. By controlling the flow velocity we determine the critical velocity for the nucleation of a single vortex dipole, with excellent agreement between experimental and numerical results. We present measurements of vortex dipole dynamics, finding that the vortex cores of opposite charge can exist for many seconds and that annihilation is inhibited in our trap geometry. For sufficiently rapid flow velocities, clusters of like-charge vortices aggregate into long-lived multiply charged dipolar flow structures. © 2010 The American Physical Society.
- Davis, M. C., Carretero-González, R., Shi, Z., Law, K. J., Kevrekidis, P. G., & Anderson, B. P. (2009). Manipulation of vortices by localized impurities in Bose-Einstein condensates. Physical Review A - Atomic, Molecular, and Optical Physics, 80(2).More infoAbstract: We consider the manipulation of Bose-Einstein condensate vortices by optical potentials generated by focused laser beams. It is shown that for appropriate choices of the laser strength and width it is possible to successfully transport vortices to various positions inside the trap confining the condensate atoms. Furthermore, the full bifurcation structure of possible stationary single-charge vortex solutions in a harmonic potential with this type of impurity is elucidated. The case when a moving vortex is captured by a stationary laser beam is also studied, as well as the possibility of dragging the vortex by means of periodic optical lattices. © 2009 The American Physical Society.
- Carretero-González, R., Anderson, B. P., Kevrekidis, P. G., Frantzeskakis, D. J., & Weiler, C. N. (2008). Dynamics of vortex formation in merging Bose-Einstein condensate fragments. Physical Review A - Atomic, Molecular, and Optical Physics, 77(3).More infoAbstract: We study the formation of vortices in a Bose-Einstein condensate (BEC) that has been prepared by allowing isolated and independent condensed fragments to merge together. We focus on the experimental setup of Scherer [Phys. Rev. Lett. 98, 110402 (2007)], where three BECs are created in a magnetic trap that is segmented into three regions by a repulsive optical potential; the BECs merge together as the optical potential is removed. First, we study the two-dimensional case; in particular, we examine the effects of the relative phases of the different fragments and the removal rate of the optical potential on the vortex formation. We find that many vortices are created by instant removal of the optical potential regardless of relative phases, and that fewer vortices are created if the intensity of the optical potential is gradually ramped down and the condensed fragments gradually merge. In all cases, self-annihilation of vortices of opposite charge is observed. We also find that for sufficiently long barrier ramp times, the initial relative phases between the fragments leave a clear imprint on the resulting topological configuration. Finally, we study the three-dimensional system and the formation of vortex lines and vortex rings due to the merger of the BEC fragments; our results illustrate how the relevant vorticity is manifested for appropriate phase differences, as well as how it may be masked by the planar projections observed experimentally. © 2008 The American Physical Society.
- Law, K. J., Kevrekidis, P. G., Anderson, B. P., Carretero-González, R., & Frantzeskakis, D. J. (2008). Structure and stability of two-dimensional Bose-Einstein condensates under both harmonic and lattice confinement. Journal of Physics B: Atomic, Molecular and Optical Physics, 41(19).More infoAbstract: In this work, we study two-dimensional Bose-Einstein condensates confined by both a cylindrically symmetric harmonic potential and an optical lattice with equal periodicity in two orthogonal directions. We first identify the spectrum of the underlying two-dimensional linear problem through multiple-scale techniques. Then, we use the results obtained in the linear limit as a starting point for the existence and stability analysis of the lowest energy states, emanating from the linear ones, in the nonlinear problem. Two-parameter continuations of these states are performed for increasing nonlinearity and optical lattice strengths, and their instabilities and temporal evolution are investigated. It is found that the ground state as well as some of the excited states may be stable or weakly unstable for both attractive and repulsive interatomic interactions. Higher excited states are typically found to be increasingly more unstable. © 2008 IOP Publishing Ltd.
- Weiler, C. N., Neely, T. W., Scherer, D. R., Bradley, A. S., Davis, M. J., & Anderson, B. P. (2008). Spontaneous vortices in the formation of Bose-Einstein condensates. Nature, 455(7215), 948-951.More infoAbstract: Phase transitions are ubiquitous in nature, and can be arranged into universality classes such that systems having unrelated microscopic physics show identical scaling behaviour near the critical point. One prominent universal element of many continuous phase transitions is the spontaneous formation of topological defects during a quench through the critical point. The microscopic dynamics of defect formation in such transitions are generally difficult to investigate, particularly for superfluids. However, Bose-Einstein condensates (BECs) offer unique experimental and theoretical opportunities for probing these details. Here we present an experimental and theoretical study of the BEC phase transition of a trapped atomic gas, in which we observe and statistically characterize the spontaneous formation of vortices during condensation. Using microscopic theories that incorporate atomic interactions and quantum and thermal fluctuations of a finite-temperature Bose gas, we simulate condensation and observe vortex formation in close quantitative agreement with our experimental results. Our studies provide further understanding of the development of coherence in superfluids, and may allow for direct investigation of universal phase transition dynamics. ©2008 Macmillan Publishers Limited. All rights reserved.
- Scherer, D. R., Weiler, C. N., Neely, T. W., & Anderson, B. P. (2007). Vortex formation by merging of multiple trapped bose-einstein condensates. Physical Review Letters, 98(11).More infoAbstract: We report observations of vortex formation by merging and interfering multiple Rb87 Bose-Einstein condensates (BECs) in a confining potential. In this experiment, a single harmonic potential well is partitioned into three sections by a barrier, enabling the simultaneous formation of three independent, uncorrelated BECs. The BECs may either automatically merge together during their growth, or for high-energy barriers, the BECs can be merged together by barrier removal after their formation. Either process may instigate vortex formation in the resulting BEC, depending on the initially indeterminate relative phases of the condensates and the merging rate. © 2007 The American Physical Society.
- Anderson, B. P., Dholakia, K., & Wright, E. M. (2003). Atomic-phase interference devices based on ring-shaped Bose-Einstein condensates: Two-ring case. Physical Review A - Atomic, Molecular, and Optical Physics, 67(3), 033601/1-033601/8.More infoAbstract: A theoretical investigation of a pair of ring Bose-Einstein condensates (BECs) coupled by tunneling as the simplest example of a potential atomic-phase interference device (APHID) is presented. It is shown that the two-ring APHID has interesting ground-state properties, with density profiles reminiscent of dark soliton states around the point of contact of the rings. Furthermore, it is demonstrated that Josephson oscillations between the two rings can occur, and that these oscillations are sensitive to the state of rotation of the APHID.
- Anderson, B. P., & Kasevich, M. A. (2001). Loading a vapor-cell magneto-optic trap using light-induced atom desorption. Physical Review A - Atomic, Molecular, and Optical Physics, 63(2), 1-6.More infoAbstract: Low-intensity white light was used to increase the loading rate of 87Rb atoms into a vapor-cell magnetooptic trap by inducing nonthermal desorption of Rb atoms from the stainless-steel walls of the vapor cell. An increased Rb partial pressure reached a new equilibrium value in fewer than 10 s after switching on the broadband light source. After the source was turned off, the partial pressure returned to its previous value in 1/e times as short as 10 s. ©2001 The American Physical Society.
- Anderson, B. P., Haljan, P. C., Regal, C. A., Feder, D. L., Collins, L. A., Clark, C. W., & Cornell, E. A. (2001). Watching dark solitons decay into vortex rings in a Bose-Einstein condensate. Physical Review Letters, 86(14), 2926-2929.More infoPMID: 11290074;Abstract: Dark solitons were created in two-component Bose-Einstein condensates, where the soliton exists in one of the condensate components and the soliton nodal plane is filled with the second component. The filled solitons are stable for hundreds of milliseconds. The filling can be selectively removed, making the soliton more susceptible to dynamical instabilities. For a condensate in a spherically symmetric potential, these instabilities cause the dark soliton to decay into stable vortex rings.
- Haljan, P. C., Anderson, B. P., Coddington, I., & Comell, E. A. (2001). Use of surface-wave spectroscopy to characterize tilt modes of a vortex in a Bose-Einstein condensate. Physical Review Letters, 86(14), 2922-2925.More infoPMID: 11290073;Abstract: A nondestructive method of vortex detection was described and was used to characterize the tilt modes of a bare vortex in a trapped Bose-Einstein condensate (BEC). Control over the tilt of a vortex was demonstrated, including the suppression of tilting altogether. The suppression of tilting, which maintains the visibility of vortices out to long times, permits the study of the lifetime of vortices at finite temperature.
- Anderson, B. P., Haljan, P. C., Wieman, C. E., & Cornell, E. A. (2000). Vortex precession in Bose-Einstein condensates: observations with filled and empty cores. Physical Review Letters, 85(14), 2857-2860.More infoPMID: 11005953;Abstract: Vortex dynamics in bare- and filled-core vortices in dilute-gas Bose-Einstein condensates (BECs) were measured using a combination of destructive and nondestructive imaging techniques. Vortex precision frequencies showed only modest dependence on the radius and content of the vortex core.
- Haljan, P. C., Anderson, B. P., Matthews, M. R., Hall, D. S., Wieman, C. E., & Cornell, E. A. (2000). Vortices in a Bose Einstein Condensate. Conference on Quantum Electronics and Laser Science (QELS) - Technical Digest Series, 201-202.More infoAbstract: Using a method proposed by Williams and Holland, an attempt was made to prepare vortices, macroscopic quantum states with quantized angular momentum in trapped BEC of 87Rb. A coupling field allows interconversion between two-component condensates.
- Haljan, P. C., Anderson, B. P., Wieman, C. E., & Cornell, E. A. (2000). Using surface excitations to detect bare vortices in a Bose-Einstein condensate. Conference on Quantum Electronics and Laser Science (QELS) - Technical Digest Series, 291-292.More infoAbstract: The lifetime and dynamics of vortices in a Bose-Einstein condensate (BEC) of dilute atomic vapor can shed light on the superfluid character of BEC in alkalis. An overview is given on the various efforts at preparing such vortices. Focus is on an alternative method of vortex detection which should be less sensitive to deformation of the vortex line.
- Anderson, B. P., & Kasevich, M. A. (1999). Spatial observation of Bose-Einstein condensation of 87Rb in a confining potential. Physical Review A - Atomic, Molecular, and Optical Physics, 59(2-3), R938-R941.More infoAbstract: Bose-Einstein condensation of 87Rb has been observed in a vapor cell time-averaged orbiting potential trap, and the trapped condensates have been studied using in situ absorption and dark-ground imaging methods. Condensates of 3 × 104 atoms were observed after 26 s of evaporative cooling. The evaporative cooling sequence consisted of a combination of cooling with ramping magnetic-field strengths and radio-frequency-induced cooling. The measured sizes, numbers of atoms, and transition temperatures of the condensates are consistent with theoretical predictions that include the effects of atomic interactions.
- Anderson, B., Gustavson, T., Landragin, A., McGuirk, J., Snadden, M., Yasuda, M., & Kasevich, M. (1999). Precision atom interferometry. Journal of the Communications Research Laboratory, 46(3), 449-451.More infoAbstract: Recent progress in the development of atom interferometer-based gyroscopes, accelerometers and gravity gradiometers will be presented.
- Matthews, M. R., Anderson, B. P., Haljan, P. C., Hall, D. S., Holland, M. J., Williams, J. E., Wieman, C. E., & Cornell, E. A. (1999). Watching a Superfluid Untwist Itself: Recurrence of Rabi Oscillations in a Bose-Einstein Condensate. Physical Review Letters, 83(17), 3358-3361.More infoAbstract: The order parameter of a condensate with two internal states can continuously distort in such a way as to remove twists that have been imposed along its length. We observe this effect experimentally in the collapse and recurrence of Rabi oscillations in a magnetically trapped, two-component Bose-Einstein condensate of 87Rb.
- Matthews, M. R., Anderson, B. P., Haljan, P. C., Hall, D. S., Wieman, C. E., & Cornell, E. A. (1999). Vortices in a bose-einstein condensate. Physical Review Letters, 83(13), 2498-2501.More infoAbstract: We have created vortices in two-component Bose-Einstein condensâtes. The vortex state was created through a coherent process involving the spatial and temporal control of interconversion between the two components. Using an interference technique, we map the phase of the vortex state to confirm that it possesses angular momentum. We can create vortices in either of the two components and have observed differences in the dynamics and stability. © 1999 The American Physical Society.
- Anderson, B. P., & Kasevich, M. A. (1998). Macroscopic quantum interference from atomic tunnel arrays. Science, 282(5394), 1686-1689.More infoAbstract: Interference of atomic de Broglie waves tunneling from a vertical array of macroscopically populated traps has been observed. The traps were located in the antinodes of an optical standing wave and were loaded from a Bose- Einstein condensate. Tunneling was induced by acceleration due to gravity, and interference was observed as a train of falling pulses of atoms. In the limit of weak atomic interactions, the pulse frequency is determined by the gravitational potential energy difference between adjacent potential wells. The effect is closely related to the ac Josephson effect observed in superconducting electronic systems.
- Anderson, B. P., Gustavson, T. L., & Kasevich, M. A. (1996). Atom trapping in nondissipative optical lattices. Physical Review A - Atomic, Molecular, and Optical Physics, 53(6), R3727-R3730.More infoAbstract: Laser-cooled 7Li atoms have been confined in three-dimensional spatially periodic potentials that are nearly conservative. The potentials were formed from the intersection of four laser beams far-detuned from the optical resonance. By adjusting the relative orientations of the beams, lattices with primitive translation vectors larger than the laser light wavelength were created. We achieved an effective temperature of ∼80 μK through adiabatic reduction of the confining potential strength, and prepared ensembles with effective temperatures of ∼1.8 μK by initially confining atoms in weak potentials.
- Anderson, B. P., & Kasevich, M. A. (1994). Enhanced loading of a magneto-optic trap from an atomic beam. Physical Review A, 50(5), R3581-R3584.More infoAbstract: We demonstrate enhanced loading of a Li7 magneto-optic trap by broadening the frequency spectrum of the laser trapping light with a resonant electro-optic modulator. We achieve an 20-fold improvement in the loading rate over that obtained without a broadened spectrum when directly capturing atoms from a divergent atomic beam. © 1994 The American Physical Society.