Publications (76)136.61 Total impact
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ABSTRACT: Radiofrequency (RF) atomic magnetometers (AMs) can be used in many applications, such as magnetic resonance imaging and nuclear quadrupole resonance. Highdensity AMs provide both superior sensitivity and large bandwidth. Previously, highdensity potassium AMs were demonstrated, but these magnetometers have various disadvantages, such as hightemperature of operation and bulky design. We demonstrate a rubidium87 RF AM with 5 fT/Hz1/2 sensitivity (3 fT Hz1/2 probe noise), which is comparable to that of the best potassium magnetometers. Our magnetometer also features a simple fiberoptic design, providing maximum flexibility for magneticfield measurements.Applied Physics Letters 01/2014; 104(2):0235040235043. · 3.79 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: Bessel beams are plane waves with amplitude profiles described by Bessel functions. They are important because they propagate ‘diffractionfree’ and because they can carry orbital angular momentum. Here we report the creation of a Bessel beam of de Broglie matter waves. The Bessel beam is produced by the free evolution of a thin toroidal atomic BoseEinstein condensate (BEC) which has been set into rotational motion. By attempting to stir it at different rotation rates, we show that the toroidal BEC can only be made to rotate at discrete, equally spaced frequencies, demonstrating that circulation is quantized in atomic BECs. The method used here can be viewed as a form of wavefunction engineering which might be developed to implement cold atom matter wave holography.12/2013; 16(1).  [Show abstract] [Hide abstract]
ABSTRACT: Nonzero curvature in a waveguide leads to the appearance of an attractive quantum potential which crucially affects the dynamics in matterwave circuits. Using methods of supersymmetric quantum mechanics, pairs of bent waveguides are found whose geometryinduced potentials share the same scattering properties. As a result, reflectionless waveguides, dual to the straight waveguide, are identified. Strictly isospectral waveguides are also found by modulating the depth of the trapping potential. Numerical simulations are used to demonstrate the efficiency of these approaches.Scientific reports. 11/2013; 4.  [Show abstract] [Hide abstract]
ABSTRACT: We show that repulsive neutralatom impurities in a dilute gas BoseEinstein condensate (BEC) can selflocalize in bubble polaron states formally analogous to electron bubbles in helium. The BEC is then the first impurity host medium known to exhibit both LandauPekar polaron states akin to that of selflocalized electrons in a dielectric lattice and selflocalized bubble polaron states. We find that the neutral BECimpurity system is fully characterized by only two dimensionless coupling constants and that a single BEC impurity can be steered adiabatically from the LandauPekar to the bubble region. The adiabatic change is that of a crossover, not a transition.Physical Review A 11/2013; 88(5). · 3.04 Impact Factor 
Article: Creation of matter wave Bessel beams
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ABSTRACT: Bessel beams are plane waves with amplitude profiles described by Bessel functions. They are important because of their property of limited diffraction and their capacity to carry orbital angular momentum. Here we report the creation of a Bessel beam of de Broglie matter waves. The Bessel beam is produced by the free evolution of a thin toroidal atomic BoseEinstein condensate (BEC) which has been set into rotational motion. By attempting to stir it at different rotation rates, we show that the toroidal BEC can only be made to rotate at discrete, equallyspaced frequencies, demonstrating that circulation is quantized in atomic BECs. The method used here to generate matter wave Bessel beams with a Painted Potential can be viewed as a form of wavefunction engineering which might be extended to implement arbitrary cold atom matter wave holography.09/2013;  [Show abstract] [Hide abstract]
ABSTRACT: We report the creation of ideal Josephson junctions in a toroidal dilute gas BoseEinstein condensate (BEC). The demonstrated configuration of a pair of junctions on a multiplyconnected BEC is the cold atom analog of the wellknown dc Superconducting Quantum Inteference Device (SQUID). We measure the critical current of the junctions, observe Josephson effects, and find dynamic behavior that is in good agreement with the simple Josephson equations for an ideal tunnel junction with a sinusoidal currentphase relation. The junctions and toroidal trap are created with the Painted Potential, a timeaveraged optical dipole potential technique which will allow scaling to more complex BEC circuit geometries than the single AtomSQUID case reported here. Since rotation plays the same role in the Atom SQUID as magnetic field does in the dc SQUID magnetometer, the device has potential as a compact rotation sensor. It may also be useful for creating macroscopic Schr\"odinger Cat states.Physical Review Letters 04/2013; 111(20). · 7.94 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: Polarons, selflocalized composite objects formed by the interaction of a single impurity particle with a host medium, are a paradigm of strong interaction manybody physics. We show that dilute gas BoseEinstein condensates (BEC's) are the first medium known to selflocalize the same impurity particles both in a LandauPekar polaron state akin to that of selflocalized electrons in a dielectric lattice, and in a bubble state akin to that of electron bubbles in helium. We also show that the BECimpurity system is fully characterized by just two dimensionless coupling constants, and that it can be adiabatically steered from the LandauPekar regime to the bubble regime in a smooth crossover trajectory.04/2013;  [Show abstract] [Hide abstract]
ABSTRACT: A method is proposed to drive an ultrafast nonadiabatic dynamics of an ultracold gas trapped in a timedependent box potential. The resulting state is free from spurious excitations associated with the breakdown of adiabaticity, and preserves the quantum correlations of the initial state up to a scaling factor. The process relies on the existence of an adiabatic invariant and the inversion of the dynamical selfsimilar scaling law dictated by it. Its physical implementation generally requires the use of an auxiliary expulsive potential. The method is extended to a broad family of interacting manybody systems. As illustrative examples we consider the ultrafast expansion of a TonksGirardeau gas and of BoseEinstein condensates in different dimensions, where the method exhibits an excellent robustness against different regimes of interactions and the features of an experimentally realizable box potential.Scientific Reports 01/2012; 2:648. · 2.93 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: Quantized circulation, one of the most important consequences of BoseEinstein condensation, is fundamental to the understanding of superfluid phenomena. In a toroidal trap, Bose condensed atoms should flow with a well defined winding number, which makes it an ideal system to demonstrate the quantized nature of circulation. We used a scanning laser beam to create a toroidal trap [1]. To rotate the atoms, a small potential barrier within the toroidal trap was rotated at a certain frequency and then the barrier was lowered to create a quantized flow state. The winding number of the flow was determined by the diameter of the central hole seen in a time of flight image of the condensate. The measurement showed diameters increasing stepwise with the stirring frequency. We observed flows with winding number up to 5. This is a clear demonstration of the quantization of the flow of atoms in a toroidal trap. Further study of critical velocity and metastability of flow of atoms will be very important in understanding the nature of superfluidity of atoms in a toroidal trap, especially in a 1D limit.[4pt] [1] K. Henderson, C. Ryu, C. MacCormick, and M. G. Boshier, New Journal of Physics 11, 043030 (2009).03/2010;  [Show abstract] [Hide abstract]
ABSTRACT: We describe a method ootnotetextT. E. Wall et al., Phys. Rev. A 78, 062509 (2008) for determining the radiative decay properties of a molecule by studying the saturation of laserinduced fluorescence and the associated power broadening of spectral lines. The fluorescence saturates because the molecules decay to states that are not resonant with the laser. The amplitudes and widths of two hyperfine components of a spectral line are measured over a range of laser intensities and the results compared to a model of the lasermolecule interaction. Using this method we measure the lifetime of the A(v'=0) state of CaF to be tau=19.2±0.7 ns, and the FranckCondon factor for the transition to the X(v=0) state to be Z=0.9870.019^+0.013. In addition, our analysis provides a measure of the hyperfine interval in the lowestlying state of A(v'=0), deltae=4.8±1.1 MHz. A FranckCondon factor close to 1 opens the possiblity of implementing a cycling transition with a small number of additional repump frequencies. We discuss possible schemes of laser cooling CaF or other alkaline earth monofluorides.05/2009;  [Show abstract] [Hide abstract]
ABSTRACT: There is a pressing need for robust and straightforward methods to create potentials for trapping BoseEinstein condensates which are simultaneously dynamic, fully arbitrary, and sufficiently stable to not heat the ultracold gas. We show here how to accomplish these goals, using a rapidlymoving laser beam that "paints" a timeaveraged optical dipole potential in which we create BECs in a variety of geometries, including toroids, ring lattices, and square lattices. Matter wave interference patterns confirm that the trapped gas is a condensate. As a simple illustration of dynamics, we show that the technique can transform a toroidal condensate into a ring lattice and back into a toroid. The technique is general and should work with any sufficiently polarizable lowenergy particles. Comment: Minor text changes and three references added. This is the final version published in New Journal of PhysicsNew Journal of Physics 02/2009; · 4.06 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We describe a method for determining the radiative decay properties of a molecule by studying the saturation of laserinduced fluorescence and the associated power broadening of spectral lines. The fluorescence saturates because the molecules decay to states that are not resonant with the laser. The amplitudes and widths of two hyperfine components of a spectral line are measured over a range of laser intensities and the results compared to a model of the lasermolecule interaction. Using this method we measure the lifetime of the A(v'=0) state of CaF to be tau=19.2 \pm 0.7 ns, and the FranckCondon factor for the transition to the X(v=0) state to be Z=0.987 (+0.013  0.019). In addition, our analysis provides a measure of the hyperfine interval in the lowestlying state of A(v'=0), Delta_e=4.8 \pm 1.1 MHz.Physical Review A 01/2008; 78(6). · 3.04 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We report progress towards making a precise measurement of the 2S Lamb shift in singlyionised helium by spectroscopy of the 2S3S transition. The motivation for the experiment is discussed with reference to recent developments in the theory of quantum electrodynamics (QED) and a description of the apparatus and techniques used is given.12/2007: pages 303313; 
Article: Laser spectroscopy of simple atoms
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ABSTRACT: This paper discusses some recent and ongoing experiments involving the application of laser spectroscopy to light hydrogenic atoms. Several theoretical groups have recently made substantial advances in the calculation of energy level corrections due to quantum electrodynamics, the theory most directly tested by these experiments. At the same time optical spectroscopy of hydrogen has reached the point where uncertainties due to strong interactions are an important limitation in the interpretation of measurements. This problem is much less severe in the case of the singlyionised He+ ion, motivating laser spectroscopic measurements of Lamb shifts in that system. New experiments on muonium complement this work on more conventional atoms.Physica Scripta 09/2006; 2000(T86):21. · 1.03 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: Adjustable magnetic reflection and focusing of an 87Rb Bose–Einstein condensate was achieved using a particularly smooth mirror and a very straightforward apparatus. In this paper, we discuss a simple Thomas–Fermi model and a Monte Carlo method for analysing the bouncing. Both models are in close agreement with the observed condensate evolution. Additionally, the theory predicts very tight condensate focusing, and atomic matterwave diffraction should be observable. The effect of mirror anharmonicities on the condensate focusing is investigated.Journal of Physics B Atomic Molecular and Optical Physics 12/2003; 37(2):485. · 2.03 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We report adjustable magnetic `bouncing' and focusing of a dilute $^{87}$Rb Bose gas. Both the condensate production and manipulation are realised using a particularly straightforward apparatus. The bouncing region is comprised of approximately concentric ellipsoidal magnetic equipotentials with a centre that can be adjusted vertically. We extend, and discuss the limitations of, simple ThomasFermi and MonteCarlo theoretical models for the bouncing, which at present find close agreement with the condensate's evolution. Very strong focusing has been inferred and the observation of atomic matterwave diffraction should be possible. Prospects look bright for applications in matterwave atomoptics, due to the very smooth nature of the mirror.06/2003; 
Article: Destabilization of dark states and optical spectroscopy in Zeemandegenerate atomic systems
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ABSTRACT: We present a general discussion of the techniques of destabilizing dark states in laserdriven atoms with either a magnetic field or modulated laser polarization. We show that the photon scattering rate is maximized at a particular evolution rate of the dark state. We also find that the atomic resonance curve is significantly broadened when the evolution rate is far from this optimum value. These results are illustrated with detailed examples of destabilizing dark states in some commonlytrapped ions and supported by insights derived from numerical calculations and simple theoretical models. Comment: 14 pages, 10 figuresPhysical Review A 11/2001; · 3.04 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: Magnetic videotape is of great interest for trapping and guiding cold atomic vapors, but was hitherto considered unsuitable for manipulating Bose–Einstein condensates (BEC) because of the presumed evolution of gas under vacuum. We have studied the outgassing in vacuum of the most promising tape, Ampex 398 Betacam SP. We find that after cleaning in ethanol and baking for 200h at 100°C the magnetic patterns are undisturbed and the outgassing is remarkably small: 4×1010Torr l s1cm2, due mostly to hydrogen. This makes the tape exceedingly attractive for manipulation of BEC.Applied Physics B 06/2001; 73(1):5154. · 1.78 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We report the reflection and focussing of a BoseEinstein condensate by a new pulsed magnetic mirror. The mirror is adaptive, inelastic, and of extremely high optical quality. The deviations from specularity are less than 0.5 mrad rms, making this the best atomic mirror demonstrated to date. We have also used the mirror to realize the analog of a beamexpander, producing an ultracold collimated fountain of matter waves Comment: 4 pages, 4 figuresPhysical Review A 03/2001; · 3.04 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: A versatile miniature de Broglie waveguide is formed by two parallel currentcarrying wires in the presence of a uniform bias field. We derive a variety of analytical expressions to describe the guide and present a quantum theory to show that it offers a remarkable range of possibilities for atom manipulation on the submicron scale. These include controlled and coherent splitting of the wave function as well as cooling, trapping, and guiding. In particular, we discuss a novel microscopic atom interferometer with the potential to be exceedingly sensitive.Physical Review Letters 03/2001; 86(8):14625. · 7.94 Impact Factor
Publication Stats
1k  Citations  
136.61  Total Impact Points  
Top Journals
Institutions

2008–2014

Los Alamos National Laboratory
 • Applied Modern Physics Group
 • Physics Division
Los Alamos, California, United States


1998–2007

University of Sussex
 Department of Physics and Astronomy
Brighton, England, United Kingdom


1994–2000

Universität Heidelberg
 • Institute of Physical Chemistry
 • Institute of Physics
Heidelberg, BadenWuerttemberg, Germany


1991–1999

Yale University
 Department of Physics
New Haven, Connecticut, United States


1988–1998

University of Oxford
Oxford, England, United Kingdom
