L. A. Orozco

National Institute of Standards and Technology, GAI, Maryland, United States

Are you L. A. Orozco?

Claim your profile

Publications (199)364.43 Total impact

  • IEEE Transactions on Applied Superconductivity 06/2015; 25(3):1-5. DOI:10.1109/TASC.2014.2379628 · 1.32 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We measure the quantum speed of the state evolution of the field in a weakly-driven optical cavity QED system. To this end, the mode of the electromagnetic field is considered as a quantum system of interest with a preferential coupling to a tunable environment: the atoms. By controlling the environment, i.e., changing the number of atoms coupled to the optical cavity mode, an environment assisted speed-up is realized: the quantum speed of the state re-population in the optical cavity increases with the coupling strength between the optical cavity mode and this non-Markovian environment (the number of atoms).
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We experimentally demonstrate optical trapping of 87Rb atoms using a two-color evanescent field around an optical nanofiber. In our trapping geometry, a blue-detuned traveling wave whose polarization is nearly parallel to the polarization of a red-detuned standing wave produce significant vector light shifts that lead to broadening of the absorption profile of a near-resonant beam at the trapping site. A model that includes scalar, vector, and tensor light shifts of the probe transition $5S_{1/2}$-$5P_{3/2}$ from the trapping beams; weighted by the temperature-dependent position of the atoms in the trap qualitatively describe the observed asymmetric profile, and explained differences with previous experiments that used Cs atoms. The model provides a consistent way to extract the number of atoms in the trap.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We demonstrate a new technique to prepare an offline source of francium for trapping in a magneto-optical trap. Implanting a radioactive beam of $^{225}$Ac, $t_{1/2} = 9.920(3)$ days, in a foil, allows use of the decay products, i.e.$^{221}$Fr, $t_{1/2} = 288.0(4)$ s. $^{221}$Fr is ejected from the foil by the $\alpha$ decay of $^{225}$Ac. This technique is compatible with the online accumulation of a laser-cooled atomic francium sample for a series of planned parity non-conservation measurements at TRIUMF. We obtain a 34% release efficiency for $^{221}$Fr from the recoil source based on particle detector measurements. We find that laser cooling operation with the source is $8^{+10}_{-5}$ times less efficient than from a mass-separated ion beam of $^{221}$Fr in the current geometry. While the flux of this source is two to three orders of magnitude lower than typical francium beams from ISOL facilities, the source provides a longer-term supply of francium for offline studies.
    Journal of Instrumentation 09/2014; 9(10). DOI:10.1088/1748-0221/9/10/P10013 · 1.53 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We present a procedure for reproducibly fabricating ultrahigh transmission optical nanofibers (530 nm diameter and 84 mm stretch) with single-mode transmissions of 99.95 $ \pm$ 0.02%, which represents a loss from tapering of 2.6 $\,\times \,$ 10$^{-5}$ dB/mm when normalized to the entire stretch. When controllably launching the next family of higher-order modes on a fiber with 195 mm stretch, we achieve a transmission of 97.8 $\pm$ 2.8%, which has a loss from tapering of 5.0 $\,\times \,$ 10$^{-4}$ dB/mm when normalized to the entire stretch. Our pulling and transfer procedures allow us to fabricate optical nanofibers that transmit more than 400 mW in high vacuum conditions. These results, published as parameters in our previous work, present an improvement of two orders of magnitude less loss for the fundamental mode and an increase in transmission of more than 300% for higher-order modes, when following the protocols detailed in this paper. We extract from the transmission during the pull, the only reported spectrogram of a fundamental mode launch that does not include excitation to asymmetric modes; in stark contrast to a pull in which our cleaning protocol is not followed. These results depend critically on the pre-pull cleanliness and when properly following our pulling protocols are in excellent agreement with simulations.
  • [Show abstract] [Hide abstract]
    ABSTRACT: We present a procedure for reproducibly fabricating ultrahigh transmission optical nanofibers (530 nm diameter and 84 mm stretch) with single-mode transmissions of 99.95 $ \pm$ 0.02%, which represents a loss from tapering of 2.6 $\,\times \,$ 10$^{-5}$ dB/mm when normalized to the entire stretch. When controllably launching the next family of higher-order modes on a fiber with 195 mm stretch, we achieve a transmission of 97.8 $\pm$ 2.8%, which has a loss from tapering of 5.0 $\,\times \,$ 10$^{-4}$ dB/mm when normalized to the entire stretch. Our pulling and transfer procedures allow us to fabricate optical nanofibers that transmit more than 400 mW in high vacuum conditions. These results, published as parameters in our previous work, present an improvement of two orders of magnitude less loss for the fundamental mode and an increase in transmission of more than 300% for higher-order modes, when following the protocols detailed in this paper. We extract from the transmission during the pull, the only reported spectrogram of a fundamental mode launch that does not include excitation to asymmetric modes; in stark contrast to a pull in which our cleaning protocol is not followed. These results depend critically on the pre-pull cleanliness and when properly following our pulling protocols are in excellent agreement with simulations.
    AIP Advances 04/2014; 4(6). DOI:10.1063/1.4879799 · 1.59 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We report on the successful commissioning of the Francium Trapping Facility at TRIUMF. Large laser-cooled samples of francium are produced from a francium ion beam delivered by the ISAC radioactive ion beam facility. The ion beam is neutralized on an yttrium foil, which is subsequently heated to transfer the atoms into the magneto-optical trapping region. We have successfully trapped $^{207}$Fr, $^{209}$Fr and $^{221}$Fr, with a maximum of $2.5 \times 10^5$ $^{209}$Fr atoms. The neutral cold atoms will be used in studies of the weak interaction through measurements of atomic parity non-conservation.
    Journal of Instrumentation 12/2013; 8(12). DOI:10.1088/1748-0221/8/12/P12006 · 1.53 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We present an experimental and theoretical study of the energy transfer between modes during the tapering process of an optical nanofiber through spectrogram analysis. The results allow optimization of the tapering process, and we measure transmission in excess of 99.95% for the fundamental mode. We quantify the adiabaticity condition through calculations and place an upper bound on the amount of energy transferred to other modes at each step of the tapering, giving practical limits to the tapering angle.
    Journal of the Optical Society of America A 11/2013; 30(11):2361-71. DOI:10.1364/JOSAA.30.002361 · 1.67 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Conditional measurements on the undriven mode of a two-mode cavity QED system prepare a coherent superposition of ground states which generate quantum beats. The continuous system drive induces decoherence through the phase interruptions from Rayleigh scattering, which manifests as a decrease of the beat amplitude and an increase of the frequency of oscillation. We report recent experiments that implement a simple feedback mechanism to protect the quantum beat. We continuously drive the system until a photon is detected, heralding the presence of a coherent superposition. We then turn off the drive and let the superposition evolve in the dark, protecting it against decoherence. At a later time we reinstate the drive to measure the amplitude, phase, and frequency of the beats. The amplitude can increase by more than fifty percent, while the frequency is unchanged by the feedback.
    The European Physical Journal Conferences 09/2013; 57. DOI:10.1051/epjconf/20135703005
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The grating magneto-optical trap (GMOT) requires only one beam and three planar diffraction gratings to form a cloud of cold atoms above the plane of the diffractors. Despite the complicated polarization arrangement, we demonstrate sub-Doppler cooling of 87Rb atoms to a temperature of 7.6(0.6) uK through a multi-stage, far-detuned GMOT in conjunction with optical molasses. A decomposition of the electric field into polarization components for this geometry does not yield a mapping onto standard sub-Doppler laser-cooling configurations. With numerical simulations, we find that the polarization composition of the GMOT optical field, which includes sigma- and pi-polarized light, does produce sub-Doppler temperatures.
    Journal of the Optical Society of America B 09/2013; 30(11). DOI:10.1364/JOSAB.30.002869 · 1.81 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Hybrid quantum systems can be formed that combine the strengths of multiple platforms while avoiding the weaknesses. Here we report on progress toward a hybrid quantum system of neutral atom spins coupled to superconducting qubits. We trap laser-cooled rubidium atoms in the evanescent field of an ultrathin optical fiber, which will be suspended a few microns above a superconducting circuit that resonates at the hyperfine frequency of the Rb atoms, allowing magnetic coupling between the atoms and superconductor. As this will be done in a dilution refrigerator environment, the technical demands on the optical fiber is severe. We have developed and optimized a tapered fiber fabrication system, achieving optical transmission in excess of 99.95% , and fibers that can sustain 400 mW of optical power in a UHV environment. We have also optimized tapered fibers that can support higher order optical modes with high transmission (> 97%), which may be useful for different optical potential geometries. We have developed an in-situ tunable high-Q superconducting microwave resonator that can be tuned to within the resonator linewidth of the 6.8 GHz frequency of the Rb hyperfine transition.
    Proceedings of SPIE - The International Society for Optical Engineering 09/2013; DOI:10.1117/12.2024362 · 0.20 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Optical nanofibers confine light to subwavelength scales, and are of interest for the design, integration, and interconnection of nanophotonic devices. Here we demonstrate high transmission (> 97%) of the first family of excited modes through a 350 nm radius fiber, by appropriate choice of the fiber and precise control of the taper geometry. We can design the nanofibers so that these modes propagate with most of their energy outside the waist region. We also present an optical setup for selectively launching these modes with less than 1% fundamental mode contamination. Our experimental results are in good agreement with simulations of the propagation. Multimode optical nanofibers expand the photonic toolbox, and may aid in the realization of a fully integrated nanoscale device for communication science, laser science or other sensing applications.
    Optics Express 08/2013; 21(15). DOI:10.1364/OE.21.018325 · 3.53 Impact Factor
  • D. Sheng, J. Zhang, L. A. Orozco
    [Show abstract] [Hide abstract]
    ABSTRACT: Blue-detuned dipole traps and their ability to preserve atomic coherences are interesting for precision measurement applications. In this paper, we present experimental studies on the differential ac Stark shift of the ground-state hyperfine splitting in 87Rb atoms confined in a dynamic blue-detuned dipole trap. We systematically study the power and detuning effects on the Rabi resonance frequency (differential ac Stark shift) and its linewidth (coherence) and find that their performance is compatible with future parity violation experiments in Fr.
    Physical Review A 06/2013; 87(6):63412-. DOI:10.1103/PhysRevA.87.063412 · 2.99 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We present the current status of the Francium Trapping Facility at ISAC at TRIUMF. The facility will enable future experiments on the weak interaction with measurements of atomic parity non-conservation laser-cooled samples of artificially produced francium. These experiments require a precisely controlled environment, which the facility is designed to provide. The facility has been constructed and is being prepared for a series of commissioning runs.
    04/2013; DOI:10.1063/1.4802385
  • [Show abstract] [Hide abstract]
    ABSTRACT: We present a method for measuring the nuclear anapole in a string of francium isotopes. The anapole is a parity non-conserving electromagnetic moment that enables parity-forbidden transitions between ground state hyperfine levels of an atom. The experiment is run by the FrPNC collaboration and relies on a beam of artificially-produced francium from the ISAC facility at TRIUMF.
    Hyperfine Interactions 03/2013; 214(1-3). DOI:10.1007/s10751-013-0797-6 · 0.21 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: To create a hybrid quantum system, we plan to trap neutral atoms in the evanescent optical field from an optical nanofiber and move them to within a few microns above a SQUID in a dilution refrigerator that operates at 10 mK. A key component in this experiment is a long section (10 cm) of optical fiber with a uniform diameter of about 500 nm, sufficiently small that the light propagates on the surface of the fiber as an evanescent wave. We have produced suitably long nanofibers with carefully tapered sections that allow matching of the optical field in the tapered and untapered sections. We have achieved more than 99.95% transmission of the fundamental mode and good evanescent fields; as well as more than 85% transmission when using higher order modes. A single-beam, magneto-optical trap that uses optical gratings captures and cools atoms to load on the nanofiber to work at cryogenic temperatures. We will present our technique, key results, and progress towards trapping atoms on the fibers.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We implement a simple feedback mechanism on a two-mode cavity QED system to preserve the Zeeman coherence of a ground state superposition that generates quantum beats on the second-order correlation function. Our investigation includes theoretical and experimental studies that show how to prevent a shift away from the Larmor frequency and associated decoherence caused by Rayleigh scattering. The protocol consists of turning off the drive of the system after the detection of a first photon and letting it evolve in the dark. Turning the drive back on after a pre-set time reveals a phase accumulated only from Larmor precession, with the amplitude of the quantum beat more than a factor of two larger than with continuous drive.
    New Journal of Physics 01/2013; 15(1). DOI:10.1088/1367-2630/15/1/013017 · 3.67 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The spontaneous creation and persistence of ground-state coherence in an ensemble of intracavity Rb atoms has been observed as a quantum beat. Our system realizes a quantum eraser, where the detection of a first photon prepares a superposition of ground-state Zeeman sublevels, while detection of a second erases the stored information. Beats appear in the time-delayed photon-photon coincidence rate (intensity correlation function). We study the beats theoretically and experimentally as a function of system parameters, and find them remarkably robust against perturbations such as spontaneous emission. Although beats arise most simply through single-atom-mediated quantum interference, scattering pathways involving pairs of atoms interfere also in our intracavity experiment. We present a detailed model which identifies all sources of interference and accounts for experimental realities such as imperfect pre-pumping of the atomic beam, cavity birefringence, and the transit of atoms across the cavity mode.
    Physical Review A 11/2012; 86(5). DOI:10.1103/PhysRevA.86.053816 · 2.99 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Francium is an excellent system to study the nuclear weak force due to its large nucleus and relatively simple atomic structure. The FrPNC experiment has a facility to produce cold trapped atomic francium samples for parity non-conservation studies. We are preparing to measure both the nuclear spin independent and dependent parts of the weak interaction in francium. The first one gives information about weak neutral currents at low energies, while the second one is sensitive to weak interactions between nucleons. We present the current status of the experiment.
    Journal of Physics Conference Series 09/2012; 387(1):2004-. DOI:10.1088/1742-6596/387/1/012004
  • [Show abstract] [Hide abstract]
    ABSTRACT: Nanofibers are a promising tool for hybrid systems of atomtronics and quantum information. We present the construction and characterization protocol that allows us to reliably produce nanofibers with a waist up to 10 cm in length and down to 500 nm in diameter operating around 780 nm (Rb D2 line). By controlling the angle in the tapered region at chosen radii, we can excite higher order modes in the fiber and observe their beating while monitoring the transmission during the pull. To reach the adiabatic regime, thus minimizing transmission losses in the fiber, we can reduce the taper angle in the critical excitation regions. Using this technique we can minimize the length of our taper region for given loss constraints.

Publication Stats

2k Citations
364.43 Total Impact Points

Institutions

  • 2007–2015
    • National Institute of Standards and Technology
      GAI, Maryland, United States
    • Miami University
      • Department of Physics
      Oxford, OH, United States
  • 2008–2013
    • Loyola University Maryland
      • Department of Physics
      Baltimore, Maryland, United States
  • 2004–2013
    • University of Maryland, College Park
      • Department of Physics
      Maryland, United States
    • University of Toronto
      Toronto, Ontario, Canada
  • 2011
    • University of Auckland
      • Department of Physics
      Auckland, Auckland, New Zealand
  • 1993–2006
    • State University of New York
      New York City, New York, United States
  • 2005
    • University of Arkansas
      • Department of Physics
      Fayetteville, AR, United States
  • 1995–2004
    • Stony Brook University
      • Department of Physics and Astronomy
      Stony Brook, New York, United States
  • 2000
    • University of Oregon
      • Department of Physics
      Eugene, OR, United States
    • Universität Ulm
      Ulm, Baden-Württemberg, Germany
  • 1993–1999
    • SUNY Ulster
      Кингстон, New York, United States
  • 1970–1995
    • University of Texas at Austin
      • Department of Physics
      Austin, Texas, United States
  • 1987
    • Southern Methodist University
      • Department of Physics
      Dallas, Texas, United States