A5064726973- Cold Atom Physics and Bose-Einstein Condensates
- Quantum, superfluid, helium dynamics
- Terahertz technology and applications
- Photonic and Optical Devices
- Calibration and Measurement Techniques
- Plasmonic and Surface Plasmon Research
- Advanced Thermodynamics and Statistical Mechanics
- Thermal Radiation and Cooling Technologies
- Electronic and Structural Properties of Oxides
- Atomic and Subatomic Physics Research
- Spectroscopy and Laser Applications
- Transition Metal Oxide Nanomaterials
- Infrared Target Detection Methodologies
- Magnetic properties of thin films
- Quantum Information and Cryptography
- Spacecraft Design and Technology
- Semiconductor Lasers and Optical Devices
- Superconducting and THz Device Technology
- Molecular Junctions and Nanostructures
- Photonic Crystals and Applications
- Solar Radiation and Photovoltaics
- Plasma Diagnostics and Applications
- Quantum Electrodynamics and Casimir Effect
- Scientific Measurement and Uncertainty Evaluation
- Thermography and Photoacoustic Techniques
Laboratory for Atmospheric and Space Physics
2019-2023
University of Colorado Boulder
2015-2022
University of Colorado System
2020-2021
Joint Institute for Laboratory Astrophysics
2015-2017
University of Alberta
2009-2013
A semiclassical formalism is used to investigate the transistor-like behavior of ultracold atoms in a triple-well potential. Atom current flows from source well, held at fixed chemical potential and temperature, into an empty drain well. In steady-state, gate well located between shown acquire well-defined which are controlled by relative height barriers separating three wells. It that can exceed have lower temperature. electronics terminology, source–gate junction be reverse-biased. As...
The transport of atoms is experimentally studied in a transistor-like triple-well potential consisting narrow gate well surrounded by source and drain wells. Atoms are initially loaded into the with pre-determined temperature chemical potential. Energetic flow from source, across gate, where they removed using resonant light beam. manifestation atom–atom interactions dissipation evidenced rapid population growth vacant well. dynamics shown to depend strongly on feedback parameter determined...
Multi-wall vertically aligned carbon nanotubes (VACNTs) are nearly ideal absorbers due to their exceptionally low reflectance over a broad wavelength range. Integrating VACNTs as bolometer absorbers, however, can be difficult high growth temperature and fragile nature. Despite these challenges, we have microfabricated many different types of VACNT bolometers, ranging from cryogenic optical power primary standards room satellite-based solar irradiance monitors broadband infrared...
An atom-chip-based integrated optical lattice system for cold and ultracold atom applications is presented. The retroreflection optics necessary forming the are bonded directly to chip, enabling a compact robust on-chip system. After achieving Bose-Einstein condensation in magnetic chip trap, we load atoms into vertically oriented 1D demonstrate Landau-Zener tunneling. technology presented here can be readily extended higher dimensional lattices.
The long-term balance between Earth's absorption of solar energy and emission radiation to space is a fundamental climate measurement. Total irradiance (TSI) has been measured from space, uninterrupted, for the past 40 years via series instruments. Compact Irradiance Monitor (CTIM) CubeSat instrument that will demonstrate next-generation technology monitoring total irradiance. It includes novel silicon-substrate room temperature vertically aligned carbon nanotube (VACNT) bolometers. CTIM, an...
We study the monopole (breathing) mode of a finite temperature Bose-Einstein condensate in an isotropic harmonic trap recently developed by Lobser et al. [Nat.~Phys., \textbf{11}, 1009 (2015)]. observe nonexponential collapse amplitude oscillation followed partial revival. This behavior is identified as being due to beating between two eigenmodes system, corresponding in-phase and out-of-phase oscillations condensed noncondensed fractions gas. perform simulations system dynamics using...
Operation of an atomtronic battery is demonstrated where a finite-temperature Bose-Einstein condensate stored in one half double-well potential coupled to initially empty load well that impedance matched by resonant terminator beam. The atom number and temperature the are monitored during discharge cycle, used calculate fundamental properties battery. behavior analyzed according Th\'{e}venin equivalent circuit contains finite internal resistance account for dissipation Battery performance at...
We have developed a planar absolute radiometer for room temperature (PARRoT) that will replace the legacy C-series calorimeter as free-space continuous-wave laser power detector standard at National Institute of Standards and Technology (NIST). This instrument lower combined relative expanded measurement uncertainty ( k = 2) from 0.84 % to 0.13 %. PARRoT’s performance was validated by comparing its response against transfer silicon trap traceable NIST’s primary optimized cryogenic (LOCR)...
Cryogenic buffer-gas beam sources are capable of producing intense beams a wide variety molecules and have number advantages over traditional supersonic expansion sources. In this work, we report on neon matrix isolation study carbon clusters produced with cryogenic source. Carbon created by laser ablation graphite trapped in detected Fourier-transform infrared spectrometer the spectral range 4000-1000 cm-1. Through cluster production as function various system parameters, characterize...
We have designed a microfabricated planar absolute radiometer based on vertically aligned carbon nanotube (VACNT) absorber and an electrical power substitution method. The is to operate at room temperature be capable of measuring laser powers up 300 mW from nm 2300 with expected expanded uncertainty 0.06% (<i>k</i> = 2). capability makes the traceable international system (SI) units. new bolometer currently under construction will replace NIST's 50 year old detector standard for free-space...
We investigate anomalous damping of the monopole mode a non-degenerate 3D Bose gas under isotropic harmonic confinement as recently reported by JILA TOP trap experiment (Lobser et al in preparation). Given realistic confining potential, we develop model for studying collective modes that includes effects anharmonic corrections to potential. By influence these anharmonicities throughout range temperatures and collisional regimes, find is caused joint mechanisms dephasing relaxation....
We demonstrate the terahertz frequency plasmonic characteristics of a metallic/semiconductor interface. The high-frequency transmission radiation through dense ensembles subwavelength sized Cu/CuxO microparticles via near-field coupling localized plasmons is shown to increase when CuxO/Au or CuxO/Pt interface introduced. This finding introduces previously undocumented characteristic interaction with material interfaces, and lays physical groundwork for integration circuits traditional...
Terahertz time-domain spectroscopy has found widespread application due to a number of attractive features including phase-sensitive detection and subpicosecond temporal resolution. Recently, the this technique study ensembles sub-wavelength ferromagnetic particles resulted in observation novel unusual effects. The shape, relative transmission amplitude, time delay broadband terahertz waveform were sensitive magnitude direction an applied magnetic field magnetization states particles....
Currently at NIST, there is an effort to develop a black array of broadband absolute radiometers (BABAR) for far infrared sensing. The linear radiometer elements based on uncooled vanadium oxide (VO<sub>x</sub>) microbolometer pixel technology but with the addition two elements: vertically aligned carbon nanotubes (VACNTs) and electrical substitution heater. Traditional pixels use thermistor film as absorber, which placed quarter wavelength above reflector, typically limiting absorption...
A model for studying atomtronic devices and circuits based on finite temperature Bose-condensed gases is presented. The approach involves numerically solving equations of motion atomic populations coherences, derived using the Bose-Hubbard Hamiltonian Heisenberg picture. resulting cluster expansion truncated at a level giving balance between physics rigor numerical demand mitigation. This allows parametric studies involving time scales that cover both rapid population dynamics relevant to...
An atomtronic transistor circuit is used to realize a driven matterwave oscillator. The consists of Source and Drain regions separated by narrow Gate well. Quasi-steady-state behavior determined from thermodynamic model, which reveals two oscillation threshold regimes. One due the onset Bose-Einstein condensation in well, other appearance negative transresistance regime transistor. thresholds are shown be primarily dependent on potential energy height difference between Gate-Drain...
We present the application of THz plasmonics in imaging dielectric objects embedded metal-filled media. By exploiting time domain information from transmitted pulse, signatures were observed. To enhance low quality images acquired through spectroscopy, a super-resolution image processing technique was applied. It is shown that pulse arrival and phase magnitude compared to integrated instantaneous power provides more detailed object.
Abstract We present the results of a recent, extensive measurement campaign validating traceability solar irradiance record and Earth radiation budget data. The also established future traceability, thus ensuring confidence in continuing climate-data record. total radiometer facility (TRF) at Laboratory for Atmospheric Space Physics (LASP) Boulder, uses liquid helium cooled cryogenic as reference standard validation spaceflight (TSI) instrumentation. In 2008 was directly compared to National...
The Earth radiation budget, a 40-year data record of the balance between solar reaching and amount reflected, emitted from Earth, is key climate for determining whether warming or cooling. need accurate cost-effective space-based measurements driving technology development broadband bolometers linear microbolometer arrays. We describe performance microfabricated 1 x 32 arrays developed this purpose. To accurately measure total outgoing 0.3 μm to over 100 μm, consisting reflected shortwave...