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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

High-angular-momentum Rydberg states in a room-temperature vapor cell for dc electric-field sensing

We prepare and analyze Rydberg states with orbital quantum numbers ℓ ≤ 6 using three-optical-photon electromagnetically induced transparency (EIT) and radio frequency (rf) dressing, and employ the high- ℓ states in electric-field sensing. Rubidium-85 atoms in a room-temperature vapor cell are first promoted into the 25 F 5 / 2 state via Rydberg-EIT with three infrared laser beams. Two rf dressing fields then (near-)resonantly couple the 25 F , 25 H ( ℓ = 5 ) , and 25 I ( ℓ = 6 ) Rydberg states. The dependence of the rf-dressed Rydberg-state level structure on rf powers, rf and laser frequencies is characterized using EIT. Furthermore, we discuss the principles of dc-electric-field sensing using high- ℓ Rydberg states and experimentally demonstrate the method using test electric fields of ≲ 50 V/m induced via photo-illumination of the vapor-cell wall. We measure the highly nonlinear dependence of the dc-electric-field strength on the power of the photo-illumination laser. Numerical calculations, which reproduce our experimental observations well, elucidate the underlying physics. Our paper is relevant to high-precision spectroscopy of high- ℓ Rydberg states, Rydberg-atom-based electric-field sensing, and plasma electric-field diagnostics. Published by the American Physical Society 2024

Duspayev, Alisher (ORCID:0000000153225762)↗
DOE OSTI2024

Mitigating Scattering in a Quantum System Using Only an Integrating Sphere

Strong quantum correlated sources are essential but delicate resources for quantum information science and engineering protocols. Decoherence and loss are the two main disruptive processes that lead to the loss of nonclassical behavior in quantum correlations. In quantum systems, scattering can contribute to both decoherence and loss. In this work, we present an experimental scheme capable of significantly mitigating the adverse impact of scattering in quantum systems. Our quantum system is composed of a two-mode squeezed light generated with the four-wave-mixing process in hot rubidium vapor and a scatterer is introduced to one of the two modes. An integrating sphere is then placed after the scatterer to recollect the scattered photons. We use mutual information between the two modes as the measure of quantum correlations and demonstrate a 47.5% mutual information recovery from scattering, despite an enormous photon loss of greater than 85%. Our scheme is the very first step toward recovering quantum correlations from disruptive random processes and thus has the potential to bridge the gap between proof-of-principle demonstrations and practical real-world implementations of quantum protocols. Published by the American Physical Society 2024

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2022

Evaluating Recombination Mechanisms in RbF Treated Cu(In${}_\mathrm{x}$Ga$_\mathrm{1-x}$)Se$_{2}$ Solar Cells

Rubidium fluoride (RbF) postdeposition treatment (PDT) has been shown to improve the performance of Cu(In x Ga 1-x )Se 2 (CIGS) photovoltaic devices. Here, in this study, temperature-dependent current voltage (JVT) and time-resolved photoluminescence (TRPL) experiments were combined with modeling using the solar cell capacitance simulator (SCAPS) computer code to investigate the effect of the RbF PDT. Two devices, one as-deposited and one with RbF PDT, were deposited by a three stage coevaporation process. JVT measurements suggest the dominant recombination mechanism may be tunneling-enhanced recombination via bandtail states, but that defect states in the bandgap can also be important. RbF PDT is shown to decrease the characteristic energy of the bandtails. TRPL data show an increase in the minority carrier lifetime after RbF PDT, leading to an improved open-circuit voltage. SCAPS modeling indicates that the dominant recombination mechanism is dependent on the specific defect makeup of a device, suggesting that small changes in processing conditions can impact device behavior. This explains the observation that, for some devices, defect states in the gap dominate while others, as is the case here, appear to be dominated by bandtails.

14 SOLAR ENERGY↗
DOE OSTI2024

Improved VOC in RbF-Treated Cu(In,Ga)Se2 Solar Cells via Passivation of Recombination Centers

Cu(In,Ga)Se 2 (CIGS) solar cells have benefited in recent years from the addition of heavy alkali elements, such as Rb, which increase the solar cell open-circuit voltage ( V OC ). To investigate the source of this improvement, here, we compare samples with and without Rb to perform a quantitative comparison of electronic defects and minority carrier lifetime. Deep-level transient and optical spectroscopy measurements were performed on two sets of rubidium fluoride (RbF)-treated and untreated CIGS, and three distinct traps were identified regardless of RbF treatment. The RbF treatment was found to reduce the concentration of the H2 trap, which was previously found to act as a recombination center and is located preferentially at CIGS grain boundaries. Time-resolved photoluminescence measurements showed an increase in effective lifetime after RbF and nearly all lifetime improvement resulted from reductions in bulk recombination. The observed V OC improvement is well correlated with increased minority carrier lifetime and acceptor concentration, which led to increases and decreases in electron and hole quasi-Fermi levels, respectively.

Cu(In Ga)Se2 (CIGS)↗
DOE OSTI2021

A passively pumped vacuum package sustaining cold atoms for more than 200 days

Compact cold-atom sensors depend on vacuum technology. One of the major limitations to miniaturizing these sensors is the active pumps—typically ion pumps—that are required to sustain the low pressure needed for laser cooling. Although passively pumped chambers have been proposed as a solution to this problem, technical challenges have prevented successful operation at the levels needed for cold-atom experiments. The authors present the first demonstration of a vacuum package successfully independent of ion pumps for more than a week; their vacuum package is capable of sustaining a cloud of cold atoms in a magneto-optical trap (MOT) for greater than 200 days using only non-evaporable getters and a rubidium dispenser. Measurements of the MOT lifetime indicate that the package maintains a pressure of better than 2×10−7 Torr. This result will significantly enable the development of compact atomic sensors, including those sensitive to magnetic fields, where the absence of an ion pump will be advantageous.

Little, Bethany J. (ORCID:0000000332892798)↗
DOE OSTI2024

High-performance silicon photonic single-sideband modulators for cold-atom interferometry

The laser system is the most complex component of a light-pulse atom interferometer (LPAI), controlling frequencies and intensities of multiple laser beams to configure quantum gravity and inertial sensors. Its main functions include cold-atom generation, state preparation, state-selective detection, and generating a coherent two-photon process for the light-pulse sequence. To achieve substantial miniaturization and ruggedization, we integrate key laser system functions onto a photonic integrated circuit. Our study focuses on a high-performance silicon photonic suppressed-carrier single-sideband (SC-SSB) modulator at 1560 nanometers, capable of dynamic frequency shifting within the LPAI. By independently controlling radio frequency (RF) channels, we achieve 30-decibel carrier suppression and unprecedented 47.8-decibel sideband suppression at peak conversion efficiency of –6.846 decibels (20.7%). We investigate imbalances in both amplitudes and phases between the RF signals. Using this modulator, we demonstrate cold-atom generation, state-selective detection, and atom interferometer fringes to estimate gravitational acceleration, g ≈ 9.77 ± 0.01 meters per second squared, in a rubidium ( 87 Rb) atom system.

47 OTHER INSTRUMENTATION↗
DOE OSTI2024

Lunar soil record of atmosphere loss over eons

The Moon has a tenuous atmosphere produced by space weathering. The short-lived nature of the atoms surrounding the Moon necessitates continuous replenishment from lunar regolith through mechanisms such as micrometeorite impacts, ion sputtering, and photon-stimulated desorption. Despite advances, previous remote sensing and space mission data have not conclusively disentangled the contributions of these processes. Using high-precision potassium (K) and rubidium (Rb) isotopic analyses of lunar soils from the Apollo missions, our study sheds light on the lunar surface-atmosphere evolution over billions of years. The observed correlation between K and Rb isotopic ratios (δ 87 Rb = 0.17 δ 41 K) indicates that, over long timescales, micrometeorite impact vaporization is the primary source of atoms in the lunar atmosphere.

Science & Technology - Other Topics↗
DOE OSTI2025

Interleaved dual-species arrays of single atoms using a passive optical element and one trapping laser

We demonstrate trapping of individual rubidium (Rb) and cesium (Cs) atoms in an interleaved array of bright tweezers and dark bottle-beam traps, using a microfabricated optical element illuminated by a single-laser beam and a 4f system with spatial filtering. Our approach exploits the opposite-sign dynamic polarizabilities of Rb and Cs, ensuring that each species is exclusively trapped in either bright or dark sites. The passive optical mask creates optimal trap depths for both species using three transmittance levels while minimizing the optical phase difference, implemented using a variable-thickness absorbing layer of amorphous germanium. This trapping architecture achieves atom loading rates close to 50% while reducing system complexity compared to conventional methods using active optoelectronic components and/or multiple-laser wavelengths.

Fang, Chengyu [Univ. of Wisconsin, Madison, WI (Un↗
DOE OSTI2023

Mid-circuit correction of correlated phase errors using an array of spectator qubits

Scaling up invariably error-prone quantum processors is a formidable challenge. Although quantum error correction ultimately promises fault-tolerant operation, the required qubit overhead and error thresholds are daunting. In a complementary proposal, colocated, auxiliary “spectator” qubits act as in situ probes of noise and enable real-time, coherent corrections of data qubit errors. We used an array of cesium spectator qubits to correct correlated phase errors on an array of rubidium data qubits. By combining in-sequence readout, data processing, and feedforward operations, these correlated errors were suppressed within the execution of the quantum circuit. The protocol is broadly applicable to quantum information platforms and establishes key tools for scaling neutral-atom quantum processors: mid-circuit readout of atom arrays, real-time processing and feedforward, and coherent mid-circuit reloading of atomic qubits.

Science & Technology - Other Topics↗
DOE OSTI2024

Quantum interference in atom-exchange reactions

Chemical reactions, in which bonds break and form, are highly dynamic quantum processes. A fundamental question is whether coherence can be preserved in chemical reactions and then harnessed to generate entangled products. Here we investigated this question by studying the 2KRb → K 2 + Rb 2 reaction at 500 nanokelvins, focusing on the nuclear spin degrees of freedom. We prepared the initial nuclear spins in KRb (potassium-rubidium) in an entangled state by lowering the magnetic field to where the spin-spin interaction dominates and characterized the preserved coherence in nuclear spin wave function after the reaction. We observed an interference pattern that is consistent with full coherence at the end of the reaction, suggesting that entanglement prepared within the reactants could be redistributed through the atom-exchange process.

Science & Technology - Other Topics↗
DOE OSTI2025

Single-Photon Generation: Materials, Techniques, and the Rydberg Exciton Frontier

Due to their quantum nature, single-photon emitters (SPE) generate individual photons in bursts or streams. They are paramount in emerging quantum technologies such as quantum key distribution, quantum repeaters, and measurement-based quantum computing. Many such systems have been reported in the last three decades, from rubidium atoms coupled to cavities to semiconductor quantum dots and color centers implanted in waveguides. This review article highlights different solid-state and atomic systems with on-demand and controlled single-photon generation. We discuss and compare the performance metrics, such as purity and indistinguishability, for these sources and evaluate their potential for different applications. Finally, a new potential single-photon source, based on the Rydberg exciton in solid-state metal oxide thin films, is introduced, where we discuss its promising features and unique advantages in fabricating quantum chips for quantum photonic applications.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2020

Materials Data on RbAuC2 by Materials Project

RbAuC2 crystallizes in the tetragonal P4/mmm space group. The structure is one-dimensional and consists of one rubidium molecule and one AuC2 ribbon oriented in the (0, 0, 1) direction. In the AuC2 ribbon, Au1- is bonded in a linear geometry to two equivalent C atoms. Both Au–C bond lengths are 2.00 Å. C is bonded in a linear geometry to one Au1- and one C atom. The C–C bond length is 1.25 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on RbBSe3 by Materials Project

RbBSe3 crystallizes in the monoclinic P2_1/c space group. The structure is one-dimensional and consists of four rubidium molecules and two BSe3 ribbons oriented in the (1, 0, 0) direction. In each BSe3 ribbon, B3- is bonded to four Se+0.67+ atoms to form corner-sharing BSe4 tetrahedra. There are two shorter (2.06 Å) and two longer (2.09 Å) B–Se bond lengths. There are three inequivalent Se+0.67+ sites. In the first Se+0.67+ site, Se+0.67+ is bonded in a single-bond geometry to one B3- atom. In the second Se+0.67+ site, Se+0.67+ is bonded in a water-like geometry to two equivalent B3- atoms. In the third Se+0.67+ site, Se+0.67+ is bonded in a single-bond geometry to one B3- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on RbNa2Ge17 by Materials Project

RbNa2Ge17 crystallizes in the cubic Fd-3m space group. The structure is three-dimensional and consists of eight rubidium molecules and one Na2Ge17 framework. In the Na2Ge17 framework, Na is bonded in a 8-coordinate geometry to twenty Ge atoms. There are a spread of Na–Ge bond distances ranging from 3.43–3.62 Å. There are three inequivalent Ge sites. In the first Ge site, Ge is bonded to two equivalent Na and four Ge atoms to form a mixture of edge and corner-sharing GeNa2Ge4 tetrahedra. There are one shorter (2.54 Å) and three longer (2.56 Å) Ge–Ge bond lengths. In the second Ge site, Ge is bonded in a 4-coordinate geometry to three equivalent Na and four Ge atoms. The Ge–Ge bond length is 2.53 Å. In the third Ge site, Ge is bonded in a body-centered cubic geometry to four equivalent Na and four equivalent Ge atoms.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Rb3Ir(NO2)6 by Materials Project

Rb(RbO6)2Ir(N2)3 crystallizes in the cubic Fm-3m space group. The structure is three-dimensional and consists of twenty-four ammonia molecules, four iridium molecules, four rubidium molecules, and one RbO6 framework. In the RbO6 framework, Rb1+ is bonded in a distorted q4 geometry to twelve equivalent O2- atoms. All Rb–O bond lengths are 2.90 Å. O2- is bonded in a 3-coordinate geometry to two equivalent Rb1+ and one O2- atom. The O–O bond length is 1.29 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Rb2PdSe16 by Materials Project

RbRbPdSe16 crystallizes in the tetragonal P-4b2 space group. The structure is three-dimensional and consists of two rubidium molecules and one RbPdSe16 framework. In the RbPdSe16 framework, Rb1+ is bonded in a distorted cuboctahedral geometry to twelve Se+0.38- atoms. There are eight shorter (3.96 Å) and four longer (4.09 Å) Rb–Se bond lengths. Pd4+ is bonded in a square co-planar geometry to four equivalent Se+0.38- atoms. All Pd–Se bond lengths are 2.47 Å. There are four inequivalent Se+0.38- sites. In the first Se+0.38- site, Se+0.38- is bonded in a 3-coordinate geometry to one Rb1+ and two Se+0.38- atoms. There are one shorter (2.40 Å) and one longer (2.42 Å) Se–Se bond lengths. In the second Se+0.38- site, Se+0.38- is bonded in a 1-coordinate geometry to one Rb1+, one Pd4+, and one Se+0.38- atom. The Se–Se bond length is 2.39 Å. In the third Se+0.38- site, Se+0.38- is bonded in a distorted water-like geometry to two Se+0.38- atoms. The Se–Se bond length is 2.41 Å. In the fourth Se+0.38- site, Se+0.38- is bonded in a 3-coordinate geometry to one Rb1+ and two Se+0.38- atoms. The Se–Se bond length is 2.40 Å.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on Rb2SbBr6 by Materials Project

(Rb)2SbBr6 crystallizes in the tetragonal I4_1/amd space group. The structure is zero-dimensional and consists of sixteen rubidium molecules and eight SbBr6 clusters. In each SbBr6 cluster, Sb2- is bonded in an octahedral geometry to six Br atoms. There are four shorter (2.76 Å) and two longer (2.77 Å) Sb–Br bond lengths. There are two inequivalent Br sites. In the first Br site, Br is bonded in a single-bond geometry to one Sb2- atom. In the second Br site, Br is bonded in a single-bond geometry to one Sb2- atom.

36 MATERIALS SCIENCE↗
DOE OSTI2020

Materials Data on RbH4SNO4 by Materials Project

RbNH4SO4 is Iron carbide-derived structured and crystallizes in the orthorhombic Pnma space group. The structure is zero-dimensional and consists of four ammonium molecules and four rubidium hydrogen sulfate molecules.

36 MATERIALS SCIENCE↗