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Results for “Quantum interference”

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 775 records · Page 43
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Dynamical interference in the vibronic bond breaking reaction of HCO

First-principles treatments of quantum molecular reaction dynamics have reached the level of quantitative accuracy even in cases with strong non–Born-Oppenheimer effects. This achievement permits the interpretation of puzzling experimental phenomena related to dynamics governed by multiple coupled potential energy surfaces. We present a combined experimental and theoretical study of the photodissociation of formyl radical (HCO). Oscillations observed in the distribution of product states are found to arise from the interference of matter waves—a manifestation analogous to Young’s double-slit experiment.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2015

Nanostructure surface patterning of GaN thin films and application to AlGaN/AlN multiple quantum wells: A way towards light extraction efficiency enhancement of III-nitride based light emitting diodes

Enhanced light extraction efficiency was demonstrated on nanostructure patterned GaN and AlGaN/AlN Multiple-Quantum-Well (MQW) structures using mass production techniques including natural lithography and interference lithography with feature size as small as 100 nm. Periodic nanostructures showed higher light extraction efficiency and modified emission profile compared to non-periodic structures based on integral reflection and angular-resolved transmission measurement. Light extraction mechanism of macroscopic and microscopic nanopatterning is discussed, and the advantage of using periodic nanostructure patterning is provided. An enhanced photoluminescence emission intensity was observed on nanostructure patterned AlGaN/AlN MQW compared to as-grown structure, demonstrating a large-scale and mass-producible pathway to higher light extraction efficiency in deep-ultra-violet light-emitting diodes.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2017

Forced field ionization of Rydberg states for the production of monochromatic beams

In this work, we study Rydberg ionization in an electric field in order to produce monochromatic ion and electron beams. We present an experimental study of the photoexcitation and ionization of high quantum-defect states, using excitation from the 7s state in cesium to Rydberg states in the presence of a uniform electric field. Such states can exhibit complex ionization behavior, for instance, highly localized growth in the ionization rate due to interference effects. The data are well reproduced by the WKB quantum-defect and frame transformation methods with no adjustable parameters. This indicates that large changes in the Rydberg ionization rate from small changes in electric field are possible when a nearly stable state crosses a more unstable state. A fast variation of the ionization rate with electric field allows for the production of beams with very low energy dispersion. We develop a simple two-level model to predict the voltage and spatial resolution that would occur when atoms are prepared in a state with such sharp ionization in electric field. This confirms that Rydberg forced ionization in an electric field presents a pathway for the production of high-brightness, highly monochromatic ion and electron beams.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2011

Dephasing of strong coupling in the non-linear regime

We study the effect of pure dephasing on the strong-coupling of a two-level system (typically, a quantum dot) with the single mode of a microcavity. Whereas dephasing merely broadens the line in the linear regime, it results in a new spectral shape when transitions between higher manifolds of the Jaynes-Cummings ladder are involved, namely, a triplet, that we show does not imply weak-coupling. Higher excitation brings the system into lasing. Description of this intermediate triplet allows to demonstrate quantum nonlinearities even in noisy systems and to measure the magnitude of dephasing.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2015

Effects of electron interference on temperature dependent transport properties of two dimensional electron gas at MgZnO/ZnO interfaces

We report the effects of electron interference on temperature dependent transport properties of two dimensional electron gas (2DEG) confined at the interface in polycrystalline MgZnO/ZnO heterostructures grown by pulsed laser deposition on c-alumina substrates. On increasing Mg concentration in the MgZnO layer, the sheet electron concentration was found to increase and the sheet resistance was found to decrease. In addition, the electron concentration and mobility were almost temperature independent in the range from 4.2 to 300 K, indicating the formation of 2DEG at the interface. The temperature dependent resistivity measurements showed a negative temperature coefficient of resistivity at low temperatures together with negative magnetoresistance. These were found to be caused by electron interference effects, and the experimental data could be explained using the models of quantum corrections to conductivity.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

Phase sensitive Raman process with correlated seeds

A phase sensitive Raman scattering was experimentally demonstrated by injecting a Stokes light seed into an atomic ensemble, whose internal state is set in such a way that it is coherent with the input Stokes seed. Such phase sensitive characteristic is a result of interference effect due to the phase correlation between the injected Stokes light field and the internal state of the atomic ensemble in the Raman process. Furthermore, the constructive interference leads to a Raman efficiency larger than other kinds of Raman processes such as stimulated Raman process with Stokes seed injection alone or uncorrelated light-atom seeding. It may find applications in precision spectroscopy, quantum optics, and precise measurement.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2014

Optics learning through affordable kit

An affordable kit which helps to understand some of the optical phenomena qualitatively and quantitatively is presented in this paper. It supplements optics taught in classes. The kit consists of equipments which are available in the market at nominal cost such as laser pointer, lenses, glass plates, razor blades, coins, ball bearing etc. Experiments which come under wave optics (interference and diffraction) and ray optics (reflection and refraction) are explained using this kit.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2011

Enhancement of measurement sensitivity in the formation of shear interferograms of transparent plates with small residual wedging

We have proposed a method for increasing the sensitivity of measurements of the wedge angle in transparent plates. The method is based on formation of the holographic shear interferograms using a combination of 180 Degree-Sign rotation of the plate with byturn adjustment of interferograms in its images to an infinitely wide fringe. The sensitivity enhancement is due to the increased number of interference fringes in the observed images of the wedged plate, which favours the reduction of the measurement error during optical processing of the obtained interferograms. Data on the experimental validation of the proposed method are presented.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2014

Detector-device-independent quantum key distribution

Recently, a quantum key distribution (QKD) scheme based on entanglement swapping, called measurement-device-independent QKD (mdiQKD), was proposed to bypass all measurement side-channel attacks. While mdiQKD is conceptually elegant and offers a supreme level of security, the experimental complexity is challenging for practical systems. For instance, it requires interference between two widely separated independent single-photon sources, and the secret key rates are dependent on detecting two photons—one from each source. Here, we demonstrate a proof-of-principle experiment of a QKD scheme that removes the need for a two-photon system and instead uses the idea of a two-qubit single-photon to significantly simplify the implementation and improve the efficiency of mdiQKD in several aspects.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2020

Matter-wave interference of a native polypeptide

The de Broglie wave nature of matter is a paradigmatic example of quantum physics and it has been exploited in precision measurements of forces and fundamental constants. However, matter-wave interferometry has remained an outstanding challenge for natural polypeptides, building blocks of life, which are fragile and difficult to handle. Here, we demonstrate the wave nature of gramicidin, a natural antibiotic composed of 15 amino acids. Its center of mass is delocalized over more than 20 times the molecular size in our timedomain Talbot-Lau interferometer. We compare the observed interference fringes with a model that includes both a rigorous treatment of the peptide’s quantum wave nature as well as a quantum chemical assessment of its optical properties to distinguish our result from classical predictions. The realization of quantum optics with this prototypical biomolecule paves the way for quantum-assisted measurements on a large class of biologically relevant molecules.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2025

Non-local detection of coherent Yu–Shiba–Rusinov quantum projections

Probing spatially confined quantum states from afar—a long-sought goal to minimize external interference—has been proposed to be feasible in condensed-matter systems through the coherent projection of the state. This can be achieved by engineering the eigenstates of the electron sea that surrounds the quantum state using cages built atom by atom, the so-called quantum corrals. However, the demonstration of the coherent nature of the projection and manipulation of its quantum composition are still important goals. Here we show this for the coherent projection of a Yu–Shiba–Rusinov quantum state that is induced by a magnetic impurity, using the eigenmodes of corrals on the surface of a superconductor. This enables us to manipulate the particle–hole composition of the projected state by tuning the corral eigenmodes through the Fermi energy. Our results demonstrate a controlled non-local method for the detection of magnet–superconductor hybrid quantum states.

quantum mechanics↗
DOE OSTI2018

Generation of nonuniformly polarised vortex Bessel beams by an interference polariser

A new optical system is proposed for the generation of azimuthally and radially polarised vortex Bessel beams. The system is based on the transformation of conical wavefronts passing through an interference polarisation plate. The polarisation characteristics during the beam formation are controlled by changing the curvature of the wavefront of the beam illuminating a diffractive axicon. Radially and azimuthally polarised vortex Bessel beams are experimentally obtained using a binary phase axicon. (laser beams)

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2014

A compact, multichannel, and low noise arbitrary waveform generator

A new type of high functionality, fast, compact, and easy programmable arbitrary waveform generator for low noise physical measurements is presented. The generator provides 7 fast differential waveform channels with a maximum bandwidth up to 200 MHz frequency. There are 6 fast pulse generators on the generator board with 78 ps time resolution in both duration and delay, 3 of them with amplitude control. The arbitrary waveform generator is additionally equipped with two auxiliary slow 16 bit analog-to-digital converters and four 16 bit digital-to-analog converters for low frequency applications. Electromagnetic shields are introduced to the power supply, digital, and analog compartments and with a proper filter design perform more than 110 dB digital noise isolation to the output signals. All the output channels of the board have 50 Ω SubMiniature version A termination. The generator board is suitable for use as a part of a high sensitive physical equipment, e.g., fast read out and manipulation of nuclear magnetic resonance or superconducting quantum systems and any other application, which requires electromagnetic interference free fast pulse and arbitrary waveform generation.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2018

Pyrolysis of cyclopentanone: A shock tube and laser absorption study

The chemical kinetics of cyclopentanone, an attractive fuel for spark ignition engines, was studied in a double-diaphragm, heated shock tube at pressures near 10atm over the temperature range of 1173-1416K. A fuel concentration of 0.5% was chosen to investigate the pressure, emission, and carbon monoxide time-histories during cyclopentanone pyrolysis in argon. CO mole fractions were measured behind reflected shock waves with a continuous wave distributed feedback quantum cascade laser at 2183.22cm -1 , with no interference from other intermediates. Measured values were compared to two recent chemical kinetic mechanisms.

09 BIOMASS FUELS↗
DOE OSTI2015

Mapping the near-field propagation of surface plasmons on terahertz metasurfaces

Controlling the propagation of surface plasmon polaritons is essential in developing highly integrated photonic devices. By using near-field scanning terahertz microscopy, we experimentally demonstrate that polarization-controlled tunable surface plasmons (SPs) could be directionally excited on a metal surface with carved columns of aperture resonators under special arrangement. The experimental results reveal that terahertz SPs could be unidirectionally launched in opposite directions owning to destructive and constructive interferences on the two sides with circularly polarized incident waves of opposite handedness. Meanwhile, the linearly polarized wave is able to excite the terahertz SPs along either side of the structures. The presented results would be useful to implement functional terahertz plasmonic devices.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

Thermal radiation from optically driven Kerr (χ{sup (3)}) photonic cavities

We describe thermal radiation from nonlinear (χ{sup (3)}) photonic cavities coupled to external channels and subject to incident monochromatic light. Our work extends related work on nonlinear mechanical oscillators to the problem of thermal radiation, demonstrating that bistability can enhance thermal radiation by orders of magnitude and result in strong lineshape alternations, including “super-narrow spectral peaks” occurring at the onset of kinetic phase transitions. We show that when the cavities are designed to exhibit perfect linear emissivity (rate matching), such thermally activated transitions can be exploited to dramatically tune the output power and radiative properties of the cavity, leading to a kind of Kerr-mediated thermo-optic effect. Finally, we demonstrate that in certain parameter regimes, the output radiation exhibits Stokes and anti-Stokes side peaks whose relative magnitudes can be altered by tuning the internal temperature of the cavity relative to its surroundings, a consequence of strong correlations and interference between the emitted and reflected radiation.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2014

Cavity-photon-switched coherent transient transport in a double quantum waveguide

We study a cavity-photon-switched coherent electron transport in a symmetric double quantum waveguide. The waveguide system is weakly connected to two electron reservoirs, but strongly coupled to a single quantized photon cavity mode. A coupling window is placed between the waveguides to allow electron interference or inter-waveguide transport. The transient electron transport in the system is investigated using a quantum master equation. We present a cavity-photon tunable semiconductor quantum waveguide implementation of an inverter quantum gate, in which the output of the waveguide system may be selected via the selection of an appropriate photon number or “photon frequency” of the cavity. In addition, the importance of the photon polarization in the cavity, that is, either parallel or perpendicular to the direction of electron propagation in the waveguide system is demonstrated.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗