Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “quantum state engineering”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 361 records · Page 20
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Quantum Anomalies in Condensed Matter

Quantum materials provide a fertile ground in which to test and realize unusual phenomena such as quantum anomalies predicted by quantum field theory. There are three important symmetries that are broken when classical field theory is moved into the quantum regime, the scale anomaly, the axial (chiral) anomaly, and the parity anomaly. Several potential device applications may be realized by the discovery of quantum anomalies in condensed matter, enabled by the new physics they embody, including ultra‐sensitive dark matter detectors, far infrared optical modulators, micro‐bolometric detectors, low‐dissipation ballistic transporters, terahertz‐based qubits, terahertz polarization state controls, passive magnetic field sensors, stable topological superconductors that host Majorana fermions, and qubits topologically protected against decoherence. In this perspective article, the definition of these quantum anomalies is laid out, how little is known in the context of condensed matter, and how quantum anomalies are predicted to manifest as anomalous electronic, thermal, and magnetic behavior in experiments on topological quantum materials, including Weyl and Dirac semimetals. Furthermore, the importance that mechanical strain and defects will play in modifying signatures of quantum anomalies is discussed.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Telecom-Wavelength Single-Photon Emitters in Multilayer InSe

The development of robust and efficient single-photon emitters (SPEs) at telecom wavelengths is critical for advancements in quantum information science. Two-dimensional (2D) materials have recently emerged as promising sources for SPEs, owing to their high photon extraction efficiency, facile coupling to external fields, and seamless integration into photonic circuits. In this study, we demonstrate the creation of SPEs emitting in the 1000–1550 nm near-infrared range by coupling 2D indium selenide (InSe) with strain-inducing nanopillar arrays. The emission wavelength exhibits a strong dependence on the number of layers. Hanbury Brown and Twiss experiments conducted at 10 K reveal clear photon antibunching, confirming the single-photon nature of the emissions. In conclusion, density-functional-theory calculations and scanning-tunneling-microscopy analyses provide insights into the electronic structures and defect states, elucidating the origins of the SPEs.

2D Material↗
DOE OSTI2021

Oxidation and pyrolysis of methyl propyl ether

The ignition, oxidation, and pyrolysis chemistry of methyl propyl ether (MPE) was probed experimentally at several different conditions, and a comprehensive chemical kinetic model was constructed to help understand the observations, with many of the key parameters computed using quantum chemistry and transition state theory. Experiments were carried out in a shock tube measuring time variation of CO concentrations, in a flow tube measuring product concentrations, and in a rapid compression machine (RCM) measuring ignition delay times. The detailed reaction mechanism was constructed using the Reaction Mechanism Generator software. Sensitivity and flux analyses were used to identify key rate and thermochemical parameters, which were then computed using quantum chemistry to improve the mechanism. Validation of the final model against the 1-20 bar 600-1500 K experimental data is presented with a discussion of the kinetics. The model is in excellent agreement with most of the shock tube and RCM data. Strong non-monotonic variation in conversion and product distribution is observed in the flow-tube experiments as the temperature is increased, and unusually strong pressure dependence and significant heat release during the compression stroke is observed in the RCM experiments. These observations are largely explained by a close competition between radical decomposition and addition to O2 at different sites in MPE; this causes small shifts in conditions to lead to big shifts in the dominant reaction pathways. The validated mechanism was used to study the chemistry occurring during ignition in a diesel engine, simulated using Ignition Quality Test (IQT) conditions. At the IQT conditions, where the MPE concentration is higher, bimolecular reactions of peroxy radicals are much more important than in the RCM.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Thermalization at low temperatures via weakly damped multisite baths

We study the thermalization properties of one-dimensional open quantum systems coupled to baths at their boundary. The baths are driven to their thermal states via Lindblad operators, while the system undergoes Hamiltonian dynamics. We specifically consider multisite baths and investigate the extent to which the late-time steady state resembles a Gibbs state at some controllable temperature set by the baths. We study three models: a noninteracting fermion model accessible via free-fermion technology, and two interacting models, the XZ model and the chiral clock model, which are accessible via tensor network methods. We show that, by tuning towards the weak coupling and slow relaxation limits, one can engineer low temperatures in the bulk of the system provided the bath size is big enough. Here, we use this capability to study energy transport in the XZ model at lower temperatures than previously reported. Our work paves the way for future studies of interacting open quantum systems at low temperatures.

1-dimensional spin chains↗
DOE OSTI2020

All-Epitaxial Integration of Long-Wavelength Infrared Plasmonic Materials and Detectors for Enhanced Responsivity

Here, infrared detectors using monolithically integrated doped semiconductor “designer metals” are proposed and experimentally demonstrated. We leverage the “designer metal” groundplanes to form resonant cavities with enhanced absorption tuned across the long-wave infrared (LWIR). Detectors are designed with two target absorption enhancement wavelengths: 8 and 10 μm. The core of our detectors are quantum-engineered LWIR type-II superlattice p-i-n detectors with total thicknesses of only 1.42 and 1.80 μm for the 8 and 10 μm absorption enhancement devices, respectively. Our 8 and 10 μm structures show peak external quantum efficiencies of 45 and 27%, which are 4.5× and 2.7× enhanced, respectively, compared to control structures. We demonstrate the clear advantages of this detector architecture, both in terms of ease of growth/fabrication and enhanced device performance. The proposed architecture is absorber- and device-structure agnostic, much thinner than state-of-the-art LWIR T2SLs, and offers the opportunity for the integration of low dark current LWIR detector architectures for significant enhancement of IR detectivity.

42 ENGINEERING↗
DOE OSTI2023

Quantum Composites with Charge-Density-Wave Fillers

Here, a unique class of advanced materials—quantum composites based on polymers with fillers composed of a van der Waals quantum material that reveals multiple charge-density-wave quantum condensate phases—is demonstrated. Materials that exhibit quantum phenomena are typically crystalline, pure, and have few defects because disorder destroys the coherence of the electrons and phonons, leading to collapse of the quantum states. The macroscopic charge-density-wave phases of filler particles after multiple composite processing steps are successfully preserved in this work. The prepared composites display strong charge-density-wave phenomena even above room temperature. The dielectric constant experiences more than two orders of magnitude enhancement while the material maintains its electrically insulating properties, opening a venue for advanced applications in energy storage and electronics. The results present a conceptually different approach for engineering the properties of materials, extending the application domain for van der Waals materials.

36 MATERIALS SCIENCE↗
DOE OSTI2025

Quantum Software Engineering (Dagstuhl Seminar 24512)

The Dagstuhl Seminar 24512 on "Quantum Software Engineering" was held from December 15 to 20, 2024. It brought together 26 participants from industry and academia from 13 different countries, including senior and junior researchers as well as practitioners in the field of Quantum Software Engineering. The aim of the seminar was to advance software engineering methods and tools for the engineering of hybrid quantum systems by promoting personal interaction and open discussion among researchers who are already working in this emerging area of knowledge. The first day of the seminar was devoted to the topic "When software engineering meets quantum mechanics", while the second day focused on "Quantum software engineering and its challenges." During both days, 16 invited presentations were given. The rest of the seminar was organized into three working groups to address the topics "Quantum Software Design, Modelling and Architecturing", "Adaptive Hybrid Quantum Systems", and "Quantum Software Quality Assurance". The seminar was a very fruitful experience for all participants both in terms of scientific outcomes and in terms of the personal relationships that were generated to jointly address future experiences.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2025

Solitons in Arbitrary Dimensions Stabilized by Photon-Mediated Interactions

We propose a scheme to generate solitons in arbitrary dimensions, in a matter-wave interferometer, without the need of quantum degeneracy. In our setting, solitons emerge by balancing the single-particle dispersion with engineered cavity-mediated exchange interactions between two wave packets, which, at the appropriate conditions, remain bound to each other and dispersion-free. For detection in thermal gases, we propose an interferometric probing scheme instead of traditional time-of-flight imaging.

cavity quantum electrodynamics↗
DOE OSTI2020

Mott and generalized Wigner crystal states in WSe 2 /WS 2 moiré superlattices

Moiré superlattices can be used to engineer strongly correlated electronic states in two-dimensional van der Waals heterostructures, as recently demonstrated in the correlated insulating and superconducting states observed in magic-angle twisted-bilayer graphene and ABC trilayer graphene/boron nitride moiré superlattices. Transition metal dichalcogenide moiré heterostructures provide another model system for the study of correlated quantum phenomena because of their strong light–matter interactions and large spin–orbit coupling. However, experimental observation of correlated insulating states in this system is challenging with traditional transport techniques. Here we report the optical detection of strongly correlated phases in semiconducting WSe 2 /WS 2 moiré superlattices. We use a sensitive optical detection technique and reveal a Mott insulator state at one hole per superlattice site and surprising insulating phases at 1/3 and 2/3 filling of the superlattice, which we assign to generalized Wigner crystallization on the underlying lattice. Furthermore, the spin–valley optical selection rules of transition metal dichalcogenide heterostructures allow us to optically create and investigate low-energy excited spin states in the Mott insulator. We measure a very long spin relaxation lifetime of many microseconds in the Mott insulating state, orders of magnitude longer than that of charge excitations. Here, our studies highlight the value of using moiré superlattices beyond graphene to explore correlated physics.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Enhancing quantum clocks and sensors with randomization and decoherence

This letter shows how incoherent dynamics can lead to metrological advantages in quantum sensing. The results rely on the fact that incoherent dynamics lead to an additive contribution to the quantum Fisher information about time. Such an additive contribution can reduce the error of optimal estimation protocols, as implied by the quantum Cramér–Rao bound. I characterize regimes in which the estimation of a time interval or a frequency is enhanced by decoherence, thereby identifying cases in which incoherent dynamics serve as a metrological resource. The decoherence processes that yield enhanced precision of quantum sensors can be engineered by randomized Hamiltonian dynamics. I illustrate the results with protocols that display improved sensing of time intervals or global fields by qubit and photonic sensors. Enhanced precision of time intervals is achieved with Hamiltonians that include randomized global parameters. Enhanced precision in field estimation is obtained by randomized sensing times.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2026

Design Rules for Open-Shell Molecular Wires: Insights from Correlated Many-Body Transport

Open-shell π-conjugated systems have emerged as promising molecular wires that can sustain unusually high low-bias conductance over tens of nanometers. However, predictive design rules remain limited because near-degeneracy and spin polarization give rise to correlated electronic states that are not reliably captured by standard density functional theory and Landauer transport descriptions. Here, we establish physically transparent design rules for long-range, weakly length-dependent charge transport based on the interplay between bond-length alternation and electron–electron interactions. Using a fully correlated transport framework that combines density matrix renormalization group calculations with nonequilibrium Green’s function embedding, we show that weak dimerization maintains spatially extended edge states, while moderate on-site interaction stabilizes open-shell character without excessively separating transport-relevant resonances. This balance yields zero-bias transmission that is largely insensitive to molecular length, providing a route to connect chemically tunable structure to correlated transport beyond mean-field descriptions.

Charge transport↗
DOE OSTI2022

Electronic landscape of the f -electron intermetallics with the ThCr 2 Si 2 structure

Although strongly correlated f -electron systems are well known as reservoirs for quantum phenomena, a persistent challenge is to design specific states. What is often missing are simple ways to determine whether a given compound can be expected to exhibit certain behaviors and what tuning vector(s) would be useful to select the ground state. In this review, we address this question by aggregating information about Ce, Eu, Yb, and U compounds with the ThCr 2 Si 2 structure. We construct electronic/magnetic state maps that are parameterized in terms of unit cell volumes and d -shell filling, which reveals useful trends including that (i) the magnetic and nonmagnetic examples are well separated, and (ii) the crossover regions harbor the examples with exotic states. These insights are used to propose structural/chemical regions of interest in these and related materials, with the goal of accelerating discovery of the next generation of f -electron quantum materials.

42 ENGINEERING↗
DOE OSTI2026

Emulating 2D Materials with Magnons

Spin waves (magnons) in two-dimensional (2D) materials have received increasing interest due to their unique states and potential for tunability. However, many interesting features of these systems, including Dirac points and topological states, occur at high frequencies, where experimental probes are limited. Here, we study a crystal formed by patterning a hexagonal array of holes in a perpendicularly magnetized thin film. Through simulation, we find that the magnonic band structure imitates that of graphene, but additionally has some kagomelike character and includes a few flat bands. Surprisingly, its nature can be understood using a nine-band tight-binding Hamiltonian. This clear analogy to 2D materials enables band-gap engineering in 2D, topological magnons along 1D phase boundaries, and spectrally isolated modes at 0D point defects. Interestingly, the 1D phase boundaries allow access to the valley degree of freedom through a magnonic analog of the quantum valley Hall insulator. These approaches can be extended to other magnonic systems, but are potentially more general due to the simplicity of the model, which resembles existing results from electron, phonon, photon, and cold-atom systems. This finding brings the physics of spin waves in 2D materials to more experimentally accessible scales, augments it, and outlines a few principles for controlling magnonic states.

Ferrimagnets↗
DOE OSTI2020

Supported and coordinated single metal site electrocatalysts

The ever-increasing global environmental and energy crisis issues necessitates technological innovation, especially in the development of renewable energy-related devices, such as electrochemical energy conversion and storage technologies, including fuel cells, water electrolyzers, and CO 2 electrolyzers. Reliable and sustainable energy conversion devices are highly dependent on engineering of electrocatalysts. Furthermore, state-of-the-art electrocatalysts for these electrochemical conversion systems are usually platinum group metal (PGM)-based nanoparticles with high cost, which has sparked intensive research on atomically dispersed single metal site electrocatalysts for decreasing metal loadings and boosting catalytic efficiencies by taking advantage of their inherent electronic effects, quantum size effects, and metal-support interactions. In this review, we first introduced the intrinsic active site identification and stabilization, followed by addressing the mutual metal-support interactions, and most important, their correlations with catalytic properties. Next, the advances in synthetic strategies and characterization techniques for single metal site electrocatalysts are highlighted. Additionally, recent advances in single metal site electrocatalysts designs for applications in electrochemical conversion reactions are also presented. Finally, remaining challenges and a forward-looking perspective on this field of research are provided.

25 ENERGY STORAGE↗
DOE OSTI2021

Qubit spin ice

Artificial spin ices are frustrated spin systems that can be engineered, in which fine tuning of geometry and topology has allowed the design and characterization of exotic emergent phenomena at the constituent level. Here, we report a realization of spin ice in a lattice of superconducting qubits. Unlike conventional artificial spin ice, our system is disordered by both quantum and thermal fluctuations. The ground state is classically described by the ice rule, and we achieved control over a fragile degeneracy point, leading to a Coulomb phase. The ability to pin individual spins allows us to demonstrate Gauss’s law for emergent effective monopoles in two dimensions. The demonstrated qubit control lays the groundwork for potential future study of topologically protected artificial quantum spin liquids.

36 MATERIALS SCIENCE↗
DOE OSTI2022

Spectrally separable photon-pair generation in dispersion engineered thin-film lithium niobate

Existing nonlinear-optic implementations of pure, unfiltered heralded single-photon sources do not offer the scalability required for densely integrated quantum networks. Additionally, lithium niobate has hitherto been unsuitable for such use due to its material dispersion. We engineer the dispersion and the quasi-phasematching conditions of a waveguide in the rapidly emerging thin-film lithium niobate platform to generate spectrally separable photon pairs in the telecommunications band. Such photon pairs can be used as spectrally pure heralded single-photon sources in quantum networks. We estimate a heralded-state spectral purity of >94% based on joint spectral intensity measurements. Further, a joint spectral phase-sensitive measurement of the unheralded time-integrated second-order correlation function yields a heralded-state purity of (86 ± 5)%.

36 MATERIALS SCIENCE↗
DOE OSTI2021

Nanotesla Magnetometry with the Silicon Vacancy in Silicon Carbide

Silicon carbide is a promising host material for spin-defect-based quantum sensors owing to its commercial availability and established techniques for electrical and optical microfabricated device integration. The negatively charged silicon vacancy is one of the leading spin defects studied in silicon carbide owing to its near-telecom photoemission, high spin number, and nearly temperature-independent ground-state zero-field splitting. We report the realization of nanotesla shot-noise-limited ensemble magnetometry based on optically detected magnetic resonance with the silicon vacancy in 4H silicon carbide. By coarsely optimizing the anneal parameters and minimizing power broadening, we achieve a sensitivity of 50 nT/√Hz and a theoretical shot-noise-limited sensitivity of 3.5 nT/√Hz. This is accomplished without utilizing complex photonic engineering, control protocols, or applying excitation powers greater than a watt. This work demonstrates that the silicon vacancy in silicon carbide provides a low-cost and simple approach to quantum sensing of magnetic fields.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2020

Hot-pressed ceramic Fe:ZnSe gain-switched laser

We report the first room temperature gain-switched Fe:ZnSe hot-pressed ceramic laser pumped by 2.94 µm radiation of mechanically Q-switched Er:YAG laser. The maximum output energy at 4.2 µm was 41 mJ at 3 Hz repetition rate and 120 ns pulse duration. The measured slope efficiency was 25% with respect to the absorbed energy. This technique could be attractive for the future development of high-energy short-pulse solid-state mid-IR systems.

36 MATERIALS SCIENCE↗