National Institute of Standards and Technology

Nurk S., Koren S., Rhie A., Rautiainen M., Bzikadze A.V., Mikheenko A., Vollger M.R., Altemose N., Uralsky L., Gershman A., Aganezov S., Hoyt S.J., Diekhans M., Logsdon G.A., Alonge M., et. al.

Since its initial release in 2000, the human reference genome has covered only the euchromatic fraction of the genome, leaving important heterochromatic regions unfinished. Addressing the remaining 8% of the genome, the Telomere-to-Telomere (T2T) Consortium presents a complete 3.055 billion–base pair sequence of a human genome, T2T-CHM13, that includes gapless assemblies for all chromosomes except Y, corrects errors in the prior references, and introduces nearly 200 million base pairs of sequence containing 1956 gene predictions, 99 of which are predicted to be protein coding. The completed regions include all centromeric satellite arrays, recent segmental duplications, and the short arms of all five acrocentric chromosomes, unlocking these complex regions of the genome to variational and functional studies.

García de Arquer F.P., Dinh C., Ozden A., Wicks J., McCallum C., Kirmani A.R., Nam D., Gabardo C., Seifitokaldani A., Wang X., Li Y.C., Li F., Edwards J., Richter L.J., Thorpe S.J., et. al.

Graceful choreography for CO 2 and H 2 O One challenge for efficient electrochemical reduction of carbon dioxide (CO 2 ) is that the gas is hydrophobic, but many of its desirable reactions require water (H 2 O). García de Arquer et al. addressed this problem by combining a copper electrocatalyst with an ionomer assembly that intersperses sulfonate-lined paths for the H 2 O with fluorocarbon channels for the CO 2 . The electrode architecture enables production of two-carbon products such as ethylene and ethanol at current densities just over an ampere per square centimeter. Science , this issue p. 661

Shastri B.J., Tait A.N., Ferreira de Lima T., Pernice W.H., Bhaskaran H., Wright C.D., Prucnal P.R.

Research in photonic computing has flourished due to the proliferation of optoelectronic components on photonic integration platforms. Photonic integrated circuits have enabled ultrafast artificial neural networks, providing a framework for a new class of information processing machines. Algorithms running on such hardware have the potential to address the growing demand for machine learning and artificial intelligence in areas such as medical diagnosis, telecommunications, and high-performance and scientific computing. In parallel, the development of neuromorphic electronics has highlighted challenges in that domain, particularly related to processor latency. Neuromorphic photonics offers sub-nanosecond latencies, providing a complementary opportunity to extend the domain of artificial intelligence. Here, we review recent advances in integrated photonic neuromorphic systems, discuss current and future challenges, and outline the advances in science and technology needed to meet those challenges. Photonics offers an attractive platform for implementing neuromorphic computing due to its low latency, multiplexing capabilities and integrated on-chip technology.

Lin R., Xiang S., Zhou W., Chen B.

Gas separation is a very important industrial process for manufacturing chemicals, fuels, plastics, and polymers but is also energy intensive through the traditional cryogenic distillations. Adsorptive gas separation by porous materials can potentially fulfill the energy-efficient separation economy. Metal-organic frameworks (MOFs), a new generation of porous materials, have been demonstrated for their promise in addressing important gas separations. In this review, we outline the uniqueness and basic design principles of MOF chemistry for gas separation in terms of their specific pore chemistry and molecular recognition. The finely tuned micropores for the high sieving effects and immobilized functional sites on pore surfaces for specific recognition of gas molecules have enabled us to develop a variety of microporous MOFs for many gas separations with both high separation selectivity and productivity. We highlight the major progress and achievements in this very important topic, which will further facilitate the extensive research endeavors and promote their industrial implementation for gas separation.

Grollier J., Querlioz D., Camsari K.Y., Everschor-Sitte K., Fukami S., Stiles M.D.

Neuromorphic computing uses brain-inspired principles to design circuits that can perform computational tasks with superior power efficiency to conventional computers. Approaches that use traditional electronic devices to create artificial neurons and synapses are, however, currently limited by the energy and area requirements of these components. Spintronic nanodevices, which exploit both the magnetic and electrical properties of electrons, can increase the energy efficiency and decrease the area of these circuits, and magnetic tunnel junctions are of particular interest as neuromorphic computing elements because they are compatible with standard integrated circuits and can support multiple functionalities. Here, we review the development of spintronic devices for neuromorphic computing. We examine how magnetic tunnel junctions can serve as synapses and neurons, and how magnetic textures, such as domain walls and skyrmions, can function as neurons. We also explore spintronics-based implementations of neuromorphic computing tasks, such as pattern recognition in an associative memory, and discuss the challenges that exist in scaling up these systems. This Review Article examines the development of spintronic devices for neuromorphic computing, exploring how magnetic tunnel junctions and magnetic textures can act as artificial neurons and synapses, as well as considering the challenges that exist in scaling up current systems.

Hirscher M., Yartys V.A., Baricco M., Bellosta von Colbe J., Blanchard D., Bowman R.C., Broom D.P., Buckley C.E., Chang F., Chen P., Cho Y.W., Crivello J., Cuevas F., David W.I., de Jongh P.E., et. al.

Magnesium hydride owns the largest share of publications on solid materials for hydrogen storage. The Magnesium group of international experts contributing to IEA Task 32 Hydrogen Based Energy Storage recently published two review papers presenting the activities of the group focused on magnesium hydride based materials and on Mg based compounds for hydrogen and energy storage. This review article not only overviews the latest activities on both fundamental aspects of Mg-based hydrides and their applications, but also presents a historic overview on the topic and outlines projected future developments. Particular attention is paid to the theoretical and experimental studies of Mg-H system at extreme pressures, kinetics and thermodynamics of the systems based on MgH2,nanostructuring, new Mg-based compounds and novel composites, and catalysis in the Mg based H storage systems. Finally, thermal energy storage and upscaled H storage systems accommodating MgH2 are presented.

Fortier T., Baumann E.

Optical frequency combs were developed nearly two decades ago to support the world’s most precise atomic clocks. Acting as precision optical synthesizers, frequency combs enable the precise transfer of phase and frequency information from a high-stability reference to hundreds of thousands of tones in the optical domain. This versatility, coupled with near-continuous spectroscopic coverage from microwave frequencies to the extreme ultra-violet, has enabled precision measurement capabilities in both fundamental and applied contexts. This review takes a tutorial approach to illustrate how 20 years of source development and technology has facilitated the journey of optical frequency combs from the lab into the field. Optical frequency combs were realized nearly two decades ago to support the development of the world’s most precise atomic clocks, but their versatility has since made them useful instruments well beyond their original goal, and spans across a wide variety of fundamental and applied physics in a wide range of wavelengths. Fortier and Baumann present a comprehensive review of developments in optical frequency comb technology and a view to the future with these technologies.

Chen Z., Li P., Anderson R., Wang X., Zhang X., Robison L., Redfern L.R., Moribe S., Islamoglu T., Gómez-Gualdrón D.A., Yildirim T., Stoddart J.F., Farha O.K.

Delivering methane and hydrogen The pressure for onboard storage of methane and hydrogen on vehicles is usually limited to 100 bar for the use of lightweight containers, but the amount stored can be increased with the use of absorbent materials. Efficient storage and delivery require a balance of volumetric and gravimetric storage. Chen et al. designed a metal-organic framework with trialuminum nodes and a large hexadentate aromatic linker that optimizes both parameters. This material surpassed the U.S. Department of Energy targets for methane and had a deliverable capacity of 14% by weight for hydrogen. Science , this issue p. 297

Madsen L.S., Laudenbach F., Askarani M.F., Rortais F., Vincent T., Bulmer J.F., Miatto F.M., Neuhaus L., Helt L.G., Collins M.J., Lita A.E., Gerrits T., Nam S.W., Vaidya V.D., Menotti M., et. al.

A quantum computer attains computational advantage when outperforming the best classical computers running the best-known algorithms on well-defined tasks. No photonic machine offering programmability over all its quantum gates has demonstrated quantum computational advantage: previous machines1,2 were largely restricted to static gate sequences. Earlier photonic demonstrations were also vulnerable to spoofing3, in which classical heuristics produce samples, without direct simulation, lying closer to the ideal distribution than do samples from the quantum hardware. Here we report quantum computational advantage using Borealis, a photonic processor offering dynamic programmability on all gates implemented. We carry out Gaussian boson sampling4 (GBS) on 216 squeezed modes entangled with three-dimensional connectivity5, using a time-multiplexed and photon-number-resolving architecture. On average, it would take more than 9,000 years for the best available algorithms and supercomputers to produce, using exact methods, a single sample from the programmed distribution, whereas Borealis requires only 36 μs. This runtime advantage is over 50 million times as extreme as that reported from earlier photonic machines. Ours constitutes a very large GBS experiment, registering events with up to 219 photons and a mean photon number of 125. This work is a critical milestone on the path to a practical quantum computer, validating key technological features of photonics as a platform for this goal. Gaussian boson sampling is performed on 216 squeezed modes entangled with three-dimensional connectivity5, using Borealis, registering events with up to 219 photons and a mean photon number of 125.

Elshaari A.W., Pernice W., Srinivasan K., Benson O., Zwiller V.

Recent developments in chip-based photonic quantum circuits have radically impacted quantum information processing. However, it is challenging for monolithic photonic platforms to meet the stringent demands of most quantum applications. Hybrid platforms combining different photonic technologies in a single functional unit have great potential to overcome the limitations of monolithic photonic circuits. Our Review summarizes the progress of hybrid quantum photonics integration, discusses important design considerations, including optical connectivity and operation conditions, and highlights several successful realizations of key physical resources for building a quantum teleporter. We conclude by discussing the roadmap for realizing future advanced large-scale hybrid devices, beyond the solid-state platform, which hold great potential for quantum information applications. The Review summarizes the progress of hybrid quantum photonics integration in terms of its important design considerations and fabrication approaches, and highlights some successful realizations of key physical resources for building integrated quantum devices, such as quantum teleporters, quantum repeaters and quantum simulators.