Gate-Defined Quantum Dots in Ge/SiGe Quantum Wells as a Platform for Spin Qubits

In the field of semiconductor quantum dot spin qubits, there is growing interest in leveraging the unique properties of hole-carrier systems and their intrinsically strong spin-orbit coupling to engineer novel qubits. Recent advances in semiconductor heterostructure growth have made available high quality, undoped Ge/SiGe quantum wells, consisting of a pure strained Ge layer flanked by Ge-rich SiGe layers above and below. These quantum wells feature heavy hole carriers and a cubic Rashba-type spin-orbit interaction. Here, we describe progress toward realizing spin qubits in this platform, including development of multi-metal-layer gated device architectures, device tuning protocols, and charge-sensing capabilities. Iterative improvement of a three-layer metal gate architecture has significantly enhanced device performance over that achieved using an earlier single-layer gate design. We discuss ongoing, simulation-informed work to fine-tune the device geometry, as well as efforts toward a single-spin qubit demonstration.

At the close of each fiscal year, the US Department of Energy (DOE) Sustainability Performance Office (SPO) issues guidance documents and technical resource aids/tools necessary for DOE sites and national laboratories to complete sustainability reporting requirements. SPO is part of the DOE Office of Asset Management. As required by DOE Order 436.1A, Departmental Sustainability, each site develops and commits to an annual site sustainability plan (SSP) that identifies its respective contribution toward meeting DOE’s sustainability goals. SPO collects and compiles information reported by each site to develop an agency-wide sustainability report and implementation plan, which is used to report DOE sustainability progress to the federal government as required by all major federal agencies. DOE launched a formal Sustainability Office and annual SSP process in 2011. Each year, Oak Ridge National Laboratory (ORNL), in concert with the DOE Office of Science (SC), provides the resources essential to fulfill its commitment to deliver a complete and accurate SSP and quality performance data for entry into the DOE Sustainability Dashboard managed by SPO. The performance data entered by each DOE site are then combined to disclose the progress of each DOE program office and are further combined to show comprehensive progress for the agency. The Office of Asset Management assists program offices in sustaining their missions, freeing up resources by reducing waste, avoiding excess expenditure on utilities, maximizing productivity, and improving the efficiency of facilities and processes. By focusing on mission needs, programs and associated DOE sites can help the agency meet its sustainability goals as outlined in federal statutory and regulatory requirements. In FY 2022, the SSP Guidance/Instructions (US Department of Energy, Sustainability Performance Office) was updated to capture requirements from Executive Order (EO) 14008, Tackling the Climate Crisis at Home and Abroad; the Energy Act of 2020 (EAct 20); actions outlined in DOE’s Climate Adaptation and Resilience Plan and Sustainability Plan; and EO 14057, Catalyzing Clean Energy Industries and Jobs Through Federal Sustainability. Updates in SSP guidance help to minimize and streamline reporting while simultaneously addressing updated federal requirements. Per DOE, each SSP should provide an overview of the site’s planned actions and of efforts and accomplishments during the reporting period. SPO collects and compiles information reported by each site to develop DOE’s Annual Sustainability Report, Climate Adaptation and Resilience Plan, and Annual Energy Management Report to Congress. The agency goal has been to lower the reporting burden for sites and increase and improve the consistency of information available to decision-makers, allowing them to better identify projects and potential for increased efficiency and to reduce waste, lower emissions, and enhance operational resilience. Sites may elect to produce more polished publications for their leadership and stakeholders, but this step is no longer required. The ORNL SSP narrative report (this document) and the reporting of DOE SPO Sustainability Dashboard performance data is a collaborative effort of approximately 30 subject matter experts (SMEs) from ORNL facility management, mission support, and research divisions. Annually, these associates come together to provide a report that can be used by DOE to demonstrate continued agency progress in energy efficiency and sustainable federal operations.

DOE complies with all Federal regulations governing radioactive material shipments to maintain an excellent safety record. The US Department of Energy (DOE) uses radioactive material for National defense and research and development activities and is a major shipper of this material. DOE shipments go through almost all 50 states in both government and commercial vehicles via air, highway, rail, and water. DOE manages the transportation of the following: uranium ore from mines to processing facilities where the uranium is enriched and prepared as reactor fuel; reactor fuel to nuclear reactors; materials for research in new energy technologies; special nuclear materials for defense purposes; reactor byproducts to research laboratories, industrial plants, and medical institutions; and radioactive waste to interim storage and disposal sites. As with many substances, potential hazards arise in transporting radioactive material, and DOE takes stringent precautions to minimize and eliminate risk. DOE packages and transports according to the Department of Transportation's (DOT) Title 49 Code of Federal Regulations, Part 173 (49 CFR 173). In addition, DOE has adopted the packaging standards of the Nuclear Regulatory Commission (NRC). These regulations and standards are implemented through DOE safety and operational directives called DOE Orders. The safety record for shipping radioactive material clearly shows that the protection of the public and the environment is of the highest priority. Strict enforcement of regulations and ongoing research show DOE's commitment to maintain this excellent record. 21 figs.

Supercritical water oxidation (SCWO) is an emerging technology for industrial waste treatment and is being developed for treatment of the US Department of Energy (DOE) mixed hazardous and radioactive wastes. In the SCWO process, wastes containing organic material are oxidized in the presence of water at conditions of temperature and pressure above the critical point of water, 374 C and 22.1 MPa. DOE mixed wastes consist of a broad spectrum of liquids, sludges, and solids containing a wide variety of organic components plus inorganic components including radionuclides. This report is a review and evaluation of tubular reactor designs for supercritical water oxidation of US Department of Energy mixed waste. Tubular reactors are evaluated against requirements for treatment of US Department of Energy mixed waste. Requirements that play major roles in the evaluation include achieving acceptable corrosion, deposition, and heat removal rates. A general evaluation is made of tubular reactors and specific reactors are discussed. Based on the evaluations, recommendations are made regarding continued development of supercritical water oxidation reactors for US Department of Energy mixed waste.

This document provides information about the many reports and other materials made available by the US Department of Energy`s (DOE`s) Global Change Research Program (GCRP). It is divided into nine sections plus author and title indexes: Section A -- US Department of Energy Global Change Research Program research plans and summaries; Section B -- US Department of Energy Global Change Research Program technical reports; Section C -- US Department of energy Atmospheric Radiation Measurement (ARM) program reports; Section D -- Other US Department of Energy reports; Section E -- CDIAC reports; Section F -- CDIAC numeric data and computer model distribution; Section G -- other data sets distributed by CDIAC; Section H -- USDA reports on response of vegetation to carbon dioxide; Section I -- other publications.

Clark, Janecky, and Lane reply: The letters from William Alschuler and Anne Fenerty raise many interesting points; we will address the major ones. Of particular relevance is the unprecedented stakeholder involvement that enabled the cleanup of Rocky Flats. Although there were many perspectives surrounding issues such as cleanup levels, dirty demolition, landfill capping, and 903 Pad remediation, all organizations helped advance the removal of plutonium and reduction of the risks to metropolitan Denver.An example of stakeholder involvement and communications was the formulation of actinide cleanup levels. Many stakeholders were concerned by the original radionuclide soil action level (RSAL) of 651 picocuries per gram of plutonium, acceptable under Superfund regulations. Intense community concern prompted the Department of Energy (DOE) to fund a citizens’ group to reexamine RSALs; though members did not reach consensus, they helped emphasize protection of surface water that could leave the site during the necessary trade-off between cleanup of more highly contaminated surface soils and the disturbance of vegetation, streams, and soils. That extensive public process developed a much reduced RSAL for surface soil (50 pCi/g) while allowing for more residual contamination at depth beneath old building sites—an approach that had wide support. As Fenerty’s letter implies, not every stakeholder concern could be satisfied. The containerized waste was sent to two disposal facilities, one DOE’s and one commercial.Most of the site (3900 of 6200 acres) has been transferred to the Interior Department to become a national wildlife refuge. The former industrial area will remain restricted and under DOE jurisdiction. The cleanup has significantly reduced risk, but ongoing monitoring and maintenance by the DOE Office of Legacy Management remain vital to ensuring long-term protection of human health and the environment. In addition, the US Congress approved legislation in 2004 creating the Rocky Flats Stewardship Council to focus on issues central to the site’s post-closure care and management.Regarding independence, anyone in the US who has experience and expertise with plutonium has been funded at some time by DOE, including us and the Rocky Flats Citizens Advisory Board. As scientists, we always hope that our science is brought out in public discussions and then used to improve the technical basis for decision making, so that decisions will be more transparent, repeatable, and thus scientifically defensible. Describing the value, process, and results of our participation was a major driver in developing the article for Physics Today. For us, the invitation to become involved in cleaning up Rocky Flats was an ultimate opportunity for science in the public interest. We remain committed to working with all participants—site contractors, regulators, governments, stakeholder organizations, individuals, and the international scientific community.Rocky Flats, the largest, most complex environmental cleanup in US history, was completed nearly 50 years sooner and $30 billion lower than initial estimates. The cleanup removed plutonium and reduced risks to metropolitan Denver. It was many things, but through broad-ranging community participation, it is certainly not a cover-up.ADDITIONAL RESOURCESSection:ChooseTop of pageADDITIONAL RESOURCES <<CITING ARTICLES1. US Department of Energy, Office of Legacy Management, http://www.lm.doe.gov. Google Scholar2. US DOE, Office of Legacy Management, Rocky Flats site, http://www.lm.doe.gov/land/sites/co/rocky_flats/rocky.html. Google Scholar3. Rocky Flats Stewardship Council, http://www.rockyflatssc.org/index.html. Google Scholar4. National Research Council, Commission on Geosciences, Environment, and Resources, Long-Term Institutional Management of US Department of Energy Legacy Waste Sites (2000), National Academy Press, Washington, DC (2000), http://books.nap.edu/openbook.php?record_id=9949=R1. Google Scholar© 2007 American Institute of Physics.

The Atomic Energy Act, as amended, authorizes the United States (U.S.) Department of Energy (DOE) and its predecessor agencies to distribute nuclear materials to public or private institutions for the purposes of education as well as research and development. Significant transformations throughout the nuclear industry have led to changes in programmatic responsibility for loaned nuclear materials. DOE has established several programs to catalog, transfer ownership, retrieve, and/or dispose of these loaned nuclear materials. The variety of loaned nuclear material types as well as operational and regulatory variations between facility licensees have created unique challenges for the retrieval and dispositioning processes. These include packaging and transportation, confirmation of regulatory jurisdiction, property transfer, and disposal of sources with no remaining economic value. This paper explores the methods and actions taken by DOE to address these challenges. Lessons learned and the best practices identified from these programs are also presented.

There has been a need for a faster and cheaper deployment model for information technology (IT) solutions to address waste management needs at US Department of Energy (DOE) complex sites for years. Budget constraints, challenges in deploying new technologies, frequent travel, and increased job demands for existing employees have prevented IT organizations from staying abreast of new technologies or deploying them quickly. Despite such challenges, IT organizations have added significant value to waste management handling through better worker safety, tracking, characterization, and disposition at DOE complex sites. Systems developed for site-specific missions have broad applicability to waste management challenges and in many cases have been expanded to meet other waste missions. Radio frequency identification (RFID) and global positioning satellite (GPS)-enabled solutions have reduced the risk of radiation exposure and safety risks. New web-based and mobile applications have enabled precision characterization and control of nuclear materials. These solutions have also improved operational efficiencies and shortened schedules, reduced cost, and improved regulatory compliance. Collaboration between US Department of Energy (DOE) complex sites is improving time to delivery and cost efficiencies for waste management missions with new information technologies (IT) such as wireless computing, global positioning satellite (GPS), and radio frequency identification (RFID). Integrated solutions developed at separate DOE complex sites by new technology Centers of Excellence (CoE) have increased material control and accountability, worker safety, and environmental sustainability. CoEs offer other DOE sister sites significant cost and time savings by leveraging their technology expertise in project scoping, implementation, and ongoing operations.

The Radiation Emergency Assistance Center/Training Site (REAC/TS) is one of the US Department of Energy (DOE)/National Nuclear Security Administration (NNSA) Nuclear Emergency Response Team (NEST) assets and has been responding to radiological incidents since 1976. REAC/TS is in the Oak Ridge Institute for Science and Education (ORISE). A critical part of the REAC/TS mission is to provide emergency response, advice, and consultation on injuries and illnesses caused from ionizing radiation. Fortunately, radiation injuries are not frequent, but when they occur, they are more likely to be cutaneous radiation injuries (CRI) or internal contamination. In this paper, we will review selected cases from the REAC/TS experience in order to illustrate cutaneous patterns of injury and treatment options.

Waste minimization and pollution prevention are inherent goals within the operating procedures of Los Alamos National Security, LLC (LANS). The US Department of Energy (DOE) and LANS are required to submit an annual hazardous waste minimization report to the New Mexico Environment Department (NMED) in accordance with the Los Alamos National Laboratory (LANL or the Laboratory) Hazardous Waste Facility Permit. The report was prepared pursuant to the requirements of Section 2.9 of the LANL Hazardous Waste Facility Permit. This report describes the hazardous waste minimization program (a component of the overall Waste Minimization/Pollution Prevention [WMin/PP] Program) administered by the Environmental Stewardship Group (ENV-ES). This report also supports the waste minimization and pollution prevention goals of the Environmental Programs Directorate (EP) organizations that are responsible for implementing remediation activities and describes its programs to incorporate waste reduction practices into remediation activities and procedures. LANS was very successful in fiscal year (FY) 2013 (October 1-September 30) in WMin/PP efforts. Staff funded four projects specifically related to reduction of waste with hazardous constituents, and LANS won four national awards for pollution prevention efforts from the National Nuclear Security Administration (NNSA). In FY13, there was no hazardous, mixedtransuranic (MTRU), or mixed low-level (MLLW) remediation waste generated at the Laboratory. More hazardous waste, MTRU waste, and MLLW was generated in FY13 than in FY12, and the majority of the increase was related to MTRU processing or lab cleanouts. These accomplishments and analysis of the waste streams are discussed in much more detail within this report.

The DIII-D tokamak research program is managed by General Atomics (GA) for the US Department of Energy (DOE). Major program participants include GA, Lawrence Livermore National Laboratory (LLNL), Oak Ridge National Laboratory (ORNL), and the University of California together with several other national laboratories and universities. The DIII-D is a moderate sized tokamak with great flexibility and extremely capable subsystems. The primary goal of the DIII-D tokamak research program is to provide data for development of a conceptual physics blueprint for a commercially attractive fusion power plant. In so doing, the DIII-D program provides physics and technology R&D output to aid the International Thermonuclear Experimental Reactor (ITER) and the Princeton Tokamak Physics Experiment (TPX) projects. Specific DIII-D objectives include the achievement of steady-state plasma current as well as the demonstration of techniques for radio frequency heating, divertor heat removal, particle exhaust and tokamak plasma control. The DIII-D program is addressing these objectives in an integrated fashion in plasmas with high beta and with high confinement. The long-range plan is organized with two principal elements, the development of an advanced divertor and the development of advanced tokamak concepts. These two elements have a common goal: an improved demonstration reactor (DEMO) with lower cost and smaller size than present DEMO concepts. In order to prepare for this long-range development, in FY94 the DIII-D research program concentrated on three major areas: Divertor and Boundary Physics, Advanced Tokamak studies, and Tokamak Physics.

The US Department of Energy (DOE) is in the process of completing a survey of environmental problems, referred to as the Environmental Survey, at their facilities across the country. The DOE Risk Information System (RIS) is being used to prioritize these environmental problems identified in the Environmental Survey's findings. This report contains a discussion of site-specific public health risk parameters and the rationale for their inclusion in the RIS. These parameters are based on computed potential impacts obtained with the Multimedia Environmental Pollutant Assessment System (MEPAS). MEPAS is a computer-based methodology for evaluating the potential exposures resulting from multimedia environmental transport of hazardous materials. This report has three related objectives: document the role of MEPAS in the RIS framework, report the results of the analysis of alternative risk parameters that led to the current RIS risk parameters, and describe analysis of uncertainties in the risk-related parameters. 20 refs., 17 figs., 10 tabs.

Simultaneous Pursuit of Discovery and Invention in the US Department of Energy

2015 OTC Conference Review The effects of oil price volatility on operators and service companies, technological advances, safety and environmental risks, economic and regulatory impacts, and sustainability were highlighted in the sessions and discussions during the annual Offshore Technology Conference (OTC) held 4–7 May in Houston. More than 94,700 attendees from 130 countries gathered to exchange ideas and opinions. It is the sixth largest attendance in the conference’s 47-year history. This year’s conference also had 2,682 companies exhibiting, up from 2,568 in 2014, representing 37 countries. International companies made up 42% of exhibitors. The event featured 11 panel sessions, 29 executive keynote presentations at luncheons and breakfasts, and nearly 300 technical paper presentations. Speakers from major, independent, and national oil companies, federal and regional government officials, and academics presented their views on a variety of topics such as future industry directions, operational integrity, and risk management. North American Energy Outlook The North American energy outlook, simultaneously reflecting surging production and resource abundance and the uncertainty surrounding the steep decline in oil prices, Mexican energy reform, and the future shape of regulation, was the focus of panelists from Canada, Mexico, and the United States in one of the sessions. Gamal Hassan, chief executive officer (CEO) of ADH International, described North America as being “at an inflection point in energy” and said, “The biggest question is how the US [industry] will restructure itself.” Gustavo Hernandez-Garcia, director general of Pemex Exploration and Production, forecast a moderate recovery in oil prices late this year through 2016 but with significant long-term risks. Addressing the changes at Pemex as Mexico undertakes industry reform, Hernandez said the company needs to improve its cash flow, is divesting itself of noncore assets, and is looking to acquire complementary assets “on the cheap” while prices are down. “We are trying to produce more value barrels rather than just volume,” he said. Hernandez outlined three possible outcomes for Mexican energy reform: 1) Achieving full potential and being competitive in the market; 2) Mixed results with part of the company being market competitive and part continuing to rely on state support; and 3) Unrealized potential because of “slow-motion implementation.” He said that Pemex prefers the first scenario. Paula Gant, deputy assistant secretary for oil and natural gas at the US Department of Energy (DOE) Office of Fossil Energy, stressed the importance of the ongoing trilateral cooperation on energy between the US, Canada, and Mexico and pointed to “the robust and resilient infrastructure” of the three countries’ energy systems. The continent’s oil and gas resources are abundant, and the US DOE is focused on the three countries “working together to maximize this regional abundance,” Gant said. To achieve the potential held by the continent’s resource base depends on maintaining public confidence, and the US DOE plays a critical role in this by providing “a solid scientific base” for public policy decisions, Gant said. David Ramsay, government minister of the Northwest Territories (NWT), Canada, spoke on unlocking the energy potential of the territorial area. The NWT hold shale oil resources estimated at 3 billion to 5 billion bbl, and Trans- Canada’s proposed Mackenzie Gas Project would build a 750-mile pipeline to link 80 Tcf of natural gas in place in the NWT with North American markets, he said.

Historical and continuing US Department of Energy (USDOE) operations have not only contaminated the environment but have altered the landscape as well as habitat quality and quantity. The changes in the landscape that have occurred within USDOE facilities may be as important as assessing the effects resulting from the release of chemical contaminants into the environment. We examined several methods from habitat analysis and landscape ecology for their possible application to ecological risk assessment at selected USDOE facilities. In an earlier manuscript, we presented landscape ecological methods that could be used in ecological risk assessment. In this manuscript, we present results of adapting Habitat Suitability Index (HSI) models, developed for habitat suitability analysis, for use in ecological risk assessment at USDOE facilities. The Oak Ridge Reservation (ORR) in eastern Tennessee and the Savannah River Site (SRS) in western South Carolina were selected as representative USDOE facilities. HSI models were developed in a probabilistic format for species common to both facilities [white-tailed deer (Odocoileus virginianus) and pileated woodpecker (Dryocopus pileatus)] and species exclusive to each facility [red-spotted newt (Notophthalmus viridescens viridescens) for the ORR and American alligator (Alligator mississippiensis) for the SRS]. Results indicate that HSI models could effectively be used to assess ecological risks. Spatially-explicit HSI models and landscape-scale ecological models that provide the necessary spatial component for more realistic risk assessments that could be used in ecological risk assessments at a variety of federal facilities, such as USDOE facilities, are presented as a result of a literature review and an internet search. The combination and integration of methods from habitat suitability analysis and ecological models presented in this manuscript and methods from landscape ecology presented in an earlier manuscript represent an effective set of tools that could be used to assess ecological risks at USDOE facilities; these tools could also be used at other locations.