Search

Implementation of an error-corrected quantum computer is believed to require a quantum processor with a million or more physical qubits, and, in order to run such a processor, a quantum control system of similar scale will be required. Such a controller will need to be integrated within the cryogenic system and in close proximity with the quantum processor in order to make such a system practical. Here, we present a prototype cryogenic CMOS quantum controller designed in a 28-nm bulk CMOS process and optimized to implement a 16-word (4-bit) XY gate instruction set for controlling transmon qubits. After introducing the transmon qubit, including a discussion of how it is controlled, design considerations are discussed, with an emphasis on error rates and scalability. The circuit design is then discussed. Cryogenic performance of the underlying technology is presented, and the results of several quantum control experiments carried out using the integrated controller are described. This article ends with a comparison to the state of the art and a discussion of further research to be carried out. It has been shown that the quantum control IC achieves promising performance while dissipating less than 2 mW of total ac and dc power and requiring a digital data stream of less than 500 Mb/s.

The performance of superconducting circuits for quantum computing is limited by materials losses. In particular, coherence times are typically bounded by two-level system (TLS) losses at single photon powers and millikelvin temperatures. The identification of low loss fabrication techniques, materials, and thin film dielectrics is critical to achieving scalable architectures for superconducting quantum computing. Superconducting microwave resonators provide a convenient qubit proxy for assessing performance and studying TLS loss and other mechanisms relevant to superconducting circuits such as non-equilibrium quasiparticles and magnetic flux vortices. In this review article, we provide an overview of considerations for designing accurate resonator experiments to characterize loss, including applicable types of loss, cryogenic setup, device design, and methods for extracting material and interface losses, summarizing techniques that have been evolving for over two decades. Results from measurements of a wide variety of materials and processes are also summarized. Lastly, we present recommendations for the reporting of loss data from superconducting microwave resonators to facilitate materials comparisons across the field., Comment: Review Article

Reverse electrodialysis (RED) is an electrically driven process for the extraction of usable energy from the Gibbs free energy of mixing. Past research efforts have focused on the improvement of power density through higher voltages, large cell numbers, and overall reduction of stack resistance, yet the process remains far from optimized. One of the principal problems is the shadow spacer effect where limited conductivity near the spacer decreases the amount of electrical transport. We have improved this technology by incorporating ion exchange wafers in each cell, shortening the diffusion pathways, limiting the shadow spacer effect, and obtaining net power densities of approximately 0.32 W/m 2 for reverse electrodeionization (REDI) compared to 0.01 W/m 2 for the RED case. Further, we have found that applying voltage to the system gives an increase in the overall power extraction efficiency due to wafer optimization and the non-ohmic behavior at low voltages. This is the first study incorporating electrodeionization techniques in RED systems. We also investigated the use of REDI in hydraulic fracturing and obtained a net power density of approximately 0.79 W/m 2 using produced water. This technology could be utilized for processing of produced water from hydraulic fracturing operations to provide some of the power used at the well site (when mixing with fresh water for re-fracking) with no greenhouse gas emissions. Using REDI at fracking sites, an industrial process that has been mired by environmental concerns can take positive steps toward developing and adopting sustainable practices.

While quantum processors are typically cooled to $\lt 25$ mK to avoid thermal disturbances to their delicate quantum states, all qubits still suffer decoherence and gate errors. As such, quantum error correction is needed to fully harness the power of quantum computing (QC). Current projections indicate that $\gt 1,000$ physical qubits will be required to encode one error-corrected qubit [1]. Implementing a system with 1,000 error-corrected qubits will likely require moving from the contemporary paradigm where control and readout of the quantum processor is carried out using racks of room temperature electronics to one in which integrated control/readout circuits are located within the cryogenic environment and connected to the quantum processor through superconducting interconnects [2]. This is a major challenge, as the cryo ICs must be high performance and very low power (eventually $\lt 1$ mW/qubit). In this paper, we report the design and system-level characterization of a prototype cryo-CMOS IC for performing XY gate operations on transmon (XMON) qubits.

This Research to Practice work-in-progress paper presents the development and initial implementation of a project assigned to first-year students in an Introduction to Engineering Design course at Penn State Erie, the Behrend College. Traditionally, students learn about the engineering design process through design-only projects such as redesigning an electric toothbrush or selecting components for a renewable-energy powered water well. Although these projects were hands-on, they did not include students converting the design concept to a tangible product. In fall 2017, a new project using Arduino kits was introduced to the course. Students were asked to build a line-following robot car with a chassis of their own design as long as it kept the wires and circuit board inside. In designing the robot car, students sketched design concepts, selected the best one, and used low-fidelity materials to create beta prototypes. Once they had a working chassis, students created it in Autodesk Inventor and realized the final design of the chassis through 3D printing and laser cutting.To measure if the new hands-on project has an impact on student learning, students were asked to report which instructional activity they learn best from and how they relate engineering design to real life before and after the project. We found that at the completion of the robot car project, students became less in favor of lecture-based instructions. Rather, they have developed a preference in figuring out the solutions on their own. Students highly appreciated the open-ended design project and the hands-on experience of building a prototype.As with any project carried out for the first time, the robot car design project ran into some technical difficulties. Nonetheless, students reported that this hands-on project is fun and rewarding, and they now have a much deeper understanding of the engineering design process behind every product in the market. This paper discusses the student design project in detail, including the results of the project based off of student surveys and faculty observations, and suggestions for improvement and implementation at other schools.

We develop a high speed on-chip flux measurement using a capacitively shunted SQUID as an embedded cryogenic transducer and apply this technique to the qualification of a near-term scalable printed circuit board (PCB) package for frequency tunable superconducting qubits. The transducer is a flux tunable LC resonator where applied flux changes the resonant frequency. We apply a microwave tone to probe this frequency and use a time-domain homodyne measurement to extract the reflected phase as a function of flux applied to the SQUID. The transducer response bandwidth is 2.6 GHz with a maximum gain of $\rm 1200^\circ/\Phi_0$ allowing us to study the settling amplitude to better than 0.1%. We use this technique to characterize on-chip bias line routing and a variety of PCB based packages and demonstrate that step response settling can vary by orders of magnitude in both settling time and amplitude depending on if normal or superconducting materials are used. By plating copper PCBs in aluminum we measure a step response consistent with the packaging used for existing high-fidelity qubits.

Josephson junctions form the essential non-linearity for almost all superconducting qubits. The junction is formed when two superconducting electrodes come within $\sim$1 nm of each other. Although the capacitance of these electrodes is a small fraction of the total qubit capacitance, the nearby electric fields are more concentrated in dielectric surfaces and can contribute substantially to the total dissipation. We have developed a technique to experimentally investigate the effect of these electrodes on the quality of superconducting devices. We use $\lambda$/4 coplanar waveguide resonators to emulate lumped qubit capacitors. We add a variable number of these electrodes to the capacitive end of these resonators and measure how the additional loss scales with number of electrodes. We then reduce this loss with fabrication techniques that limit the amount of lossy dielectrics. We then apply these techniques to the fabrication of Xmon qubits on a silicon substrate to improve their energy relaxation times by a factor of 5.

In 1998, MacMillan Bloedel (now Weyerhaeuser) committed to a system of Stewardship Zones and to replacing clearcutting with variable retention over its 1.1 million ha coastal tenure. The decision began a grand experiment in forest planning and practice, which the company committed to monitor and refine through an adaptive management program. The program was most challenging to design and implement for biodiversity. Key elements of the program were: creating a criterion and associated indicators, developing a list of focused questions, and developing a cost-effective design for monitoring and learning. The final step in any adaptive management program is linking the monitoring back to specific management actions. We provide examples of successful linkages back for each of the three major indicators of biodiversity: ecosystem representation, habitat structure, and organisms. We discuss major difficulties that arise when developing management responses to the complex issue of sustaining biological diversity and note four major challenges to the design and implementation of any adaptive management program. Key words: adaptive management, biodiversity, indicators, monitoring, variable retention harvesting

Adaptive management is a key component of a forest project being implemented across all of Weyerhaeuser's coastal forest tenures. This project uses two main tools to accomplish the British Columbia (BC) Coastal Group's ecological and socio-economic goals: variable retention (VR) harvesting and broad zoning of the land base. The adaptive management program was designed to examine the effectiveness of retention systems and zoning in maintaining those forest attributes necessary to sustain biological richness and essential ecosystem functions, such as nutrient transfer, energy flow, decomposition, and dispersal of seeds, spores, and animals. The program is grounded on three biological indicators evaluated in both operational and experimental contexts: 1) representation of habitat types in a relatively unmanaged state to ensure that little-known species are retained; 2) structure of stands and landscapes to ensure that key elements are present through time; and 3) indicator organisms to track whether retaining structures and patterns, while addressing representation, will maintain species and populations whose life needs are well understood. Representation of ecosystems in unmanaged conditions has been examined. Habitat structure is being assessed in VR blocks and in unmanaged blocks. Studies on several organisms (breeding birds, owls, gastropods, amphibians, bryophytes, lichen, squirrels, mycorrhizae, and carabid beetles) have been underway for various lengths of time. These studies collected baseline information to begin comparisons of the effectiveness of the various types of VR for maintaining biological richness. The current focus in the adaptive management program is refining the lists of specific elements to monitor and beginning to create tools to help extrapolate relationships and findings over large areas and long time frames, with the expectation of operational implementation in 2003. The first two years of pilot work are also being used to examine how the results will link to management practices to strengthen areas that most need improvement. This paper describes three indicators used in Weyerhaeuser's adaptive management program. Key words: adaptive management, variable retention harvesting, indicators for monitoring forests

Complex integrated circuits require multiple wiring layers. In complementary metal-oxide-semiconductor processing, these layers are robustly separated by amorphous dielectrics. These dielectrics would dominate energy loss in superconducting integrated circuits. Here, we describe a procedure that capitalizes on the structural benefits of inter-layer dielectrics during fabrication and mitigates the added loss. We use a deposited inter-layer dielectric throughout fabrication and then etch it away post-fabrication. This technique is compatible with foundry level processing and can be generalized to make many different forms of low-loss wiring. We use this technique to create freestanding aluminum vacuum gap crossovers (airbridges). We characterize the added capacitive loss of these airbridges by connecting ground planes over microwave frequency λ/4 coplanar waveguide resonators and measuring resonator loss. We measure a low power resonator loss of ∼3.9 × 10−8 per bridge, which is 100 times lower than that of dielectric supported bridges. We further characterize these airbridges as crossovers, control line jumpers, and as part of a coupling network in gmon and fluxmon qubits. We measure qubit characteristic lifetimes (T1s) in excess of 30 μs in gmon devices.

We present a fabrication process for fully superconducting interconnects compatible with superconducting qubit technology. These interconnects allow for the three dimensional integration of quantum circuits without introducing lossy amorphous dielectrics. They are composed of indium bumps several microns tall separated from an aluminum base layer by titanium nitride which serves as a diffusion barrier. We measure the whole structure to be superconducting (transition temperature of 1.1 K), limited by the aluminum. These interconnects have an average critical current of 26.8 mA, and mechanical shear and thermal cycle testing indicate that these devices are mechanically robust. Our process provides a method that reliably yields superconducting interconnects suitable for use with superconducting qubits.

Many superconducting qubits are highly sensitive to dielectric loss, making the fabrication of coherent quantum circuits challenging. To elucidate this issue, we characterize the interfaces and surfaces of superconducting coplanar waveguide resonators and study the associated microwave loss. We show that contamination induced by traditional qubit lift-off processing is particularly detrimental to quality factors without proper substrate cleaning, while roughness plays at most a small role. Aggressive surface treatment is shown to damage the crystalline substrate and degrade resonator quality. We also introduce methods to characterize and remove ultra-thin resist residue, providing a way to quantify and minimize remnant sources of loss on device surfaces.

The regions of the world using operational seedling testing to any significant extent are Canada, Britain, Sweden, and the Pacific Northwest region of the United States. Testing has been used operationally for batch culling (to ensure quality), as well as for research into improved nursery cultural practices. Savings from testing for seedling survival are substantial. However, growth gains from operational testing are more tenuous. Reduced rotation lengths and lower weeding costs are more likely to be associated with planting larger stock, rather than planting stock with higher physiological quality.

Superconducting microwave circuits based on coplanar waveguides (CPW) are susceptible to parasitic slotline modes which can lead to loss and decoherence. We motivate the use of superconducting airbridges as a reliable method for preventing the propagation of these modes. We describe the fabrication of these airbridges on superconducting resonators, which we use to measure the loss due to placing airbridges over CPW lines. We find that the additional loss at single photon levels is small, and decreases at higher drive powers., 8 pages and 7 figures including supplementary information

We demonstrate a lumped-element Josephson parametric amplifier, using a single-ended design that includes an on-chip, high-bandwidth flux bias line. The amplifier can be pumped into its region of parametric gain through either the input port or through the flux bias line. Broadband amplification is achieved at a tunable frequency $\omega/2 \pi$ between 5 to 7 GHz with quantum-limited noise performance, a gain-bandwidth product greater than 500 MHz, and an input saturation power in excess of -120 dBm. The bias line allows fast frequency tuning of the amplifier, with variations of hundreds of MHz over time scales shorter than 10 ns.

Background: One of the Joint Commission on Accreditation of Healthcare Organization's National Patient Safety Goals is for hospitals to accurately and completely reconcile patients' medications. Unfortunately, medication histories in charts might bc inaccurate and incomplete. In a thorough medication history, each medication should match a particular reported medical condition. The use of medications without a clear reported indication is of particular concern and has bccn associated with inappropriate use and polypharmacy. Objectives: The purposes of this study were to evaluate the occurrence of discrepancies between home medications listed in hospital admission notes and patients' reported medical conditions and to describe the types of medications most often identified as not having a corresponding indication. Methods: In this retrospective observational study, data were included from adult patients (≥18 years of age) who were receiving ≥3 home medications on admission to medical wards at a university hospital during a 6-month period. Each home medication listed in the admission note, together with any preadmission paperwork, was matched with an indication listed in the note. Medications were deemed unspecified if an indicated disease state or condition for the medication was not reported. Results: Data from 121 patients were included. The majority (91.7%) of the patients were admitted to an internal medicine service. Eighty-four patients (69.4%) had ≥1 unspecified medication listed in the admission note. Patients with ≥1 unspecified home medication reported taking a signifcantly higher number of home medications (10.2 [4.5] vs 7.5 [3.5] in those without unspecified medications; P = 0.007). Thirty-two patients (26.4%) were receiving proton pump inhibitors or histamine type 2 antagonists without a reported indication. Seventeen patients (14.0%) were receiving selective scrotonin rcuptakc inhibitors without a reported indication. Conclusions: Nearly 70% of patients admitted to a medical ward had ≥1 unspecified medication listed in the admission note. Based on these results, health care professionals must bc careful to obtain and document complete medication histories with matching indications.

Modern telecommunications deployment increasingly involves the use of remote sites. Equipment is housed in enclosures that range in size and scope from large concrete buildings containing entire switches to small cabinets containing a few lines of transmission equipment. In most cases, reserve energy during AC power failures is supplied from lead acid batteries collocated with the electronics within the enclosure. The fact that all lead acid batteries generate hydrogen continuously during their operation is an important design parameter for both the enclosure, and the equipment which the batteries are designed to support. While much published material has dealt with VRLA battery operational issues such as hydrogen evolution and thermal runaway from a design and engineering viewpoint, this investigation has attempted to represent a users perspective. In determining the capabilities and limitations of both the batteries and their end users the paper attempts to present some real world principles to aid successful applications. While predominantly focussing on wireless, such principles could also apply to other outside plant type applications. >

Venous thromboembolic complications occur in 50% to 70% of patients undergoing total hip arthroplasty if no prophylactic regimen is used. Because enoxaparin and warfarin are useful for extended outpatient prophylaxis, the objective of this study was to determine which of these agents is most cost effective in preventing venous thromboembolic complications. A decision tree analysis was developed to simulate a hypothetical cohort of patients with total hip arthroplasty. The analysis considered home health care services to perform monitoring and compliance verification. Accounting for prophylactic failures and treatment complications, results showed that enoxaparin maintained a cost effective advantage over warfarin for extended prophylaxis in the time after discharge and total hip arthroplasty ranging from 19 to 31 days after the patient was discharged from the hospital. The duration of cost effectiveness of enoxaparin was reduced to 14 to 17 days when home care services were excluded. These results indicated that approximately 3 weeks of outpatient therapy with enoxaparin is cost effective. With the cornerstone of managed care being cost efficiency in the provision of quality care, this conclusion warrants the development of integrated care strategies for the patient having orthopaedic surgery to achieve cost effective patient management.

Santosh Shenoy1 Carl Palmer2 Teresa Dunsworth3 Stephen McNatt4 1Department of Surgery, Louis A Johnson vA Medical Center, Clarksburg, wv, USA; 2Department of Medicine, west virginia University, General internal Medicine and Geriatrics, Morgantown, wv, USA; 3General internal Medicine and Geriatrics, west virginia University, Morgantown, wv, USA; 4Department of Surgery, wake Forest University Baptist Medical Center, winstonSalem, NC, USA

Follicular lymphoid hyperplasia of the hard palate is a reactive lymphoid proliferation which closely simulates the palatal lymphomas, both clinically and histologically. It is therefore imperative that the pathologist be familiar with the features that separate these two conditions. In equivocal cases like the present one, immunologic analysis would seem to be indicated to determine whether the lesion is monoclonal (neoplastic) or polyclonal (reactive).

Simulation of flow conditions within the operating regime of ramjet engines requires unique ground test capabilities. The blowdown facility is an economical method of meeting the high air mass flow and pressure ratio requirements. Vitiated air heaters provide a flexible and cost-effective method of simulating trajectory temperature variation. Adequate simulation of the inlet flow conditions in freejet tests plays an important role in engine development. Ramjet engine ground test requirements are discussed. Methods of simulating the applicable parameters in direct-connect and freejet tests are reviewed. Techniques and devices that have proved beneficial in meeting aerodynamic simulation requirements are described.

Energy savings from single retrofits in one- and two-unit homes have been investigated in order to provide more reliable estimates to homeowners who are considering a conservation investment. The samples were drawn from households that had financed conservation measures through a city/utility loan program. The sample groups studied to date are small, and the results are therfore tentative. Nevertheless, they provide an indication of the level of savings that is actually being achieved by these retrofits. Installation of high-efficiency furnaces and boilers produced an average savings of 14% of total weather-normalized annual gas use (NAC). These savings average about 80% of the predicted savings based on Minnesota's Residential Conservation Service (RCS) calculations. The median simple payback was 23 years. Wall insulation showed an average savings of 12% of NAC, with a median payback of 12 years. Adding attic insulation to houses where some insulation was present gave small savings that were not statistically different from zero. Actual savings for wall and attic insulation averaged about half of the predicted savings based on RCS calculations. These preliminary results corroborate our previous findings based on engineering estimates that wall insulation has higher savings and a faster payback than attic reinsulation, and that high-efficiency furnace/boiler installations are cost-effective primarily if the existing heating system needs to be replaced anyway.

We have studied HLA A, B, D, and DR and cytoplasmic islet cell antibodies (CICA) in 282 insulin-dependent diabetics (IDD) and 806 of their nondiabetic first-degree relatives. Fifty percent of the patients were positive in the first year of disease, but only 19% among those with disease for longer than 5 yr. No associations were found between CICA and HLA types, age at diagnosis, or family history. In the relatives of IDD patients CICA was present in (2.6%) of the sibs of the probands, (5.8%) of the parents, and (6.0%) of the children.

L'histoire vecue du desastre de la mine Springhill raconte l'etablissement et l'organisation d'un centre de secours et la participation dans ce desastre de l'equipe psychiatrique.Les auteurs decriv...

A histologic evaluation of punch biopsies from the osteotomy sites of five patients who had undergone a Le Fort I procedure was performed. Results of the evaluation indicated that the area between the segments healed with mature compact bone.