We present error mitigation (EM) techniques for noisy intermediate-scale quantum computers (QC) based on density matrix purification and perturbative corrections to the target energy. We incorporate ...this scheme into the variational quantum eigensolver (VQE) and demonstrate chemically-accurate ground state energy calculations of various alkali metal hydrides using IBM quantum computers. Both the density matrix purification improvements and the perturbative corrections require only meager classical computational resources, and are conducted exclusively as post-processing of the measured density matrix. The improved density matrix leads to better simulation accuracy at each step of the variational optimization, resulting in a better input into the next optimization step without additional measurements. Adding perturbative corrections to the resulting energies further increases the accuracy, and decreases variation between consecutive measurements. These EM schemes allow for previously unavailable levels of accuracy over remote QC resources.
We present ExaTN (Exascale Tensor Networks), a scalable GPU-accelerated C++ library which can express and process tensor networks on shared- as well as distributed-memory high-performance computing ...platforms, including those equipped with GPU accelerators. Specifically, ExaTN provides the ability to build, transform, and numerically evaluate tensor networks with arbitrary graph structures and complexity. It also provides algorithmic primitives for the optimization of tensor factors inside a given tensor network in order to find an extremum of a chosen tensor network functional, which is one of the key numerical procedures in quantum many-body theory and quantum-inspired machine learning. Numerical primitives exposed by ExaTN provide the foundation for composing rather complex tensor network algorithms. We enumerate multiple application domains which can benefit from the capabilities of our library, including condensed matter physics, quantum chemistry, quantum circuit simulations, as well as quantum and classical machine learning, for some of which we provide preliminary demonstrations and performance benchmarks just to emphasize a broad utility of our library.
The opportunities afforded by near-term quantum computers to calculate the ground-state properties of small molecules depend on the structure of the computational ansatz as well as the errors induced ...by device noise. Here we investigate the behavior of these noisy quantum circuits using numerical simulations to estimate the accuracy and fidelity of the prepared quantum states relative to the ground truth obtained by conventional means. We implement several different types of ansatz circuits derived from unitary coupled cluster theory for the purposes of estimating the ground-state energy of sodium hydride using the variational quantum eigensolver algorithm. We show how relative error in the energy and the fidelity scale with the levels of gate-based noise, the internuclear configuration, the ansatz circuit depth, and the parameter optimization methods.
Inflammatory bowel diseases (IBD) increase the risk of developing colorectal cancer. Dietary components that reduce inflammation are associated with lower cancer risk. The long-chain omega-3 fatty ...acid docosahexaenoic acid (DHA) is present in fish oil and has potent anti-inflammatory properties. The objective of this study is to determine whether dietary fish oil enriched with DHA (DFO) could reduce experimentally induced colitis and colon cancer risk in a mouse model. When SMAD3-/- mice are exposed to Helicobacter hepaticus, mild colitis is observed 4 weeks postinfection. Mice were fed isocaloric diets modified to include corn oil, safflower oil, or DFO (doses ranging from 0.75% to 6.00%) as the fatty acid source for 8 weeks. Mice were gavaged with H. hepaticus; DFO feeding was continued; and mice were sacrificed 4 weeks after infection. The colon and cecum were collected for histopathology. Spleens and mesenteric lymph nodes were collected and analyzed for T-cell populations using flow cytometry. Contrary to expectations, DFO induced severe colitis and adenocarcinoma formation. DFO consumption was associated with decreased CD8(+) cell frequency and diminished CD69 expression on CD4(+) and CD8(+) T-cell populations. Mice consuming DFO also exhibited higher FoxP3(+) CD25(+) CD4(+) T regulatory cell frequency, FoxP3 expression, and altered L-selectin expression during infection. We concluded that DFO-fed mice may be less equipped to mount a successful response to H. hepaticus infection, increasing colon cancer risk. These results support the need to establish a tolerable upper limit for DHA intake particularly in the context of chronic inflammatory conditions such as IBD.
Princeville, NC, is the oldest town chartered by Blacks in America. Founded as Freedom Hill in 1865 and incorporated as Princeville in 1885, the town continues to be predominantly African American ...today. Built on the unwanted and flood-prone lands adjacent to the Tar River, Princeville has flooded multiple times throughout its history, including after Hurricane Floyd in 1999 and Hurricane Matthew in 2016. Because of the town’s historical significance, residents and town officials alike have been reluctant to accept offers for widespread buyouts from the government. Despite having limited financial resources and political clout, the town has developed a unique approach to managed retreat while rebuilding from Matthew—one that emphasizes the importance of historical sites while also recognizing the need to relocate residents out of harm’s way from future floods. This manuscript uses a historical and narrative approach to examine how Princeville’s unique history, and the relationship between the town and the Tar River, play important roles in the town’s decisions regarding retreat and redevelopment in the aftermath of major flooding events. We highlight the voices of current residents, including leaders, as well as the structural and cultural conditions that both constrain and enable the town’s collective agency. While focused on the present day, this case study is historically informed, using oral histories and archival documents.
Quantum computing is emerging as a remarkable technology that offers the possibility of achieving major scientific breakthroughs in many areas. Here, by leveraging the unique features of quantum ...mechanics, quantum computers may be instrumental in advancing many areas, including science, energy, defense, medicine, and finance. This includes solving complex problems whose solution lies well beyond the capacity of contemporary and even future supercomputers that are based on conventional computing technologies. As a foundation for future generations of computing and information processing, quantum computing represents an exciting area for developing new ideas in computer science and computational engineering.
We present qcor—a language extension to C++ and compiler implementation that enables heterogeneous quantum-classical programming, compilation, and execution in a single-source context. Our work ...provides a first-of-its-kind C++ compiler enabling high-level quantum kernel (function) expression in a quantum-language agnostic manner, as well as a hardware-agnostic, retargetable compiler workflow targeting a number of physical and virtual quantum computing backends. qcor leverages novel Clang plugin interfaces and builds upon the XACC system-level quantum programming framework to provide a state-of-the-art integration mechanism for quantum-classical compilation that leverages the best from the community at-large. qcor translates quantum kernels ultimately to the XACC intermediate representation, and provides user-extensible hooks for quantum compilation routines like circuit optimization, analysis, and placement. This work details the overall architecture and compiler workflow for qcor, and provides a number of illuminating programming examples demonstrating its utility for near-term variational tasks, quantum algorithm expression, and feed-forward error correction schemes.
QCOR Mintz, Tiffany M.; McCaskey, Alexander J.; Dumitrescu, Eugene F. ...
ACM journal on emerging technologies in computing systems,
04/2020, Letnik:
16, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Quantum computing (QC) is an emerging computational paradigm that leverages the laws of quantum mechanics to perform elementary logic operations. Existing programming models for QC were designed with ...fault-tolerant hardware in mind, envisioning stand-alone applications. However, the susceptibility of near-term quantum computers to noise limits their stand-alone utility. To better leverage limited computational strengths of noisy quantum devices, hybrid algorithms have been suggested whereby quantum computers are used in tandem with their classical counterparts in a heterogeneous fashion. This
modus operandi
calls out for a programming model and a high-level programming language that natively and seamlessly supports heterogeneous quantum-classical hardware architectures in a single-source-code paradigm. Motivated by the lack of such a model, we introduce a language extension specification, called
QCOR
, which enables single-source quantum-classical programming. Programs written using the QCOR library–based language extensions can be compiled to produce functional hybrid binary executables. After defining QCOR’s programming model, memory model, and execution model, we discuss how QCOR enables variational, iterative, and feed-forward QC. QCOR approaches quantum-classical computation in a hardware-agnostic heterogeneous fashion and strives to build on best practices of high-performance computing. The high level of abstraction in the language extension is intended to accelerate the adoption of QC by researchers familiar with classical high-performance computing.
This study was conducted to evaluate the effects of deepstack processing broiler poultry litter with or without aeration on enteric bacteria survival (Trial 1), and to determine the optimum aeration ...period (Trial 2) and aeration frequency (Trial 3) to control excessive heating of litter during the deepstacking process. The effects of deepstacked litter temperature on bacteria survival and on chemical compositions of the litter were monitored. In Trial 1,
E. coli,
Salmonella enteriticis and
Shigella sonnei were intentionally inoculated into the litter and their survival was monitored with time of litter processing. In Trial 2, litter was deepstacked and aerated once a day from the initial day or from the day when maximum stack temperature was reached and started to decrease to the end of processing period. In Trial 3, litter was deepstacked and aerated once or twice a day from the day after maximum stack temperature was attained until constant temperature was attained. During the deepstacking process of litter pathogenic bacteria were eliminated between the 2nd and 4th day of deepstacking. This phenomenon occurred apparently not only by high heat generated, but also by other potential factors, such as ammonia and microbial competition. Aeration resulted in the heat dissipation and early temperature reduction of deepstacked litter. The optimum aeration procedure to avoid excessive heating of deepstacked litter was to aerate once a day after the stack temperature reached its maximum at the early stage of deepstacking and for 3 days or until the stack temperature dropped off and reached constancy. This aerating frequency and duration did not negatively affect the chemical composition of deepstacked litter. These results suggest that poultry litter properly deepstacked, with or without aeration, to ensure the elimination of enteric bacterial pathogens may be fed at least 10 days earlier than the 21-day deepstacking period previously recommended.
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