3,003 research outputs found
Zero-noise Extrapolation Assisted with Purity for Quantum Error Mitigation
Quantum error mitigation is a technique used to post-process errors occurring
in the quantum system, which reduces the expected errors and achieves higher
accuracy. One method of quantum error mitigation is zero-noise extrapolation,
which involves amplifying the noise and then extrapolating the observable
expectation of interest back to a noise-free point. This method usually relies
on the error model of the noise, as error rates for different levels of noise
are assumed during the noise amplification process. In this paper, we propose
that the purity of output states in noisy circuits can assist in the
extrapolation process, eliminating the need for assumptions about error rates.
We also introduce the quasi-polynomial model from the linearity of quantum
channel for extrapolation of experimental data, which can be reduced to other
proposed models. Furthermore, we verify our purity-assisted zero-noise
extrapolation by performing numerical simulations and experiments on the online
public quantum computation platform, Quafu, to compare it with the routine
zero-noise extrapolation and virtual distillation methods. Our results
demonstrate that this modified method can suppress the random fluctuation of
operator expectation measurement, and effectively reduces the bias in
extrapolation to a level lower than both the zero-noise extrapolation and
virtual distillation methods, especially when the error rate is moderate
First report on the occurrence of Rickettsia slovaca and Rickettsia raoultii in Dermacentor silvarum in China
10.1186/1756-3305-5-19Parasites and Vectors511
Brusatol
The title compound, C26H32O11, is composed of an α,β-unsaturated cyclohexanone ring (A), two cyclohexane rings (B and C), a six-membered lactone ring (D) and tetrahydrofuran ring (E). Ring A exists in a half-chair conformation with a C atom displaced by 0.679 (2) Å from the mean plane through the remaining five atoms. Ring B exists in a normal chair conformation. Both rings C and D exist in a twisted-chair conformation due to the O-atom bridge and the carbonyl group in rings C and D, respectively. Ring E shows an envelope conformation with a C atom displaced by 0.761 (1) Å from the mean plane through the remaining five atoms. The ring junctions are A/B trans, B/C trans, C/D cis and D/E cis. An intramolecular O—H⋯O hydrogen bond occurs. In the crystal, O—H⋯O hydrogen bonds involving the hydroxy, lactone and ester groups and C—H⋯O interactions are observed
Secohellebrigeninamide
The title compound, C26H37NO5, was the reaction product of hellebrigenin with N,N-dimethylformamide. It consists of three cyclohexane rings (A, B and C), one five-membered ring (D) and one dihydropyran ring (E). The stereochemistry of the ring junctions is is A/B cis, B/C trans, C/D cis and C/E trans. The cyclohexane rings A, B and C have chair conformations. Both the five-membered ring D and the dihydropyran ring adopt an envelope conformation. Two orientations are found for the aldehyde group with occupancies of 0.608 (10) and 0.392 (10). In the crystal, short O—H⋯O hydrogen bonds and short C—H⋯O contacts involving the hydroxy group, terminal methyl group and carbonyl group link the molecules into a three-dimensional network
Data query mechanism based on hash computing power of blockchain in internet of things
Funding: This work is supported by the NSFC (61772280, 61772454, 61811530332, 61811540410), the PAPD fund from NUIST. This work was funded by the Researchers Supporting Project No. (RSP-2019/102) King Saud University, Riyadh, Saudi Arabia. Jin Wang and Osama Alfarraj are the corresponding authors. Acknowledgments: We thank Researchers Supporting Project No. (RSP-2019/102) King Saud University, Riyadh, Saudi Arabia for funding this paper. Author Contributions: Y.R., F.Z. and O.A. conceived the mechanism design and wrote the paper, P.K.S. built the models. T.W. and A.T. developed the mechanism, J.W. and O.A. revised the manuscript. All authors have read and agreed to the published version of the manuscript.Peer reviewedPublisher PD
Poly[[tetraaqua-μ4-fumarato-di-μ3-fumarato-dineodymium(III)] trihydrate]
The title coordination polymer, {[Nd2(C4H2O4)3(H2O)4]·3H2O}, was synthesized by the reaction of neodymium(III) nitrate hexahydrate with fumaric acid in a water–methanol (7:3) solution. The asymmetric unit comprises two Nd3+ cations, three fumarate dianions (L
2−), four aqua ligands and three uncoordinated water molecules. The carboxylate groups of the fumarate dianions exhibit different coordination modes. In one fumarate dianion, two carboxylate groups chelate two Nd3+ cations, while one of the O atoms is coordinated to another Nd3+ cation. Another fumarate dianion bridges three Nd3+ cations: one of the carboxylate groups chelates one Nd3+ cation, while the other carboxylate group bridges two Nd3+ cations in a monodentate mode. The third fumarate dianion bridges four Nd3+ cations, where one of the carboxylate groups chelates one Nd3+ cation and coordinates in a monodentate mode to a second Nd3+, while the second carboxylate groups bridges two Nd3+ cations in a monodentate mode and one O atom is coordinated to one Nd3+ cation. The Nd3+ cations are in a distorted tricapped–trigonal prismatic environment and coordinated by seven O atoms from the fumarate ligands and two O atoms from water molecules. The Nd3+ cations are linked by two carboxylate O atoms and two carboxylate groups, generating infinite Nd–O chains to form a three-dimensional framework. There are O—H⋯O and C—H⋯O hydrogen-bonding interactions between the coordinated and uncoordinated water molecules and carboxylate O atoms
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