1,007 research outputs found
Quantum simulation of the quantum Rabi model in a trapped ion
The quantum Rabi model, involving a two-level system and a bosonic field
mode, is arguably the simplest and most fundamental model describing quantum
light-matter interactions. Historically, due to the restricted parameter
regimes of natural light-matter processes, the richness of this model has been
elusive in the lab. Here, we experimentally realize a quantum simulation of the
quantum Rabi model in a single trapped ion, where the coupling strength between
the simulated light mode and atom can be tuned at will. The versatility of the
demonstrated quantum simulator enables us to experimentally explore the quantum
Rabi model in detail, including a wide range of otherwise unaccessible
phenomena, as those happening in the ultrastrong and deep strong coupling
regimes. In this sense, we are able to adiabatically generate the ground state
of the quantum Rabi model in the deep strong coupling regime, where we are able
to detect the nontrivial entanglement between the bosonic field mode and the
two-level system. Moreover, we observe the breakdown of the rotating-wave
approximation when the coupling strength is increased, and the generation of
phonon wave packets that bounce back and forth when the coupling reaches the
deep strong coupling regime. Finally, we also measure the energy spectrum of
the quantum Rabi model in the ultrastrong coupling regime.Comment: 8 pages, 4 figure
Genuine N-wise Quantum Incompatibility in a High-Dimensional System
Quantum incompatibility is referred as the phenomenon that some quantum
measurements cannot be performed simultaneously, and is also used in various
quantum information tasks. However, it is still a challenge to certify whether
a given set of multiple high-dimensional measurements respects a specific
structure of incompatibility. To address this problem, we propose a modified
quantum state discrimination protocol that decomposes complex compatibility
structures into pair-wise ones and employs noise robustness to witness
incompatibility structures. Our method is capable of detecting genuine -wise
incompatibility and some specific general compatibility structures, as
demonstrated by our experimental verification of incompatibility structures of
mutually unbiased bases in a qutrit system. The experimental results show
that our approach is a direct and intuitive tool to witness incompatibility
structures in high-dimensional multi-measurement scenarios.Comment: 7 pages, 4 figure
Quantum Simulation Of The Quantum Rabi Model In A Trapped Ion
The quantum Rabi model, involving a two-level system and a bosonic field mode, is arguably the simplest and most fundamental model describing quantum light-matter interactions. Historically, due to the restricted parameter regimes of natural light-matter processes, the richness of this model has been elusive in the lab. Here, we experimentally realize a quantum simulation of the quantum Rabi model in a single trapped ion, where the coupling strength between the simulated light mode and atom can be tuned at will. The versatility of the demonstrated quantum simulator enables us to experimentally explore the quantum Rabi model in detail, including a wide range of otherwise unaccessible phenomena, as those happening in the ultrastrong and deep strong-coupling regimes. In this sense, we are able to adiabatically generate the ground state of the quantum Rabi model in the deep strong-coupling regime, where we are able to detect the nontrivial entanglement between the bosonic field mode and the two-level system. Moreover, we observe the breakdown of the rotating-wave approximation when the coupling strength is increased, and the generation of phonon wave packets that bounce back arid forth when the coupling reaches the deep strong-coupling regime. Finally, we also measure the energy spectrum of the quantum Rabi model in the ultrastrong-coupling regime.We thank Xiao Yuan, Xiongfeng Ma, Hyunchul Nha, Jiyong Park, Jaehak Lee, and M. S. Kim for useful discussions on the entanglement verification of the ground state. This work was supported by the National Key Research and Development Program of China under Grants No. 2016YFA0301900 and No. 2016YFA0301901 and the National Natural Science Foundation of China Grants No. 11374178, No. 11574002, and No. 11504197, MINECO/FEDER FIS2015-69983-P, Ramon y Cajal Grant No. RYC-2012-11391, and Basque Government IT986-16
Abstract Syntax Tree for Programming Language Understanding and Representation: How Far Are We?
Programming language understanding and representation (a.k.a code
representation learning) has always been a hot and challenging task in software
engineering. It aims to apply deep learning techniques to produce numerical
representations of the source code features while preserving its semantics.
These representations can be used for facilitating subsequent code-related
tasks. The abstract syntax tree (AST), a fundamental code feature, illustrates
the syntactic information of the source code and has been widely used in code
representation learning. However, there is still a lack of systematic and
quantitative evaluation of how well AST-based code representation facilitates
subsequent code-related tasks. In this paper, we first conduct a comprehensive
empirical study to explore the effectiveness of the AST-based code
representation in facilitating follow-up code-related tasks. To do so, we
compare the performance of models trained with code token sequence (Token for
short) based code representation and AST-based code representation on three
popular types of code-related tasks. Surprisingly, the overall quantitative
statistical results demonstrate that models trained with AST-based code
representation consistently perform worse across all three tasks compared to
models trained with Token-based code representation. Our further quantitative
analysis reveals that models trained with AST-based code representation
outperform models trained with Token-based code representation in certain
subsets of samples across all three tasks. We also conduct comprehensive
experiments to evaluate and reveal the impact of the choice of AST
parsing/preprocessing/encoding methods on AST-based code representation and
subsequent code-related tasks. Our study provides future researchers with
detailed guidance on how to select solutions at each stage to fully exploit
AST.Comment: submitted to ACM Transactions on Software Engineering and
Methodology. arXiv admin note: text overlap with arXiv:2103.10668 by other
author
A first-principles study of MgB2 (0001) surfaces
We report self-consistent {\it ab initio} calculations of structural and
electronic properties for the B- and Mg-terminated MgB (0001) surfaces.
We employ ultra-soft pseudopotentials and plane wave basis sets within the
generalized gradient approximation. The surface relaxations are found to be
small for both B- and Mg-terminated surfaces. For the B-terminated surface,
both B and surface bands appear, while only one B
surface band exists near the Fermi level for the Mg-terminated surface. The
superconductivity of the MgB surfaces is discussed. The work function is
predicted to be 5.95 and 4.25 eV for the B- and Mg-terminated surfaces
respectively. The simulated scanning tunneling microscopy images of the
surfaces are not sensitive to the sign and value of the bias voltages, but
depend strongly on the tip-sample distance. An image reversal is predicted for
the Mg-terminated surface.Comment: 3 pages, 4 figures, Revte
A First-principles Prediction of Two-Dimensional Superconductivity in Pristine B2C Single layer
Based on first-principles lattice dynamics and electron-phonon coupling
calculations, B2C sheet is predicted to be a two-dimensional (2D)
phonon-mediated superconductor with a relatively high transition temperature
(Tc). The electron-phonon coupling parameter calculated is 0.92, and it is
mainly contributed by low frequency out-of-plane phonon modes and electronic
states with a {\pi} character. When the Coulomb pseudopotential is set to 0.10,
the estimated temperature Tc is 19.2 K. To be best of our knowledge, B2C is the
first pristine 2D superconductor with a Tc higher than the boiling point of
liquid helium.Comment: accepted by Nanoscal
Increased interleukin-9 and Th9 cells in patients with refractory Graves’ disease and interleukin-9 polymorphisms are associated with autoimmune thyroid diseases
IntroductionAutoimmune thyroid diseases (AITDs) are prevalent disorders, primarily encompassing Graves’ disease (GD) and Hashimoto’s thyroiditis (HT). Despite their common occurrence, the etiology of AITDs remains elusive. Th9 cells, a new subset of CD4+T cells with immunomodulatory properties, have been linked to the development of various autoimmune diseases. However, research on the role of Th9 cells in AITDs is limited. MethodsWe investigated the expression of Th9 cells,their functional cytokine IL-9, and transcription factor IRF4 in peripheral blood mononuclear cells (PBMCs) and plasma of AITD patients and healthy controls. Additionally, we explored the genetic association between four loci polymorphisms (rs31564, rs2069879, rs1859430, and rs2069868) of the IL-9 gene and AITDs.ResultsWe reported, for the first time, that refractory GD patients exhibited elevated mRNA levels of IL-9 and IRF4 in PBMCs, increased IL-9 protein levels in plasma, and a higher proportion of Th9 cells in peripheral blood when compared to normal controls. Furthermore, human recombinant IL-9 protein was found to enhance IFN-g secretion in PBMCs from both GD patients and normal controls. At the genetic association level, after adjusting for age and sex, the rs2069879 polymorphism exhibited a significant association with AITDs under an additive model (P<0.001, OR= 0.05, 95% CI=0.03-0.08).DiscussionOur results reveal that Th9 cells may exert a pivotal role in the pathogenesis and progression of refractory GD and HT, and IL-9 holds promise as a novel therapeutic target for the management of AITDs
The Classification of Obesity Based on Metabolic Status Redefines the Readmission of Non-Hodgkin’s Lymphoma-An Observational Study
BACKGROUND: The relationship between obesity and non-Hodgkin\u27s lymphoma (NHL) was controversial, which may be due to the crudeness definition of obesity based on body mass index (BMI). As obesity and metabolic abnormalities often coexist, we aimed to explore whether the classification of obesity based on metabolic status can help to evaluate the real impact of obesity on the readmission of NHL.
METHODS: In this retrospective cohort study, utilizing the 2018 Nationwide Readmissions Database, we identified NHL-related index hospitalizations and followed them for non-elective readmission. The patients with NHL were classified as metabolically healthy non-obese (MHNO) and obese (MHO) and metabolically unhealthy non-obese (MUNO) and obese (MUO). Readmission rates for each phenotype were calculated at 30-day intervals. Multiple COX regression was used to analyze the association of metabolic-defined obesity with 30-day, 90-day, and 180-day readmission rates in patients with NHL.
RESULTS: There were 22,086 index hospitalizations with NHL included. In the multivariate COX regression, MUNO was associated with increased 30-day (HR = 1.113, 95% CI 1.036-1.195), 90-day (HR = 1.148, 95% CI 1.087-1.213), and 180-day readmission rates (HR = 1.132, 95% CI 1.077-1.189), and MUO was associated with increased 30-day (HR=1.219, 95% CI: 1.081-1.374), 90-day (HR = 1.228, 95% CI 1.118-1.348), and 180-day readmission rates (HR = 1.223, 95% CI 1.124-1.33), while MHO had no associations with readmission rates.
CONCLUSIONS: The presence of metabolic abnormalities with or without obesity increased the risk of non-selective readmission in patients with NHL. However, obesity alone had no associations with the risk of non-selective readmission, suggesting that interventions for metabolic abnormalities may be more important in reducing readmissions of NHL patients
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