Slow Light of an Amplitude Modulated Gaussian Pulse in Cesium Vapor

Slow light of an amplitude modulated Gaussian (AMG) pulse in cesium vapor is demonstrated and studied, as an appropriate amplitude modulation to a single pulse can expand its spectrum and thus increase the utilization efficiency of the bandwidth of a slow light system. In a single-$\Lambda$ type electromagnetically induced transparency (EIT) system, the slowed AMG pulse experiences severe distortion, mainly owing to the frequency dependent transmission of medium. Additionally, due to its spectral distribution, the frequency dependent dispersion of the medium causes simultaneous slow and fast light of different spectral components and thus a certain dispersive distortion of the AMG pulse. Further, a post-processing method is proposed to recover the slowed (distorted) pulse, which indicates that by introducing a linear optical system with a desired gain spectrum we can recover the pulse in an "all-optical" way. Finally, we discuss the limitations during this compensation procedure in detail. Although it is demonstrated in the cesium vapor using EIT, this method should be applicable to a wide range of slow light systems.Comment: 5 pages, 5 figure

DDCoT: Duty-Distinct Chain-of-Thought Prompting for Multimodal Reasoning in Language Models

A long-standing goal of AI systems is to perform complex multimodal reasoning like humans. Recently, large language models (LLMs) have made remarkable strides in such multi-step reasoning on the language modality solely by leveraging the chain of thought (CoT) to mimic human thinking. However, the transfer of these advancements to multimodal contexts introduces heightened challenges, including but not limited to the impractical need for labor-intensive annotation and the limitations in terms of flexibility, generalizability, and explainability. To evoke CoT reasoning in multimodality, this work first conducts an in-depth analysis of these challenges posed by multimodality and presents two key insights: "keeping critical thinking" and "letting everyone do their jobs" in multimodal CoT reasoning. Furthermore, this study proposes a novel DDCoT prompting that maintains a critical attitude through negative-space prompting and incorporates multimodality into reasoning by first dividing the reasoning responsibility of LLMs into reasoning and recognition and then integrating the visual recognition capability of visual models into the joint reasoning process. The rationales generated by DDCoT not only improve the reasoning abilities of both large and small language models in zero-shot prompting and fine-tuning learning, significantly outperforming state-of-the-art methods but also exhibit impressive generalizability and explainability.Comment: 24 pages, 13 figures, to be published in NeurIPS 202

Phase transition and hysteresis in scale-free network traffic

We model information traffic on scale-free networks by introducing the node queue length L proportional to the node degree and its delivering ability C proportional to L. The simulation gives the overall capacity of the traffic system, which is quantified by a phase transition from free flow to congestion. It is found that the maximal capacity of the system results from the case of the local routing coefficient \phi slightly larger than zero, and we provide an analysis for the optimal value of \phi. In addition, we report for the first time the fundamental diagram of flow against density, in which hysteresis is found, and thus we can classify the traffic flow with four states: free flow, saturated flow, bistable, and jammed.Comment: 5 pages, 4 figure

ROC Analysis for Phase II Group Sequential Basket Clinical Trial

The basket trial is a recent development in the clinical trial practice. It conducts the test of the same treatment on several different related diseases in a single trial, and has the advantage of reduced cost and enhanced efficiency. A natural question is how to assess the performance of the group sequential basket trial against the classical group sequential trial? To our knowledge, a formal assessment hasn't been seen in the literature, and is the goal of this study. Specifically, we use the receiver operating characteristic curve to assess the performance of the mentioned two trials. We considered two cases, parametric and nonparametric settings. The former is efficient when the parametric model is correctly specified, but can bemis-leading if the model is incorrect; the latter is less efficient but is robust in that it cannot be wrong no matter what the true data generating model is. Simulation studies are conducted to evaluate the experiments, and it suggests that the group sequential basket trial generally outperforms the group sequential trial in either the parametric and nonparametric cases, and that the nonparametric method gives more accurate evaluation than the parametric one for moderate to large sample sizes

Tetra­kis(μ-2,4-difluoro­benzoato)bis­[(2,4-difluoro­benzoato)(1,10-phenanthroline)gadolinium(III)]

In the title compound, [Gd2(C7H3F2O2)6(C12H8N2)2], the asymmetric unit comprises one Gd3+ cation chelated by two 2,4-difluoro­benzoate and one 1,10-phenanthroline ligands. Two cations are linked into a centrosymmetric dimer via three bridging carboxyl­ate groups of 2,4-difluoro­benzoate ligands. Each Gd3+ ion is nine-coordinated by seven O atoms and two N atoms

Current reversals and metastable states in the infinite Bose-Hubbard chain with local particle loss

We present an algorithm which combines the quantum trajectory approach to open quantum systems with a density-matrix renormalization group scheme for infinite one-dimensional lattice systems. We apply this method to investigate the long-time dynamics in the Bose-Hubbard model with local particle loss starting from a Mott-insulating initial state with one boson per site. While the short-time dynamics can be described even quantitatively by an equation of motion (EOM) approach at the mean-field level, many-body interactions lead to unexpected effects at intermediate and long times: local particle currents far away from the dissipative site start to reverse direction ultimately leading to a metastable state with a total particle current pointing away from the lossy site. An alternative EOM approach based on an effective fermion model shows that the reversal of currents can be understood qualitatively by the creation of holon-doublon pairs at the edge of the region of reduced particle density. The doublons are then able to escape while the holes move towards the dissipative site, a process reminiscent---in a loose sense---of Hawking radiation