Superconducting gap ratio from strange metal phase in the absence of quasiparticles

A lttice model for strongly interacting electrons motivated by a rank-3 tensor model provides a tool for understanding the pairing mechanism of high-temperature superconductivity.This Sachdev Ye Kitaev-like model describes the strange metal phase in the cuprate high temperature superconductors.Our calculation indicates that the superconducting gap ratio in this model is higher than the ratio in the BCS theory due to the coupling term and the spin operator.Under certain conditions,the ratio also agrees with the BCS theory.Our results relate to the case of strong coupling,so it may pave the way to gaining insight into the cuprate high temperature superconductors.     

液晶中一种稳定的相态:蓝相

文章描述了胆甾相液晶中蓝相的研究现况．蓝相(BP)是液晶中具有特殊性质的一个相态，它的序参量表现出三维空间周期性．蓝相是出现在一个狭小的温度间隔里(量级为0．1—1K)的稳定相态．文章对已观察到的BPⅠ，BPⅡ，BPⅢ(“雾”相)的性质做了简要的叙述．对研究液晶蓝相的主要理论——Ginzburg-Landau理论(唯象理论)作了介绍，并指出了蓝相研究的实际物理意义。     

凝聚态物理与量子力学

文章扼要地回顾了量子力学在奠定凝聚态物理基础中所起的关键作用;并讨论了当今凝聚态物理发展的主要动向;进而阐明了为何凝聚态物理,不论在基础研究,还是促进技术发展,抑或推动学科交叉方面,尚大有可为。     

一些典型的软物质物理中的非平衡自组织现象

在软物质物理中经常有自组织(self-organization)现象发生.这一现象通常在非平衡的过程中产生,并生成非常美丽和有趣的图案与结构.具体例子包括胶体颗粒的扩散限制凝聚(diffusion limited aggregation,DLA),Hele-Shaw盒中产生的流体分形结构,凝胶的形成(gelation),生物体自组织聚集,以及颗粒类物质(granular material)运动产生的规则图案等.这些现象在软物质物理研究中产生了很多重要结果.文章以比较浅显的文字介绍这些软物质物理中的非平衡自组织现象.     

Density functional theory for chiral nematic liquid crystals

ABSTRACT

In this note, the density functional theory for chiral nematic liquid crystals is expressed in terms of rotational invariant expansion coefficients of the pair-excluded area at fixed separation. This modification from the standard approach, without making any additional assumptions, yields a more efficient procedure for minimising the free energy, as well as providing insight into the origins of the effect away from the long-pitch limit.     

All basic condensed matter physics phenomena and notions mirror in biology — A hypothesis,two examples and a novel prediction

A few billion years of evolutionary time and the complex process of ‘selection’ has given biology an opportunity to explore a variety of condensed matter phenomena and situations, some of which have been discovered by humans in the laboratory, that too only in extreme non-biological conditions such as low temperatures, high purity, high pressure etc., in the last centuries. Biology, at some level, is a complex and self-regulated condensed matter system compared to the ‘inanimate’ condensed matter systems such as liquid ⁴He, liquid water or a piece of graphite. In this article I propose a hypothesis that ‘all basic condensed matter physics phenomena and notions (already known and ones yet to be discovered) mirror in biology’. I explain this hypothesis by considering the idea of ‘Bose condensation’ or ‘momentum space order’ and discuss two known example of quantum magnetism encountered in biology. I also provide some new and rather speculative possibility, from light harvesting in biological photosynthesis, of mesoscopic excition condensation related phenomena at room temperature.     

Did Günter Nimtz discover tachyons?

It is argued that in the famous G. Nimtz experiment tachyons were produced and annihilated. We base our considerations on the new version of Special Relativity elaborated recently by one of the authors.     

凝聚态物理学与材料研究的前沿问题

讨论了凝聚态物理学在当代材料研究的前沿问题中所起的作用，首先对，于那些基本物理学业已能晓的常规材料，极好的机会在于设计并制备出微结构和纳米结构，其次，对于具有强关联电子特征的复杂材料，虽则其物理学尚在探索之中，已有迹象表明这将是新材料的“富矿区”，再次，关于有机及聚合物材料，物理学正在向这领域延拓，在设计和制备分子和超分子结构方面，将会提供许多新的可能性。     

软物质的自组织

软物质的基本特征使得软特在各种互作用竞争，外力和熵驱动下显示出丰富的自组织现象，本文系统地评述了典型软物质系统各种丰富的自组织现象，试图从丰富的自组织现象中寻找共同规律和竞争机理，来揭示和探索自组装／自组织有序微结构形成的物理机制和动力学引起的新生长规律，并讨论如何来控制和设计自组装／自组织有序结构，这对新材料的制备，新结构的实现具有十分重要的科学意义和实际应用价值。     

软物质的自组织

软物质的基本特征使得软物质在各种互作用竞争 ,外力和熵驱动下显示出丰富的自组织现象。本文系统地评述了典型软物质系统各种丰富的自组织现象 ,试图从丰富的自组织现象中寻找共同规律和竞争机理 ,来揭示和探索自组装 /自组织有序微结构形成的物理机制和动力学引起的新生长规律 ,并讨论如何来控制和设计自组装 /自组织有序结构。这对新材料的制备、新结构的实现具有十分重要的科学意义和实际应用价值。     

Orientational Order Parameters for Arbitrary Quantum Systems

The concept of quantum-mechanical nematic order, which is important in systems such as superconductors, is based on an analogy to classical liquid crystals, where order parameters are obtained through orientational expansions. This method is generalized to quantum mechanics based on an expansion of Wigner functions. This provides a unified framework applicable to arbitrary quantum systems. The formalism recovers the standard definitions for spin systems. For Fermi liquids, the formalism reveals the nonequivalence of various definitions of the order parameter used in the literature. Moreover, new order parameters for quantum molecular systems with low symmetry are derived, which cannot be properly described with the usual nematic tensors.     

Bichromatic coherent random lasing from dye-doped polymer stabilized blue phase liquid crystals controlled by pump light polarization

In this paper, we investigate the bichromatic coherent random lasing actions from the dye-doped polymer stabilized blue phase liquid crystals. Two groups of lasing peaks, of which the full widith at half maximum is about 0.3 nm, are clearly observed. The shorter- and longer-wavelength modes are associated with the excitation of the single laser dye (DCM) monomers and dimers respectively. The experimental results show that the competition between the two groups of the lasing peaks can be controlled by varying the polarization of the pump light. When the polarization of the pump light is rotated from 0° to 90°, the intensity of the shorter-wavelength lasing peak group reduces while the intensity of the longer-wavelength lasing peak group increases. In addition, a red shift of the longer-wavelength modes is also observed and the physical mechanisms behind the red-shift phenomenon are discussed.     

Mildred Dresselhaus and Solid State Pedagogy at MIT

Mildred Dresselhaus is known for her influential research on the physics of carbon. Her wide‐ranging influence as a physics teacher, although well‐known to her students, has been less thoroughly examined. Exploring how Dresselhaus grew into her role teaching solid state physics at MIT reveals much about how that subfield evolved.     

从液晶显示到液晶生物膜理论：软凝聚态物理在交叉学科发展中的创新机遇

世界之交,物理学正在与化学、材料科学、生命科学等相互交叉形成新的学科,凝聚态物理为例,在传统的固体物理以外,最近几年又诞生了一门新学科－－软件体物理、或称为复杂流体,液晶 物质凝聚态的重要研究对象,６０年代发展起来的液晶显示技术与７０年代创立的液晶生物膜理论,充分显示了软凝聚态物理在２１世纪的信息与生命科学时代将发挥重要的基础学科作用,是科学技术富于创新发展的领域。     

无尽的探索——写在超导电性发现100周年

在凝聚态物理领域,没有一门学科像超导电性一样,历尽百年坎坷,却依然生机勃勃,吸引着科学家及大众的探索热情.本文简要叙述了超导电性发现100年来的重要历史事件.从昂纳斯发现汞具有超导电性开始,到铌锗合金;从高温超导电性的发现到二硼化镁,铁砷超导体;从BCS微观理论到目前的理论混乱状态.超导电性的历史就是一幅跌宕起伏和蕴含...     

La2CuO4型超导体中电荷有序行为的超声衰减特性研究

本文系统研究了La2CuO4型超导体中电荷有序行为相关的超声衰减特性。在La1．88-y，NdySr0．12CuO4系列样品中观察到由于动态及静态的电荷条纹与晶格之间耦合而导致的超声声速和衰减异常。不同磁场下La1.88Sr0.12-xBaxCuO4系列样品的超声衰减特性表明x≤0．04的样品中存在局域的电荷条纹有序，外加磁场压制超导电性后能够导致局域电荷条纹序的增强。实验结果表明电声子相互作用在铜氧化物超导体的电荷有序现象中扮演着重要的角色。     

缪子源及多学科研究和应用

缪子作为粒子物理标准模型中基本粒子中的一种,因其易产生且性质独特,常被用来作为探针开展从粒子物理研究到基于一种所谓μSR (缪子自旋共振、旋转和弛豫的缩写) 技术的多学科研究平台、再到缪束技术的应用等不同领域的科学研究,因此,高性能的缪子源是国际上综合性科学研究的重要实验平台。文章介绍缪子的基本性质、缪子束流的产生、主要应用领域、国际缪子源发展现状和趋势、特别是我国缪子源及缪子科学的发展潜力。随着中国散裂中子源实验缪子源的即将建设,我国缪子科学必将迎来一个极大的发展机遇。     

活力物质的非平衡结构和动力学

活力物质是一类典型的非平衡态体系,已成为软凝聚态物理新近发展的一个重要研究方向.活力物质由微驱动粒子组成,驱动力独立地施加在体系中的每个粒子上.文章概述了作者平时研究中所关注的一些活力物质系统中出现的十分有意义的现象,着重介绍了活力物质系统的构成,以及活力物质的气液态、铁磁态、向列相态和凝胶状态中涌现出的非平衡结构及其特殊的动力学行为.