Anomalous Josephson effect between d-wave superconductors through a two-dimensional electron gas with both Rashba spin-orbit coupling and Zeeman splitting

Based on the Bogoliubov-de Gennes equation and the extended McMillan’s Green’s function formalism,we study theoretically the Josephson effect between two d-wave superconductors bridged by a ballistic two-dimensional electron gas with both Rashba spin-orbit coupling and Zeeman splitting.We show that due to the interplay of Rashba spin-orbit coupling and Zeeman splitting and d-wave pairing,the current-phase relation in such a heterostructure may exhibit a series of novel features and can change significantly as some relevant parameters are tuned.In particular,anomalous Josephson current may occur at zero phase bias under various different situations if both time reversal symmetry and inversion symmetry of the system are simultaneously broken,which can be realized by tuning some relevant parameters of the system,including the relative orientations and the strengths of the Zeeman field and the spin-orbit field in the bridge region,the relative orientations of the a axes in two superconductor leads,or the relative orientations between the Zeeman field in the bridge region and the a axes in the superconductor leads.We show that both the magnitude and the direction of the anomalous Josephson current may depend sensitively on these relevant parameters.

Zeeman effects on Josephson current in d-wave superconductor/d-wave superconductor junctions

This paper solves a self-consistent equation for the d-wave superconducting gap and the effective exchange field in the mean-field approximation, and studies the Zeeman effects on the d-wave superconducting gap and thermodynamic potential. The Josephson currents in the d-wave superconductor（S）/insulating layer（I）/d-wave S junctions are calculated as a function of the temperature, exchange field, and insulating barrier strength under a Zeeman magnetic field on the two d-wave Ss. It is found that the Josephson critical currents in d-wave S/d-wave S junction to a great extent depend on the relative orientation of the effective exchange field of the two S electrodes, and the crystal orientation of the d-wave S. The exchange field under certain conditions can enhance the Josephson critical current in a d-wave S/I/d-wave S junction.

Unconventional chiral d-wave superconducting state in strained graphene

We consider a highly unconventional superconducting state with chiral d-wave symmetry in doped graphene under strain with the Gutzwiller–RVB method in the momentum space. It is shown that flat bands emerge in the normal state for reasonable strain. As a result, the superconducting critical temperature is found to be linearly proportional to the strength of the electron–electron interaction. Furthermore, the chiral d-wave superconducting state is shown with coexistence of the charge density wave and the pair density wave. There are different coexisting states with those orders under different doping levels.

Differential conductance in a normal metal/insulator/metal/d-wave superconductor junction carrying a supercurrent

This paper applies the Bogoliubov-de Gennes equation and the Blonder-Tinkham-Klapwijk approach to study the oscillatory behaviour of differential conductance in a normal metal/insulator/metal/d-wave superconductor junction carrying a supercurrent Is. We find that （i） a three-humped structure appears at a nearly critical supercurrent Is and z ≈ 0.5 for the normal metal/insulator/metal/dx^2＋y^2-wave superconductor junction; （ii） the zero-bias conductance peak splits into two peaks with sufficiently large applied current for the normal metal/insulator/metal/dxy-wave superconductor junction; （iii） the conductance spectrum exhibits oscillating behaviour with the bias voltage and the peaks of the resonances are suppressed by increasing supercurrent Is.

Superfluid phases and excitations in a cold gas of d-wave interacting bosonic atoms and molecules

Motivated by recent advances in orbitally tuned Feshbach resonance experiments, we analyze the ground-state phase diagram and related low-energy excitation spectra of a d-wave interacting Bose gas. A two-channel model with d-wave symmetric interactions and background s-wave interactions is adopted to characterize the gas. The ground state is found to have three interesting superfluid phases: atomic, molecular, and atomic–molecular. In great contrast to what was previously known about the p-wave case, the atomic superfluid is found to be momentum-independent for the d-wave case discussed here. The Bogoliubov spectra above each superfluid phase are obtained both analytically and numerically.

A New Approach to the Ground State of Superfluid Fermi Gas near the Feshbach Resonance of d-Wave

The following article has been retracted due to the investigation of complaints received against it. Mr. Mohammadali Ghorbani (corresponding author and also the last author) cheated the author’s name: Alireza Heidari. The scientific community takes a very strong view on this matter and we treat all unethical behavior such as plagiarism seriously. This paper published in Vol.3 No.2, 151-154, 2012, has been removed from this site.

Josephson Current in Superconductor-Ferromagnet／Insulator／d-Wave Superconductor Junctions

Solving the Bogoliubov-de Gennes equation, the energy levels of bound states are obtained in the ferromagnetic superconductor. The Josephson currents in a ferromagnetic superconductor/Insulator/d-wave superconductor junction are calculated as a function of the exchange field, temperature, and insulating barrier strength. It is found that the Josephson critical current is always suppressed by the presence of exchange field h and depends on crystalline axis orientation of d-wave superconductor.

Tunneling Conductance in Quantum-Wire/Ferromagnetic-Insulator/d-Wave Superconductor Junction

我们在更金色的 Tinkham Klapwijk 模型的框架在量电线 /ferromagnetic-insulator/d 波浪超导体连接(q/FI/d ) 学习了伪粒子运输。我们基于 Bogoliubov-de Gennes 方程在零温度和有限温度作为偏爱电压的功能在 q/FI/d 计算通道传导力。与在 normal-metal/insulator/d 波浪超导体连接的盒子不同，零偏爱的传导力山峰为单个模式的盒子消失。通道传导力系列取决于交换相互作用的大小在铁磁性绝缘体。

Quest towards “factoring larger integers with commercial D-Wave quantum annealing machines”

Integer factorization (IFP), also called prime factorization, is an important problem in number theory, cryptography, and quantum computation. Factoring large integers to attack the RSA cryptosystem is intractable for powerful supercomputers, let alone classical computers. In 1994, Shor [1]presented an algorithm that potentially enabled a quantum computer to find prime factors in polynomial time.

FINITE ELEMENT METHODS FOR A BI-WAVE EQUATION MODELING D-WAVE SUPERCONDUCTORS

In this paper we develop two conforming finite element methods for a fourth order bi-wave equation arising as a simplified Ginzburg-Landau-type model for d-wave superconductors in absence of applied magnetic field. Unlike the biharmonic operator A2, the bi-wave operator □^2 is not an elliptic operator, so the energy space for the bi-wave equation is much larger than the energy space for the biharmonic equation. This then makes it possible to construct low order conforming finite elements for the bi-wave equation. However, the existence and construction of such finite elements strongly depends on the mesh. In the paper, we first characterize mesh conditions which allow and not allow construction of low order conforming finite elements for approximating the bi-wave equation. We then construct a cubic and a quartic conforming finite element. It is proved that both elements have the desired approximation properties, and give optimal order error estimates in the energy norm, suboptimal （and optimal in some cases） order error estimates in the H1 and L^2 norm. Finally, numerical experiments are presented to guage the efficiency of the proposed finite element methods and to validate the theoretical error bounds.

D-Wave量子计算机,到底能不能进行量子计算

最近Google宣布在量子计算领域取得了突破性进展,他们用D-Wave量子计算机（图1）在解决某些问题上比传统计算机过程快了1亿倍。果真这样,它将带来人工智能技术的巨大进步。不过,有专家对此表示质疑,认为这些说法夸大其词了。那么Google所谓的D-Wave量子计算机,到底能不能做量子计算,这1亿倍的加速又是怎么回事？

三维TTI介质qP波透射立体层析方法研究

致力于研究三维TTI介质下的qP波立体层析反演算法.将射线扰动理论应用于三维具有倾斜对称轴的横向各向同性(TTI)介质拟声波程函方程,导出立体层析所需的三维TTI介质qP波数据空间与三维TTI介质模型空间之间的所有Frechét导数.在通过灵敏度测试验证了相应Frechét导数对于三个各向异性THOMSEN参数的正确性之后,使用两步法反演策略——即先使用坐标分量和射线参数水平分量(不包括走时)实施初始反演而后再使用所有数据空间分量进行反演,在三维qP波TTI介质情形下针对三个各向异性THOMSEN参数可以获得理想的反演结果,为三维qP波TTI介质下透射立体层析的应用做好了理论准备.用一个典型的理论数据算例证实了上述观点.

Zeeman effects on d-wave superconductor and tunneling spectrum in normal-metal/d-wave superconductor tunnel junction

We study the Zeeman effect on the d-wave superconductor and tunneling spectrum in normal-metal(N)/d-wave superconductor(S) junction by applying a Zeeman magnetic field to the S. It is shown that: (1) the Zeeman magnetic field can lead to the S gap decreasing, and with the increase in Zeeman energy, the superconducting state is changed to the normal state, exhibiting a first-order phase transition; (2) the Zeeman magnetic field may make the zero-bias conductance peak split into two peaks, and the energy difference between the two splitting peaks in the conductance spectrum is equal to 2h0 (h0 is the Zeeman energy); (3) both the barrier strength of interface scattering and the temperature can lower the magnitudes of splitting peaks, of which the barrier strength can lead to the splitting peaks becoming sharp and the temperature can smear out the peaks, however, neither of them can influence the Zeeman effect.

Effects of dopamine D_(1) receptor blockade on the ERG b- and d-waves during blockade of ionotropic GABA receptors

Background:Some data indicate that the dopaminergic and GABAergic systems interact in the vertebrate retina,but the type of interactions is not well understood.Methods:In this study we investigated the effect of dopamine D_(1) receptor blockade by 75μM SCH 23390 on the electroretinographic ON(b-wave)and OFF(d-wave)responses in intact frog eyecup preparations and in eyecups where the ionotropic GABA receptors were blocked by 50μM picrotoxin.Student’s t-test,One-way repeated measures ANOVA with Bonferroni post-hoc test and Two-way ANOVA were used for statistical evaluation of the data.Results:We found that SCH 23390 alone significantly enhanced the amplitude of the b-and d-waves without altering their latency.The effect developed rapidly and was fully expressed within 8-11 min after the blocker application.Picrotoxin alone also markedly enhanced the amplitude of the ERG ON and OFF responses and increased their latency significantly.The effect was fully expressed within 25-27 min after picrotoxin application and remained very stable in the next 20 min.The effects of SCH 23390 and picrotoxin are similar to that reported in our previous studies.When SCH 23390 was applied on the background of the fully developed picrotoxin effect,it diminished the amplitude of the b-and d-waves in comparison to the corresponding values obtained during application of picrotoxin alone.Conclusion:Our results demonstrate that the enhancing effect of D_(1) receptor blockade on the amplitude of the ERG b-and d-waves is not evident during the ionotropic GABA receptor blockade,indicating an interaction between these neurotransmitter systems in the frog retina.We propose that the inhibitory effect of endogenous dopamine mediated by D_(1) receptors on the ERG ON and OFF responses in the frog retina may be due to the dopamine-evoked GABA release.

Disorder driven superconductor-insulator transition in inhomogenous d-wave superconductor

We study the effect of disorder on the superconductor-insulator transition in an inhomogeneous d-wave superconductor using the kernel polynomial method. As the Bogoliubov-de Gennes equations of the two-dimensional square lattice are solved self-consistently for the cases with more than 100000 unit cells, it is possible to observe the spatial fluctuations of the superconducting order parameters at the nanoscale. We find that strong spatial fluctuation of the superconducting order parameters can be introduced by disorder, and some superconducting specific order parameters are even enhanced. Moreover, we find that some isolated superconducting "islands" can survive the strong disorder, giving a boson insulator with some localized Cooper pairs. Our numerical calculations predict the existence of two sequential transitions with the increasing disorder strength: a d-wave to s-wave superconductor transition, and then an s-wave superconductor to insulator transition. The possibility of the appearance of a metallic phase between the superconducting and insulating phases is excluded by performing the lattice-size scaling of the generalized inverse participation ratio. In addition, we also discuss the effect of disorder on the optical conductivity of the d-wave superconductors.

基于单频走时敏感度核函数的三维波动方程初至层析

地震波走时层析是主要的近地表速度建模技术.对于变速模型,尤其是复杂近地表模型,波动方程能够更加精确地描述地震波的一阶绕射效应,理论上反演精度高于射线(束)类层析.然而,波动方程的数值求解的计算量较射线理论增加了几个数量级,严重制约了波动方程走时层析技术的三维实用化.为解决波动方程走时层析中遇到的计算和存储问题,本文通过引入随机边界条件以及离散Fourier积分,提出了基于单频梯度反演策略的实用化三维波动方程初至层析方法.本文方法的优势在于:在计算和存储方面,相比于基于波场重构算法(需要三次波传播)的梯度计算策略,本文提出的单频梯度计算方法对内存需求极低(相对于波动方程正演,仅需要增加两个单频波场以及一个成像体),且计算量至少减少1/3(仅需要两次波传播且无需处理数值吸收边界).此外,随机边界的引入使得正演算法大幅简化因而更适用于GPU(Graphics Processing Unit,图形处理器)加速.在理论层面,由于影响地震波一阶散射效应的主要区域集中在连接炮检的中心射线邻域的第一菲涅尔带内,随机边界条件的引入降低了随机边界内产生的散射波的空间相关性,使得第一菲涅尔带内的单频梯度相干加强;同时,地震观测系统的多次覆盖特性有助于第一菲涅尔带外的高波数振荡相互干涉.数值实验表明,光滑处理后的单频梯度仍然保留了非常可观的低波数成分,有助于实现背景速度反演.此外,三维复杂模型反演结果验证了本文方法能够较为准确地反演近地表速度结构.相对于传统的波动方程走时层析实现方案,本文方法在显著降低内存需求的同时进一步提高了计算效率,有望将波动方程初至层析技术推向三维实用化.

Effects of T-Factor on Quantum Annealing Algorithms for Integer Factoring Problem

The hardness of the integer factoring problem(IFP)plays a core role in the security of RSA-like cryptosystems that are widely used today.Besides Shor’s quantum algorithm that can solve IFP within polynomial time,quantum annealing algorithms(QAA)also manifest certain advantages in factoring integers.In experimental aspects,the reported integers that were successfully factored by using the D-wave QAA platform are much larger than those being factored by using Shor-like quantum algorithms.In this paper,we report some interesting observations about the effects of QAA for solving IFP.More specifically,we introduce a metric,called T-factor that measures the density of occupied qubits to some extent when conducting IFP tasks by using D-wave.We find that T-factor has obvious effects on annealing times for IFP:The larger of T-factor,the quicker of annealing speed.The explanation of this phenomenon is also given.

2013年辽宁灯塔M5.1地震前小震序列震源机制一致性特征

从辽宁测震台网2012年1月1日至2022年7月10日的观测报告中筛选出36049条Pg震相走时数据,反演了辽宁地区最小一维P波速度模型。采用P波初动方法求解了2012年1月1日至2013年1月23日灯塔M 5.1地震发生前,震中附近M_(L)2.5~4.1地震震源机制解,并根据三角形图解分类方法进行了分类。计算了这些小震与灯塔M 5.1地震震源机制解的最小空间旋转角,通过分析其变化趋势,发现灯塔M 5.1地震前小震序列存在明显的震源机制一致性特征。

2019年长宁M_(s)6.0地震周边区域速度与P波各向异性成像研究

利用基于程函方程求解的地震走时层析成像方法对2019年长宁M_(s)6.0地震震中及其周边区域进行反演成像,获得了该区域高分辨率三维P波、S波速度结构以及P波方位角各向异性参数分布,并对几个典型剖面的泊松比结构进行了分析。结果表明,方位角各向异性对地震波P波走时具有显著的影响;研究区域上地壳速度结构存在显著的非均匀性,且一些相对低速异常与注水采盐、天然气水力压裂开采及废水回注等工业活动区域具有明显的对应关系,显示人类的工业活动可能已经对上地壳的物质性质产生了影响。长宁地震的发生可能由注水采盐活动直接诱发,而由工业活动所造成的速度异常结构对区域内地震的发生可能产生的影响是持续性的。区域内P波方位角各向异性可能受板块运动和主压应力影响,而长宁地震序列震源区域浅层P波方位角各向异性以近EW向为主,与该区域的主压应力方向基本一致。这些结果为认识四川盆地东南缘精细地壳结构、深部物质运动和动力学机制提供了新的资料。

剪切波弹性成像及双功能超声联合血浆D-二聚体预测急性期孤立性远端深静脉血栓患者发生肺动脉栓塞的风险

目的 利用实时剪切波弹性成像(SWE)、双功能超声(DUS)联合血浆D-二聚体评估急性期孤立性远端深静脉血栓(IDDVT)患者发生肺动脉栓塞(PE)的风险。方法 回顾性分析2021年1月至2022年10月在云南大学附属医院行下肢血管超声检查的IDDVT患者的临床资料。CTPA阳性患者作为PE组(n=46),CTPA阴性患者作为对照组(n=47)。对比两组患者的血栓超声测值、剪切波杨氏模量值及D-二聚体等多项指标,多因素分析筛选出肺动脉栓塞的预测因素,并构建可视化Nomogram。结果 多因素logistic回归分析显示,血浆D-二聚体(OR=1.370,95%CI:1.101~1.705),血栓宽度最大值(OR=1.892,95%CI:1.357~2.639),杨氏模量均值(OR=0.806,95%CI:0.680~0.954)是IDDVT患者发生PE的预测因素。筛选变量后构建的Nomogram可直观显示IDDVT后发生PE的风险,预测值与真实值之间符合度的平均绝对误差为0.032。在单项指标的分析中,血栓宽度最大值的曲线下面积(AUC)为0.760(95%CI:0.665~0.855),杨氏模量平均值的AUC为0.635(95%CI:0.522~0.748),D-二聚体的AUC为0.740(95%CI:0.641~0.839)。三者联合预测PE的AUC为0.851(95%CI:0.775~0.927)。经DeLong检验,预测模型AUC与血栓宽度最大值、血栓杨氏模量平均值、D-二聚体比较显著提高(P=0.021、0.001、0.011)。结论 SWE、DUS联合血浆D-二聚体在预测急性期IDDVT患者发生PE的风险方面具有潜在的临床价值。该方法可以帮助临床医师对患者进行风险分层,并指导进一步的管理决策。