A quantum chain model of multiple molecule motors is proposed as a mathematical physics theory for the microscopic modeling of classical force-velocity relation and tension transients in muscle fibers. The proposed mo...A quantum chain model of multiple molecule motors is proposed as a mathematical physics theory for the microscopic modeling of classical force-velocity relation and tension transients in muscle fibers. The proposed model was a quantum many-particle Hamiltonian to predict the force-velocity relation for the slow release of muscle fibers, which has not yet been empirically defined and was much more complicated than the hyperbolic relationships. Using the same Hamiltonian model, a mathematical force-velocity relationship was proposed to explain the tension observed when the muscle was stimulated with an alternative electric current. The discrepancy between input electric frequency and the muscle oscillation frequency could be explained physically by the Doppler effect in this quantum chain model. Further more, quantum physics phenomena were applied to explore the tension time course of cardiac muscle and insect flight muscle. Most of the experimental tension transient curves were found to correspond to the theoretical output of quantum two- and three-level models. Mathematical modeling electric stimulus as photons exciting a quantum three-level particle reproduced most of the tension transient curves of water bug Lethocerus maximus.展开更多
We report on the theoretical and experimental investigations of the transition of a typical quantum system with mixed regular-integrable classical dynamics to one with violated time-reversal(T)invariance.The measureme...We report on the theoretical and experimental investigations of the transition of a typical quantum system with mixed regular-integrable classical dynamics to one with violated time-reversal(T)invariance.The measurements are performed with a flat superconducting microwave resonator with circular shape in which chaoticity is induced by using either long antennas or inserting two circular disks into the cavity,and by magnetizing a ferrite disk placed at its center,which leads to violation of T invariance.We propose an extension of the Rosenzweig-Porter(RP)model,which interpolates between mixed regular-chaotic instead of integrable dynamics and fully chaotic dynamics with violated T-invariance,and derive a Wigner-surmise like analytical expression for the corresponding nearest-neighbor spacing distribution.We propose a procedure involving this result and those for the RP model to determine the size of T-invariance violation and chaoticity and validate it employing the experimental eigenfrequency spectra.展开更多
Density downramp injection has been demonstrated to be an elegant and efficient approach for generating high-quality electron beams in laser wakefield accelerators.Recent studies have demonstrated the possibilities of...Density downramp injection has been demonstrated to be an elegant and efficient approach for generating high-quality electron beams in laser wakefield accelerators.Recent studies have demonstrated the possibilities of generating electron beams with charges ranging from tens to hundreds of picocoulombs while maintaining good beam quality.However,the plasma and laser parameters in these studies have been limited to specific ranges or attention has been focused on separate physical processes such as beam loading,which affects the uniformity of the accelerating field and thus the energy spread of the trapped electrons,the repulsive force from the rear spike of the bubble,which reduces the transverse momentum P⊥of the trapped electrons and results in small beam emittance,and the laser evolution when traveling in the plasma.In this work,we present a comprehensive numerical study of downramp injection in the laser wakefield,and we demonstrate that the current profile of the injected electron beam is directly correlated with the density transition parameters,which further affects the beam charge and energy evolution.By fine-tuning the plasma density parameters,electron beams with high charge(up to several hundreds of picocoulombs)and low energy spread(around 1%FWHM)can be obtained.All these results are supported by large-scale quasi-threedimensional particle-in-cell simulations.We anticipate that the electron beams with tunable beam properties generated using this approach will be suitable for a wide range of applications.展开更多
The tunneling current in a graphene nanoribbon tunnel field effect transistor(GNR-TFET) has been quantum mechanically modeled. The tunneling current in the GNR-TFET was compared based on calculations of the Dirac-like...The tunneling current in a graphene nanoribbon tunnel field effect transistor(GNR-TFET) has been quantum mechanically modeled. The tunneling current in the GNR-TFET was compared based on calculations of the Dirac-like equation and Schrodinger’s equation. To calculate the electron transmittance, a numerical approach-namely the transfer matrix method(TMM)-was employed and the Launder formula was used to compute the tunneling current. The results suggest that the tunneling currents that were calculated using both equations have similar characteristics for the same parameters, even though they have different values. The tunneling currents that were calculated by applying the Dirac-like equation were lower than those calculated using Schrodinger’s equation.展开更多
A steady state analysis of the nonclassical features and statistical properties of the cavity radiation of a two- photon coherent beat laser is presented. Results show that the degree of two-mode squeezing, detectable...A steady state analysis of the nonclassical features and statistical properties of the cavity radiation of a two- photon coherent beat laser is presented. Results show that the degree of two-mode squeezing, detectable entanglement and intensity of the cavity radiation can increase with the deviation of the phase fluctuations of the laser employed in preparing the atoms, but decrease with the increasing rate at which the induced coherence superposition decays. Although it is found that varying the phase fluctuations and dephasing can lead to modification in the quantum features and statistical properties of the radiation, it does not alter the similarity in the nature of the degree of entanglement detectable by the criteria following from Duan-Giedke-Cirac Zoller and logarithmic negativity in a perceivable manner. Since the intensity and quantum features can be readily enhanced, this system is expected to be a viable source of a strong robust entangled （squeezed） light under various conditions. Moreover, comparison of the mean number of photon pairs with intensity difference shows that the chance of inciting a two-photon process can be enhanced by changing the rate of dephasing and phase fluctuations.展开更多
This topical review article reports rapid progress on the generalization and application of entanglement in non-Hermitian free-fermion quantum systems.We begin by examining the realization of non-Hermitian quantum sys...This topical review article reports rapid progress on the generalization and application of entanglement in non-Hermitian free-fermion quantum systems.We begin by examining the realization of non-Hermitian quantum systems through the Lindblad master equation,alongside a review of typical non-Hermitian free-fermion systems that exhibit unique features.A pedagogical discussion is provided on the relationship between entanglement quantities and the correlation matrix in Hermitian systems.Building on this foundation,we focus on how entanglement concepts are extended to non-Hermitian systems from their Hermitian free-fermion counterparts,with a review of the general properties that emerge.Finally,we highlight various concrete studies,demonstrating that entanglement entropy remains a powerful diagnostic tool for characterizing non-Hermitian physics.The entanglement spectrum also reflects the topological characteristics of non-Hermitian topological systems,while unique non-Hermitian entanglement behaviors are also discussed.The review is concluded with several future directions.Through this review,we hope to provide a useful guide for researchers who are interested in entanglement in non-Hermitian quantum systems.展开更多
Modulational instability conditions for the generation of localized structures in the context of matter waves in Bose-Einstein condensates are investigated analytically and numerically. The model is based on a modifie...Modulational instability conditions for the generation of localized structures in the context of matter waves in Bose-Einstein condensates are investigated analytically and numerically. The model is based on a modified Gross-Pitaevskii equation, which account for the energy dependence of the two-body scattering amplitude. It is shown that the modified term due to the quantum fluctuations modify significantly the modulational instability gain. Direct numerical simulations of the full modified Gross-Pitaevskii equation are performed, and it is found that the modulated plane wave evolves into a train of pulses, which is destroyed at longer times due to the effects of quantum fluctuations.展开更多
Ionizing radiation (IR) is the most common treatment used to control localized primary prostate cancer (PC). However, for a significant number of patients, radiotherapy fails to adequately control the tumor. Thus, a m...Ionizing radiation (IR) is the most common treatment used to control localized primary prostate cancer (PC). However, for a significant number of patients, radiotherapy fails to adequately control the tumor. Thus, a main clinical problem today is the lack of a specific marker that may be used to predict the treatment outcome and to identify prostate cancer patients who are unlikely to respond to radiation therapy. In this study, we used human PC xenografts with predetermined radioresistant/sensitive phenotypes, and gene expression microarrays, correlated their specific transcripttional profiles with response to radiation. Employing unsupervised two-way hierarchical clustering, we identified four gene clusters displaying different expression patterns. Two clusters showed higher expression levels in the resistant xenografts and the other two clusters showed higher expression levels in the sensitive xenografts. Expression levels of 113 genes differed by at least 3 fold between sensitive and resistant xenografts. These genes represent members of several cellular pathways, some of which are known to be associated with response to radiation. All or several of these genes could serve as predictive tools to determine at biopsy the expected response of a particular tumor to radiotherapy. Indeed, the profiles we identified enabled us to predict the degree of radiosensitivity of a panel of established PC cell lines. Importantly, irradiation of the PC xenografts did not induce any significant changes in gene expression, regardless of their susceptibility phenotype. These data strongly support the first of two models: a: a random effect of irradiation on a homogeneous population of cells, rather than b: of a tumor comprised of a mixture of radioresistant and radiosensitive cell subpopulations. Our findings imply that each of the radio-phenotypes represents different intrinsic characteristics that affect the ability of a tumor to survive radiotherapy.展开更多
This study investigates the dromion structure within the context of(2+1)-dimensional modulated positron-acoustic waves in a magnetoplasma consisting of inertial cold positrons and inertialess nonthermal hot electrons ...This study investigates the dromion structure within the context of(2+1)-dimensional modulated positron-acoustic waves in a magnetoplasma consisting of inertial cold positrons and inertialess nonthermal hot electrons and positrons as well as stationary positive ions.The reductive perturbation approach reduces the fluid governing equations to the plasma model to a Davey–Stewartson system.This study provides a detailed analysis of the influence of many related plasma parameters,including the density ratio of hot and cold positrons,the external magnetic field strength,the nonthermal parameter and the density ratio of electrons and cold positrons,on the growing rate of instability.Using the Hirota Bilinear method,it is found that the system supports some exact solutions,such as one-and two-dromion solutions.The change of plasma parameters significantly enhances the characteristics of dromion solutions.The elastic and inelastic collisions between two dromions are discussed at different times.The relevance of this study can help us to understand the various types of collision between energetic particles in confined plasma during the production of energy by thermonuclear fusion.展开更多
The Fano line shape,arising from the interference of pathways for the excitation of discrete and continuum states,plays a fundamental role in many branches of physics,chemistry,and materials science.Exciting the reson...The Fano line shape,arising from the interference of pathways for the excitation of discrete and continuum states,plays a fundamental role in many branches of physics,chemistry,and materials science.Exciting the resonance with a high harmonic provides naturally a phase delay between the pathways leading to a complex asymmetry parameter.We demonstrate that its amplitude and phase can be controlled on the femtosecond and attosecond time scales,respectively.With our high-energy-resolution(10-meV)experiment,we dynamically image a resonance-enhanced electron wave packet during its temporal evolution,extracting both the amplitude and the phase.Calculations reproduce our experimental results.Our approach constitutes a method for measuring the photoionization delays of a resonance and enables the reconstruction of the electron wave packet in the time domain.This concept of an interferencecontrolled Fano line shape is a step toward attosecond quantum optics with potential ramifications into nanoscience and next-generation optical materials.展开更多
自旋是基本粒子(电子、光子)角动量的内在形式.固体中体现自旋特征的集体电子行为如拓扑绝缘体等是当前凝聚态物理领域关注的焦点,是基态行为.激子作为电子空穴对的激发态且寿命很短,可复合发光,它是否能体现自旋极化主导的行为?对此人...自旋是基本粒子(电子、光子)角动量的内在形式.固体中体现自旋特征的集体电子行为如拓扑绝缘体等是当前凝聚态物理领域关注的焦点,是基态行为.激子作为电子空穴对的激发态且寿命很短,可复合发光,它是否能体现自旋极化主导的行为?对此人们的认识远不如针对基态的电子.激子磁极化子(exciton magnetic polaron, EMP)是由磁性半导体微结构中铁磁自旋耦合态与自由激子相互作用形成的复合元激发,但其研究很有限.本文概述了我们在稀磁半导体微纳米结构中的EMP及其发光动态学光谱、自旋极化激子凝聚态的形成方面取得的一些进展,展望了未来可能在自旋光电子器件、磁控激光、光致磁性等量子技术方面的潜在应用.展开更多
We present the joint probability density function(PDF) between the bucket signals and reference signals in thermal light ghost imaging, by regarding these signals as stochastic variables. The joint PDF allows us to ex...We present the joint probability density function(PDF) between the bucket signals and reference signals in thermal light ghost imaging, by regarding these signals as stochastic variables. The joint PDF allows us to examine the fractional-order moments of the bucket and the reference signals, in which the correlation orders are fractional numbers,other than positive integers in previous studies. The experimental results show that various images can be reconstructed from fractional-order moments. Negative(positive) ghost images are obtained with negative(positive) orders of the bucket signals. The visibility and peak signal-to-noise ratios of the diverse ghost images depend greatly on the fractional orders.展开更多
The prolongation structure methodologies of Wahlquist-Estabrook [H.D. Wahlquist and F.B. Estabrook, J. Math. Phys. 16 （1975） 1] for nonlinear differential equations are applied to a more general set of coupled integ...The prolongation structure methodologies of Wahlquist-Estabrook [H.D. Wahlquist and F.B. Estabrook, J. Math. Phys. 16 （1975） 1] for nonlinear differential equations are applied to a more general set of coupled integrable dispersionless system. Based on the obtained prolongation structure, a Lie-Algebra valued connection of a closed ideal of exterior differential forms related to the above system is constructed. A Lie-Algebra representation of some hidden structural symmetries of the previous system, its Biicklund transformation using the Riccati form of the linear eigenvalue problem and their general corresponding Lax-representation are derived. In the wake of the previous results, we extend the above prolongation scheme to higher-dimensional systems from which a new （2 ＋ 1）-dimensional coupled integrable dispersionless system is unveiled along with its inverse scattering formulation, which applications are straightforward in nonlinear optics where additional propagating dimension deserves some attention.展开更多
Topological materials host robust properties,unaffected by microscopic perturbations,owing to the global topological properties of the bulk electron system.Materials in which the topological invariant can be changed b...Topological materials host robust properties,unaffected by microscopic perturbations,owing to the global topological properties of the bulk electron system.Materials in which the topological invariant can be changed by easily tuning external parameters are especially sought after.Zirconium pentatelluride(ZrTe_(5))is one of a few experimentally available materials that reside close to the boundary of a topological phase transition,allowing the switching of its invariant by mechanical strain.Here,we unambiguously identify a topological insulator–metal transition as a function of strain,by a combination of ab initio calculations and direct measurements of the local charge density.Our model quantitatively describes the response to complex strain patterns found in bubbles of few layer ZrTe_(5) without fitting parameters,reproducing the mechanical deformation-dependent closing of the band gap observed using scanning tunneling microscopy.We calculate the topological phase diagram of ZrTe_(5) and identify the phase at equilibrium,enabling the design of device architectures,which exploit the topological switching characteristics of the system.展开更多
The accurate description of in-gap states of point defects in semiconductors with significant multideterminant character presents a long-standing challenge for density functional theory(DFT)methods.In this study,we de...The accurate description of in-gap states of point defects in semiconductors with significant multideterminant character presents a long-standing challenge for density functional theory(DFT)methods.In this study,we devise an ab initio methodology based on wavefunction theory(WFT)as a competing alternative approach.Specifically,we apply perturbation theory(NEVPT2)on top of a defect-localized many-body wavefunction(CASSCF).This quantum chemistry methodology,exemplified for the NV−center in diamond,is not only used for the calculation of energies and properties,but also for state-specific geometry optimization.By relaxing cluster models of increasing size and investigating convergence behavior,we accurately computed(i)the energy levels of NV−electronic states involved in the polarization cycle,(ii)the effect of Jahn-Teller distortion onmeasurable properties,(iii)the fine structure of ground and excited states,and(iv)the pressure dependence of zero-phonon lines.In addition,we predict hitherto uncharacterized high-lying excited states.展开更多
The negatively charged boron vacancy(V_(B)^(-))defect in hexagonal boron nitride has recently emerged as a promising spin qubit for sensing due to its high-temperature spin control and versatile integration into van d...The negatively charged boron vacancy(V_(B)^(-))defect in hexagonal boron nitride has recently emerged as a promising spin qubit for sensing due to its high-temperature spin control and versatile integration into van der Waals structures.While extensive experiments have explored their coherence properties,much less is known about the spin relaxation time(T_(1))and its control parameter dependence.In this work,we develop a parameter-free spin dynamics model based on the cluster expansion technique to investigate T_(1)relaxation mechanisms at low temperature.Our results reveal that the V_(B)^(-)center constitutes a strongly coupled electron spin-nuclear spin core,which necessitates the inclusion of the coherent dynamics and derived memory effects of the three nearest-neighbor nitrogen nuclear spins.Using this framework,this work closely reproduces the experimentally observed T_(1)time at B=90 G and further predicts the T_(1)dependence on externalmagnetic field in the 0≤B≤2000Ginterval,when the spin relaxation is predominantly driven by electron-nuclear and nuclear-nuclear flip-flop processes mediated by hyperfine and dipolar interactions.This study establishes a reliable and scalable approach for describing T_(1)relaxation in V_(B)^(-)centers and offers microscopic insights to support future developments in nuclear-spin-based quantum technologies.展开更多
The flourishing of topological photonics in the last decade was achieved mainly due to developments in linear topological photonic structures.However,when nonlinearity is introduced,many intriguing questions arise.For...The flourishing of topological photonics in the last decade was achieved mainly due to developments in linear topological photonic structures.However,when nonlinearity is introduced,many intriguing questions arise.For example,are there universal fingerprints of the underlying topology when modes are coupled by nonlinearity,and what can happen to topological invariants during nonlinear propagation?To explore these questions,we experimentally demonstrate nonlinearity-induced coupling of light into topologically protected edge states using a photonic platform and develop a general theoretical framework for interpreting the mode-coupling dynamics in nonlinear topological systems.Performed on laser-written photonic Su-Schrieffer-Heeger lattices,our experiments show the nonlinear coupling of light into a nontrivial edge or interface defect channel that is otherwise not permissible due to topological protection.Our theory explains all the observations well.Furthermore,we introduce the concepts of inherited and emergent nonlinear topological phenomena as well as a protocol capable of revealing the interplay of nonlinearity and topology.These concepts are applicable to other nonlinear topological systems,both in higher dimensions and beyond our photonic platform.展开更多
The development of plasma-based accelerators has enabled the generation of very high brightness electron bunches of femtosecond duration,micrometer size and ultralow emittance,crucial for emerging applications includi...The development of plasma-based accelerators has enabled the generation of very high brightness electron bunches of femtosecond duration,micrometer size and ultralow emittance,crucial for emerging applications including ultrafast detection in material science,laboratory-scale free-electron lasers and compact colliders for high-energy physics.The precise characterization of the initial bunch parameters is critical to the ability to manipulate the beam properties for downstream applications.Proper diagnostic of such ultra-short and high charge density laser-plasma accelerated bunches,however,remains very challenging.Here we address this challenge with a novel technique we name as femtosecond ultrarelativistic electron microscopy,which utilizes an electron bunch from another laser-plasma accelerator as a probe.In contrast to conventional microscopy of using very low-energy electrons,the femtosecond duration and high electron energy of such a probe beam enable it to capture the ultra-intense space-charge fields of the investigated bunch and to reconstruct the charge distribution with very high spatiotemporal resolution,all in a single shot.In the experiment presented here we have used this technique to study the shape of a laser-plasma accelerated electron beam,its asymmetry due to the drive laser polarization,and its beam evolution as it exits the plasma.We anticipate that this method will significantly advance the understanding of complex beam-plasma dynamics and will also provide a powerful new tool for real-time optimization of plasma accelerators.展开更多
Engineering of the orbital angular momentum(OAM)of light due to interaction with photonic lattices reveals rich physics and motivates potential applications.We report the experimental creation of regularly distributed...Engineering of the orbital angular momentum(OAM)of light due to interaction with photonic lattices reveals rich physics and motivates potential applications.We report the experimental creation of regularly distributed quantized vortex arrays in momentum space by probing the honeycomb and hexagonal photonic lattices with a single focused Gaussian beam.For the honeycomb lattice,the vortices are associated with Dirac points.However,we show that the resulting spatial patterns of vortices are strongly defined by the symmetry of the wave packet evolving in the photonic lattices and not by their topological properties.Our findings reveal the underlying physics by connecting the symmetry and OAM conversion and provide a simple and efficient method to create regularly distributed multiple vortices from unstructured light.展开更多
Isoprenoids are a very large and diverse family of metabolites required by all living organisms.All isoprenoids derive fromthe double-bond isomers isopentenyl diphosphate(IPP)and dimethylallyl diphosphate(DMAPP),which...Isoprenoids are a very large and diverse family of metabolites required by all living organisms.All isoprenoids derive fromthe double-bond isomers isopentenyl diphosphate(IPP)and dimethylallyl diphosphate(DMAPP),which are produced by the methylerythritol 4-phosphate(MEP)pathway in bacteria and plant plastids.It has been reported that IPP and DMAPP feedback-regulate the activity of deoxyxylulose 5-phosphate synthase(DXS),a dimeric enzyme that catalyzes the main flux-controlling step of the MEP pathway.Here we provide experimental insights intotheunderlyingmechanism.Isothermal titration calorimetry and dynamic light scattering approaches showed that IPP and DMAPP can allosterically bind to DXS in vitro,causing a size shift.In silico ligand binding site analysis and docking calculations identified a potential allosteric site in the contact region between the two monomers of the active DXS dimer.Modulation of IPP and DMAPP contents in vivo followed by immunoblot analyses confirmed that high IPP/DMAPP levels resulted in monomerization and eventual aggregation of the enzyme in bacterial and plant cells.Loss of the enzymatically active dimeric conformation allows a fast and reversible reduction of DXS activity in response to a sudden increase or decrease in IPP/DMAPP supply,whereas aggregation and subsequent removal of monomers that would otherwise be available for dimerization appears to be a more drastic response in the case of persistent IPP/DMAPP overabundance(e.g.,by a blockage in their conversion to downstream isoprenoids).Our results represent an important step toward understanding the regulation of the MEP pathway and rational design of biotechnological endeavors aimed at increasing isoprenoid contents in microbial and plant systems.展开更多
基金Project supported by the Fundamental Research Foundation for the Central Universities of China
文摘A quantum chain model of multiple molecule motors is proposed as a mathematical physics theory for the microscopic modeling of classical force-velocity relation and tension transients in muscle fibers. The proposed model was a quantum many-particle Hamiltonian to predict the force-velocity relation for the slow release of muscle fibers, which has not yet been empirically defined and was much more complicated than the hyperbolic relationships. Using the same Hamiltonian model, a mathematical force-velocity relationship was proposed to explain the tension observed when the muscle was stimulated with an alternative electric current. The discrepancy between input electric frequency and the muscle oscillation frequency could be explained physically by the Doppler effect in this quantum chain model. Further more, quantum physics phenomena were applied to explore the tension time course of cardiac muscle and insect flight muscle. Most of the experimental tension transient curves were found to correspond to the theoretical output of quantum two- and three-level models. Mathematical modeling electric stimulus as photons exciting a quantum three-level particle reproduced most of the tension transient curves of water bug Lethocerus maximus.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11775100,12247101,and 11961131009)the financial support from the China Scholarship Council(Grant No.CSC202306180087)the financial support from the Institute for Basic Science in Korea(Grant No.IBS-R024-D1)。
文摘We report on the theoretical and experimental investigations of the transition of a typical quantum system with mixed regular-integrable classical dynamics to one with violated time-reversal(T)invariance.The measurements are performed with a flat superconducting microwave resonator with circular shape in which chaoticity is induced by using either long antennas or inserting two circular disks into the cavity,and by magnetizing a ferrite disk placed at its center,which leads to violation of T invariance.We propose an extension of the Rosenzweig-Porter(RP)model,which interpolates between mixed regular-chaotic instead of integrable dynamics and fully chaotic dynamics with violated T-invariance,and derive a Wigner-surmise like analytical expression for the corresponding nearest-neighbor spacing distribution.We propose a procedure involving this result and those for the RP model to determine the size of T-invariance violation and chaoticity and validate it employing the experimental eigenfrequency spectra.
基金supported by the Fondation Jacques Toledano and the Schwartz-Reisman Center for Intense Laser Physics,and by ERC PoC Vherapy and EIC ebeam4therapy grants.
文摘Density downramp injection has been demonstrated to be an elegant and efficient approach for generating high-quality electron beams in laser wakefield accelerators.Recent studies have demonstrated the possibilities of generating electron beams with charges ranging from tens to hundreds of picocoulombs while maintaining good beam quality.However,the plasma and laser parameters in these studies have been limited to specific ranges or attention has been focused on separate physical processes such as beam loading,which affects the uniformity of the accelerating field and thus the energy spread of the trapped electrons,the repulsive force from the rear spike of the bubble,which reduces the transverse momentum P⊥of the trapped electrons and results in small beam emittance,and the laser evolution when traveling in the plasma.In this work,we present a comprehensive numerical study of downramp injection in the laser wakefield,and we demonstrate that the current profile of the injected electron beam is directly correlated with the density transition parameters,which further affects the beam charge and energy evolution.By fine-tuning the plasma density parameters,electron beams with high charge(up to several hundreds of picocoulombs)and low energy spread(around 1%FWHM)can be obtained.All these results are supported by large-scale quasi-threedimensional particle-in-cell simulations.We anticipate that the electron beams with tunable beam properties generated using this approach will be suitable for a wide range of applications.
基金supported by Hibah Penelitian Berbasi Kompetensi 2018 RISTEKDIKTI Republic of Indonesia
文摘The tunneling current in a graphene nanoribbon tunnel field effect transistor(GNR-TFET) has been quantum mechanically modeled. The tunneling current in the GNR-TFET was compared based on calculations of the Dirac-like equation and Schrodinger’s equation. To calculate the electron transmittance, a numerical approach-namely the transfer matrix method(TMM)-was employed and the Launder formula was used to compute the tunneling current. The results suggest that the tunneling currents that were calculated using both equations have similar characteristics for the same parameters, even though they have different values. The tunneling currents that were calculated by applying the Dirac-like equation were lower than those calculated using Schrodinger’s equation.
文摘A steady state analysis of the nonclassical features and statistical properties of the cavity radiation of a two- photon coherent beat laser is presented. Results show that the degree of two-mode squeezing, detectable entanglement and intensity of the cavity radiation can increase with the deviation of the phase fluctuations of the laser employed in preparing the atoms, but decrease with the increasing rate at which the induced coherence superposition decays. Although it is found that varying the phase fluctuations and dephasing can lead to modification in the quantum features and statistical properties of the radiation, it does not alter the similarity in the nature of the degree of entanglement detectable by the criteria following from Duan-Giedke-Cirac Zoller and logarithmic negativity in a perceivable manner. Since the intensity and quantum features can be readily enhanced, this system is expected to be a viable source of a strong robust entangled （squeezed） light under various conditions. Moreover, comparison of the mean number of photon pairs with intensity difference shows that the chance of inciting a two-photon process can be enhanced by changing the rate of dephasing and phase fluctuations.
基金National Natural Science Foundation of China(Grant No.12074438)The calculations reported were performed on resources provided by the Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices(Grant No.2022B1212010008).
文摘This topical review article reports rapid progress on the generalization and application of entanglement in non-Hermitian free-fermion quantum systems.We begin by examining the realization of non-Hermitian quantum systems through the Lindblad master equation,alongside a review of typical non-Hermitian free-fermion systems that exhibit unique features.A pedagogical discussion is provided on the relationship between entanglement quantities and the correlation matrix in Hermitian systems.Building on this foundation,we focus on how entanglement concepts are extended to non-Hermitian systems from their Hermitian free-fermion counterparts,with a review of the general properties that emerge.Finally,we highlight various concrete studies,demonstrating that entanglement entropy remains a powerful diagnostic tool for characterizing non-Hermitian physics.The entanglement spectrum also reflects the topological characteristics of non-Hermitian topological systems,while unique non-Hermitian entanglement behaviors are also discussed.The review is concluded with several future directions.Through this review,we hope to provide a useful guide for researchers who are interested in entanglement in non-Hermitian quantum systems.
文摘Modulational instability conditions for the generation of localized structures in the context of matter waves in Bose-Einstein condensates are investigated analytically and numerically. The model is based on a modified Gross-Pitaevskii equation, which account for the energy dependence of the two-body scattering amplitude. It is shown that the modified term due to the quantum fluctuations modify significantly the modulational instability gain. Direct numerical simulations of the full modified Gross-Pitaevskii equation are performed, and it is found that the modulated plane wave evolves into a train of pulses, which is destroyed at longer times due to the effects of quantum fluctuations.
文摘Ionizing radiation (IR) is the most common treatment used to control localized primary prostate cancer (PC). However, for a significant number of patients, radiotherapy fails to adequately control the tumor. Thus, a main clinical problem today is the lack of a specific marker that may be used to predict the treatment outcome and to identify prostate cancer patients who are unlikely to respond to radiation therapy. In this study, we used human PC xenografts with predetermined radioresistant/sensitive phenotypes, and gene expression microarrays, correlated their specific transcripttional profiles with response to radiation. Employing unsupervised two-way hierarchical clustering, we identified four gene clusters displaying different expression patterns. Two clusters showed higher expression levels in the resistant xenografts and the other two clusters showed higher expression levels in the sensitive xenografts. Expression levels of 113 genes differed by at least 3 fold between sensitive and resistant xenografts. These genes represent members of several cellular pathways, some of which are known to be associated with response to radiation. All or several of these genes could serve as predictive tools to determine at biopsy the expected response of a particular tumor to radiotherapy. Indeed, the profiles we identified enabled us to predict the degree of radiosensitivity of a panel of established PC cell lines. Importantly, irradiation of the PC xenografts did not induce any significant changes in gene expression, regardless of their susceptibility phenotype. These data strongly support the first of two models: a: a random effect of irradiation on a homogeneous population of cells, rather than b: of a tumor comprised of a mixture of radioresistant and radiosensitive cell subpopulations. Our findings imply that each of the radio-phenotypes represents different intrinsic characteristics that affect the ability of a tumor to survive radiotherapy.
基金The authors extend their appreciation to the Deanship of Scientific Research and Libraries in Princess Nourah bint Abdulrahman University for funding this research work through the Research Group project under Grant No.(RG-1445-0005).
文摘This study investigates the dromion structure within the context of(2+1)-dimensional modulated positron-acoustic waves in a magnetoplasma consisting of inertial cold positrons and inertialess nonthermal hot electrons and positrons as well as stationary positive ions.The reductive perturbation approach reduces the fluid governing equations to the plasma model to a Davey–Stewartson system.This study provides a detailed analysis of the influence of many related plasma parameters,including the density ratio of hot and cold positrons,the external magnetic field strength,the nonthermal parameter and the density ratio of electrons and cold positrons,on the growing rate of instability.Using the Hirota Bilinear method,it is found that the system supports some exact solutions,such as one-and two-dromion solutions.The change of plasma parameters significantly enhances the characteristics of dromion solutions.The elastic and inelastic collisions between two dromions are discussed at different times.The relevance of this study can help us to understand the various types of collision between energetic particles in confined plasma during the production of energy by thermonuclear fusion.
基金funding from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement no.801459-FP-RESOMUSfunding by the Chemical Sciences,Geosciences and Biosciences Division,Office of Basic Energy Sciences,Office of Science,US Department of Energy,grant no.DE-FG02-86ER13491supported by ETH Zurich and the Swiss National Science Foundation through projects 200021_172946 and the NCCR-MUST.
文摘The Fano line shape,arising from the interference of pathways for the excitation of discrete and continuum states,plays a fundamental role in many branches of physics,chemistry,and materials science.Exciting the resonance with a high harmonic provides naturally a phase delay between the pathways leading to a complex asymmetry parameter.We demonstrate that its amplitude and phase can be controlled on the femtosecond and attosecond time scales,respectively.With our high-energy-resolution(10-meV)experiment,we dynamically image a resonance-enhanced electron wave packet during its temporal evolution,extracting both the amplitude and the phase.Calculations reproduce our experimental results.Our approach constitutes a method for measuring the photoionization delays of a resonance and enables the reconstruction of the electron wave packet in the time domain.This concept of an interferencecontrolled Fano line shape is a step toward attosecond quantum optics with potential ramifications into nanoscience and next-generation optical materials.
文摘自旋是基本粒子(电子、光子)角动量的内在形式.固体中体现自旋特征的集体电子行为如拓扑绝缘体等是当前凝聚态物理领域关注的焦点,是基态行为.激子作为电子空穴对的激发态且寿命很短,可复合发光,它是否能体现自旋极化主导的行为?对此人们的认识远不如针对基态的电子.激子磁极化子(exciton magnetic polaron, EMP)是由磁性半导体微结构中铁磁自旋耦合态与自由激子相互作用形成的复合元激发,但其研究很有限.本文概述了我们在稀磁半导体微纳米结构中的EMP及其发光动态学光谱、自旋极化激子凝聚态的形成方面取得的一些进展,展望了未来可能在自旋光电子器件、磁控激光、光致磁性等量子技术方面的潜在应用.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11674273,11304016,and 11204062)
文摘We present the joint probability density function(PDF) between the bucket signals and reference signals in thermal light ghost imaging, by regarding these signals as stochastic variables. The joint PDF allows us to examine the fractional-order moments of the bucket and the reference signals, in which the correlation orders are fractional numbers,other than positive integers in previous studies. The experimental results show that various images can be reconstructed from fractional-order moments. Negative(positive) ghost images are obtained with negative(positive) orders of the bucket signals. The visibility and peak signal-to-noise ratios of the diverse ghost images depend greatly on the fractional orders.
文摘The prolongation structure methodologies of Wahlquist-Estabrook [H.D. Wahlquist and F.B. Estabrook, J. Math. Phys. 16 （1975） 1] for nonlinear differential equations are applied to a more general set of coupled integrable dispersionless system. Based on the obtained prolongation structure, a Lie-Algebra valued connection of a closed ideal of exterior differential forms related to the above system is constructed. A Lie-Algebra representation of some hidden structural symmetries of the previous system, its Biicklund transformation using the Riccati form of the linear eigenvalue problem and their general corresponding Lax-representation are derived. In the wake of the previous results, we extend the above prolongation scheme to higher-dimensional systems from which a new （2 ＋ 1）-dimensional coupled integrable dispersionless system is unveiled along with its inverse scattering formulation, which applications are straightforward in nonlinear optics where additional propagating dimension deserves some attention.
基金The work was conducted within the framework of the Topology in Nanomaterials Lendulet project,Grant No.LP2017-9/2017with support from the European H2020 GrapheneCore3 Project No.881603+3 种基金Financial support fromÉlvonal Grant KKP 138144,NKFIH OTKA grant K132869 and TKP20121 NKPA grant is also acknowledgedP.V.and L.O.acknowledge the support of the Janos Bolyai Research Scholarship the Bolyai+Scholarship of the Hungarian Academy of SciencesL.O.acknowledges financial support from NKFIH OTKA grant FK124723 and K131938L.O.and J.K.acknowledges the support from the Ministry of Innovation and Technology for the Quantum Information National Laboratory.
文摘Topological materials host robust properties,unaffected by microscopic perturbations,owing to the global topological properties of the bulk electron system.Materials in which the topological invariant can be changed by easily tuning external parameters are especially sought after.Zirconium pentatelluride(ZrTe_(5))is one of a few experimentally available materials that reside close to the boundary of a topological phase transition,allowing the switching of its invariant by mechanical strain.Here,we unambiguously identify a topological insulator–metal transition as a function of strain,by a combination of ab initio calculations and direct measurements of the local charge density.Our model quantitatively describes the response to complex strain patterns found in bubbles of few layer ZrTe_(5) without fitting parameters,reproducing the mechanical deformation-dependent closing of the band gap observed using scanning tunneling microscopy.We calculate the topological phase diagram of ZrTe_(5) and identify the phase at equilibrium,enabling the design of device architectures,which exploit the topological switching characteristics of the system.
基金supported by the National Research,Development,and Innovation Office of Hungary within the Quantum Information National Laboratory of Hungary(Grant No.2022-2.1.1-NL-2022-00004)within grants FK 135496 and FK 145395+2 种基金V.I.also acknowledges the support from the Knut and Alice Wallenberg Foundation through the WBSQD2 project(Grant No.2018.0071)Z.B.and A.P.acknowledge the financial support of the János Bolyai Research Fellowship of the Hungarian Academy of SciencesThe computations were enabled by resources provided by the National Academic Infrastructure for Supercomputing in Sweden(NAISS)and the Swedish National Infrastructure for Computing(SNIC)at NSC,partially funded by the Swedish Research Council through grant agreements no.2022-06725 and no.2018-05973.The authors also acknowledge KIFÜfor awarding us computational resources at the Komondor supercomputer in Hungary.
文摘The accurate description of in-gap states of point defects in semiconductors with significant multideterminant character presents a long-standing challenge for density functional theory(DFT)methods.In this study,we devise an ab initio methodology based on wavefunction theory(WFT)as a competing alternative approach.Specifically,we apply perturbation theory(NEVPT2)on top of a defect-localized many-body wavefunction(CASSCF).This quantum chemistry methodology,exemplified for the NV−center in diamond,is not only used for the calculation of energies and properties,but also for state-specific geometry optimization.By relaxing cluster models of increasing size and investigating convergence behavior,we accurately computed(i)the energy levels of NV−electronic states involved in the polarization cycle,(ii)the effect of Jahn-Teller distortion onmeasurable properties,(iii)the fine structure of ground and excited states,and(iv)the pressure dependence of zero-phonon lines.In addition,we predict hitherto uncharacterized high-lying excited states.
基金supported by the National Research,Development and Innovation Office of Hungary(NKFIH)within the Quantum Information National Laboratory of Hungary(Grant No.2022-2.1.1-NL-2022-00004)within the project FK 145395+3 种基金funded by the European Commission within Horizon Europe projects(Grant Nos.101156088 and 101129663)This research is part of the Munich Quantum Valley,which is supported by the Bavarian state government with funds from the Hightech Agenda Bayern Plusfunded by the Deutsche Forschungsgemeinschaft(DFG,German Research Foundation)under Germany’s Excellence Strategy-EXC-2111-390814868(MCQST)as part of the CRC 1375 NOA project C2.The authors acknowledge support from the Federal Ministry of Research,Technology and Space(BMFTR)under grant number 13N16292(ATOMIQS).The authors gratefully acknowledge the Gauss Centre for Supercomputing e.V.(www.gauss-centre.eu)for funding this project by providing computing time on the GCS Supercomputer SuperMUC-NG at Leibniz Supercomputing Centre(www.lrz.de)and on its Linux-Cluster.
文摘The negatively charged boron vacancy(V_(B)^(-))defect in hexagonal boron nitride has recently emerged as a promising spin qubit for sensing due to its high-temperature spin control and versatile integration into van der Waals structures.While extensive experiments have explored their coherence properties,much less is known about the spin relaxation time(T_(1))and its control parameter dependence.In this work,we develop a parameter-free spin dynamics model based on the cluster expansion technique to investigate T_(1)relaxation mechanisms at low temperature.Our results reveal that the V_(B)^(-)center constitutes a strongly coupled electron spin-nuclear spin core,which necessitates the inclusion of the coherent dynamics and derived memory effects of the three nearest-neighbor nitrogen nuclear spins.Using this framework,this work closely reproduces the experimentally observed T_(1)time at B=90 G and further predicts the T_(1)dependence on externalmagnetic field in the 0≤B≤2000Ginterval,when the spin relaxation is predominantly driven by electron-nuclear and nuclear-nuclear flip-flop processes mediated by hyperfine and dipolar interactions.This study establishes a reliable and scalable approach for describing T_(1)relaxation in V_(B)^(-)centers and offers microscopic insights to support future developments in nuclear-spin-based quantum technologies.
基金supported by the National Key R&D Program of China under Grant No.2017YFA0303800the National Natural Science Foundation(11922408,91750204,11674180),PCSIRT+5 种基金the 111 Project(No.B07013)in Chinasupport in part by the Croatian Science Foundation Grant No.IP-2016-06-5885 SynthMagIAthe QuantiXLie Center of Excellence,a project co-financed by the Croatian Government and European Union through the European Regional Development Fund-the Competitiveness and Cohesion Operational Programme(Grant KK.01.1.1.01.0004)supported by the Australian Research Council(DE19010043)supported by the Institute for Basic Science in Korea(IBS-R024-Y1)support from the Russian Foundation for Basic Research(grant No.19-52-12053).
文摘The flourishing of topological photonics in the last decade was achieved mainly due to developments in linear topological photonic structures.However,when nonlinearity is introduced,many intriguing questions arise.For example,are there universal fingerprints of the underlying topology when modes are coupled by nonlinearity,and what can happen to topological invariants during nonlinear propagation?To explore these questions,we experimentally demonstrate nonlinearity-induced coupling of light into topologically protected edge states using a photonic platform and develop a general theoretical framework for interpreting the mode-coupling dynamics in nonlinear topological systems.Performed on laser-written photonic Su-Schrieffer-Heeger lattices,our experiments show the nonlinear coupling of light into a nontrivial edge or interface defect channel that is otherwise not permissible due to topological protection.Our theory explains all the observations well.Furthermore,we introduce the concepts of inherited and emergent nonlinear topological phenomena as well as a protocol capable of revealing the interplay of nonlinearity and topology.These concepts are applicable to other nonlinear topological systems,both in higher dimensions and beyond our photonic platform.
基金This work was supported by The Schwartz/Reisman Center for Intense Laser Physics,by a research grant from the Benoziyo Endowment Fund for the Advancement of Science,by the Israel Science Foundation,Minerva,Wolfson Foundation,the Schilling Foundation,R.Lapon,Dita&Yehuda Bronicki,and by the Helmholtz association.The simulations were carried out at the Weizmann Institute’s EXAscale Cluster(WEXAC).Y.W.would like to thank Aaron Liberman for improving the context,and thank Dr.Igor A.Andriyash from Laboratoire d’Optique Appliquée and Prof.Wei Lu from Tsinghua University for helpful discussions.
文摘The development of plasma-based accelerators has enabled the generation of very high brightness electron bunches of femtosecond duration,micrometer size and ultralow emittance,crucial for emerging applications including ultrafast detection in material science,laboratory-scale free-electron lasers and compact colliders for high-energy physics.The precise characterization of the initial bunch parameters is critical to the ability to manipulate the beam properties for downstream applications.Proper diagnostic of such ultra-short and high charge density laser-plasma accelerated bunches,however,remains very challenging.Here we address this challenge with a novel technique we name as femtosecond ultrarelativistic electron microscopy,which utilizes an electron bunch from another laser-plasma accelerator as a probe.In contrast to conventional microscopy of using very low-energy electrons,the femtosecond duration and high electron energy of such a probe beam enable it to capture the ultra-intense space-charge fields of the investigated bunch and to reconstruct the charge distribution with very high spatiotemporal resolution,all in a single shot.In the experiment presented here we have used this technique to study the shape of a laser-plasma accelerated electron beam,its asymmetry due to the drive laser polarization,and its beam evolution as it exits the plasma.We anticipate that this method will significantly advance the understanding of complex beam-plasma dynamics and will also provide a powerful new tool for real-time optimization of plasma accelerators.
基金supported by the National Key R&D Program of China(Grant Nos.2018YFA0307500 and 2023YFA1407100)the Key Scientific and Technological Innovation Team of Shaanxi Province(Grant No.2021TD-56)+7 种基金the National Natural Science Foundation of China(Grant Nos.12074303,62022066,12074306,and 11804267)the IBS Young Scientist Fellowship(Grant No.IBS-R024-Y3)the Basis Foundation(Grant No.21-1-3-30-1)the support of the European Union’s Horizon 2020 program,through an FET Open research and innovation action(Grant No.964770)(Topo Light)he ANR projects Labex Ga NEXT(Grant No.ANR-11-LABX0014)“NEWAVE”(Grant No.ANR-21-CE24-0019)the ANR program“Investissements d’Avenir”through the IDEX-ISITE initiative 16-IDEX-0001(Grant No.CAP 20-25)support by the Russian Science Foundation(Grant No.22-12-00144)
文摘Engineering of the orbital angular momentum(OAM)of light due to interaction with photonic lattices reveals rich physics and motivates potential applications.We report the experimental creation of regularly distributed quantized vortex arrays in momentum space by probing the honeycomb and hexagonal photonic lattices with a single focused Gaussian beam.For the honeycomb lattice,the vortices are associated with Dirac points.However,we show that the resulting spatial patterns of vortices are strongly defined by the symmetry of the wave packet evolving in the photonic lattices and not by their topological properties.Our findings reveal the underlying physics by connecting the symmetry and OAM conversion and provide a simple and efficient method to create regularly distributed multiple vortices from unstructured light.
基金funded by grants from the Spanish MCIN/AEI/10.13039/501100011033European ERDF/FEDER,NextGeneration EU/PRTR and PRIMA programs(PID2020-115810GB-I00+3 种基金UToPIQ-PCI2021-121941 to M.R.-C.and BFU2016-78232-P to A.V.-C.).M.R.-C.is also supported by CSIC(202040E299)Generalitat Valenciana(PROMETEU/2021/056).R.K.and E.E.K.B.conducted the metabolite analysis at the Joint BioEnergy Institute(http://www.jbei.org),supported by the US Department of Energy,Office of Science,Office of Biological and Environmental Research under contract DE-AC02-05CH11231 between Lawrence Berkeley National Laboratory and the US Department of Energy.J.P.-Gwas supported by a Marie Curie International Outgoing Fellowship within the EC-FP7 Program(project 627639)X.D.was supported by the China Scholarship Council and D.O.-A.by an MCIN/AEI/fellowship(BES-2017-080739).
文摘Isoprenoids are a very large and diverse family of metabolites required by all living organisms.All isoprenoids derive fromthe double-bond isomers isopentenyl diphosphate(IPP)and dimethylallyl diphosphate(DMAPP),which are produced by the methylerythritol 4-phosphate(MEP)pathway in bacteria and plant plastids.It has been reported that IPP and DMAPP feedback-regulate the activity of deoxyxylulose 5-phosphate synthase(DXS),a dimeric enzyme that catalyzes the main flux-controlling step of the MEP pathway.Here we provide experimental insights intotheunderlyingmechanism.Isothermal titration calorimetry and dynamic light scattering approaches showed that IPP and DMAPP can allosterically bind to DXS in vitro,causing a size shift.In silico ligand binding site analysis and docking calculations identified a potential allosteric site in the contact region between the two monomers of the active DXS dimer.Modulation of IPP and DMAPP contents in vivo followed by immunoblot analyses confirmed that high IPP/DMAPP levels resulted in monomerization and eventual aggregation of the enzyme in bacterial and plant cells.Loss of the enzymatically active dimeric conformation allows a fast and reversible reduction of DXS activity in response to a sudden increase or decrease in IPP/DMAPP supply,whereas aggregation and subsequent removal of monomers that would otherwise be available for dimerization appears to be a more drastic response in the case of persistent IPP/DMAPP overabundance(e.g.,by a blockage in their conversion to downstream isoprenoids).Our results represent an important step toward understanding the regulation of the MEP pathway and rational design of biotechnological endeavors aimed at increasing isoprenoid contents in microbial and plant systems.
