Quantum many-body systems lie at the heart of modern fundamental physics.The study of these systems has revealed a plethora of fascinating phenomena,such as quantum thermalization,many-body localization,and quantum ma...Quantum many-body systems lie at the heart of modern fundamental physics.The study of these systems has revealed a plethora of fascinating phenomena,such as quantum thermalization,many-body localization,and quantum many-body scars.This review provides a comprehensive overview of the recent advances in understanding quantum many-body scars and non-ergodic dynamics in quantum systems on superconducting-circuit platforms,ranging from theoretical mechanisms and effective models to experimental observations.展开更多
Based on atomic crystal configurations,we studied many-body interaction properties of face-centered cubic(fcc)solid argon(Ar)within the atomic distance range of 2.0A to 3.6A at T=300 K.The resulting EOS can accurately...Based on atomic crystal configurations,we studied many-body interaction properties of face-centered cubic(fcc)solid argon(Ar)within the atomic distance range of 2.0A to 3.6A at T=300 K.The resulting EOS can accurately describe the compression behavior of solid Ar under the experimentally investigated pressure range(0~114GPa).Statistically,903(Ar)2 clusters were identified,corresponding to 12 distinct geometric configurations,861(Ar)3 clusters correspond to 25 distinct geometric configurations,816(Ar)4clusters correspond to 27 distinct geometric configurations,and the calculation results exhibited good convergence.For comparative purposes,the EOS of fcc solid Ar was also calculated using a two-body potential-only approach,which showed excellent agreement with experimental data under relevant pressures.Incorporating three-body terms extended the EOS accuracy to 80 GPa,while the inclusion of four-body terms further improved the precision up to 114 GPa.Higher-order many-body terms are expected to enable accurate interpretation of experimental phenomena in solid Ar above 114 GPa.In addition,when the molar volume is reduced to a fixed value,the zero-point vibration pressure has already reached a certain proportion,then it must be considered and cannot be ignored.This study provides a reliable theoretical model for the study of high-pressure properties and zero-point energy of rare gas solids.展开更多
In this paper, we deduce the analytical form of many-body interatomic potentials based on the Green's function in tight-binding representation. The many-body potentials are expressed as the functions of the hoppin...In this paper, we deduce the analytical form of many-body interatomic potentials based on the Green's function in tight-binding representation. The many-body potentials are expressed as the functions of the hopping integrals which are the physical origin of cohesion of atoms. For thesimple case of s-valent system, the inversion of the many-body potentials are discussed in detail by using the lattice inversion method.展开更多
Quantum simulation has been developed extensively over the past decades,widely applied to different models to explore dynamics in the quantum regime.Rydberg atoms have strong dipole-dipole interactions and interact wi...Quantum simulation has been developed extensively over the past decades,widely applied to different models to explore dynamics in the quantum regime.Rydberg atoms have strong dipole-dipole interactions and interact with each other over a long distance,which makes it straightforward to build many-body interacting quantum systems to simulate specific models.Additionally,neutral atoms are easily manipulated due to their weak interactions.These advantages make Rydberg many-body system an ideal platform to implement quantum simulations.This paper reviews several quantum simulations for different models based on Rydberg many-body systems,including quantum Ising models in one dimension and two dimensions mainly for quantum magnetism,XY model for excitation transport,SSH model for symmetry-protected topological phases,and critical self-organized behaviors in many-body systems.Besides,some challenges and promising directions of quantum simulations based on Rydberg many-body system are discussed in this paper.展开更多
This article presents an elementary introduction on various aspects of the prototypical integrable model the LiebLiniger Bose gas ranging from the cooperative to the collective features of many-body phenomena. In 1963...This article presents an elementary introduction on various aspects of the prototypical integrable model the LiebLiniger Bose gas ranging from the cooperative to the collective features of many-body phenomena. In 1963, Lieb and Liniger first solved this quantum field theory many-body problem using Bethe＇s hypothesis, i.e., a particular form of wavefunction introduced by Bethe in solving the one-dimensional Heisenberg model in 1931. Despite the Lieb-Liniger model is arguably the simplest exactly solvable model, it exhibits rich quantum many-body physics in terms of the aspects of mathematical integrability and physical universality. Moreover, the Yang-Yang grand canonical ensemble description for the model provides us with a deep understanding of quantum statistics, thermodynamics, and quantum critical phenomena at the many-body physical level. Recently, such fundamental physics of this exactly solved model has been attracting growing interest in experiments. Since 2004, there have been more than 20 experimental papers that rbported novel observations of different physical aspects of the Lieb--Liniger model in the laboratory. So far the observed results are in excellent agreement with results obtained using the analysis of this simplest exactly solved model. Those experimental observations reveal the unique beauty of integrability.展开更多
The necessary derivation of negative mass in dispersion dynamics suggests cosmic applications. The method analyzes functional relationships between particle angular frequency, wave vector, rest mass and electromagneti...The necessary derivation of negative mass in dispersion dynamics suggests cosmic applications. The method analyzes functional relationships between particle angular frequency, wave vector, rest mass and electromagnetic or nuclear potential, f(ω, k, m0, V) = 0. A summary of consequential predictions of the dynamics leads to a calculation of ways in which negative mass might influence such phenomena as the rotational velocities that are observed in spiral galaxies. The velocities are found to be not Newtonian in the simple two body approximations for our solar system;but nearly constant with increasing orbital radii. It has moreover been suggested that the motion is due to halo structures of dark matter or dark energy. However, the motion is simply described by many-body gravitation that is transmitted along elastic spiral arms. In this context, we calculate possible effects of negative mass, but without observational confirmation.展开更多
Employing the advanced relativistic configuration interaction(RCI)combined with the many-body perturbation theory(RMBPT)method,we report energies and lifetime values for the lowest 35 energy levels from the(1s^(2))nl ...Employing the advanced relativistic configuration interaction(RCI)combined with the many-body perturbation theory(RMBPT)method,we report energies and lifetime values for the lowest 35 energy levels from the(1s^(2))nl configurations(where the principal quantum number n=2–6 and the angular quantum number l=0,...,n-1)of lithium-like iron Fe XXIV,as well as complete data on the transition wavelengths,radiative rates,absorption oscillator strengths,and line strengths between the levels.Both the allowed(E1)and forbidden(magnetic dipole M1,magnetic quadrupole M2,and electric quadrupole E2)ones are reported.Through detailed comparisons with previous results,we assess the overall accuracies of present RMBPT results to be likely the most precise ones to date.Configuration interaction effects are found to be very important for the energies and radiative properties for the ion.The present RMBPT results are valuable for spectral line identification,plasma modeling,and diagnosing.展开更多
In this paper, an extended spectral theorem is given, which enables one to calculate the correlation functions when complex eigenvalues appear. To do so, a Fourier transformation with a complex argument is utilized. W...In this paper, an extended spectral theorem is given, which enables one to calculate the correlation functions when complex eigenvalues appear. To do so, a Fourier transformation with a complex argument is utilized. We treat all the Matsbara frequencies, including Fermionic and Bosonic frequencies, on an equal footing. It is pointed out that when complex eigenvalues appear, the dissipation of a system cannot simply be ascribed to the pure imaginary part of the Green function. Therefore, the use of the name fluctuation-dissipation theorem should be careful.展开更多
Heat and mass transfer during the process of liquid droplet dynamic behaviors has attracted much attention in decades.At mesoscopic scale,numerical simulations of liquid droplets motion,such as impacting,sliding,and c...Heat and mass transfer during the process of liquid droplet dynamic behaviors has attracted much attention in decades.At mesoscopic scale,numerical simulations of liquid droplets motion,such as impacting,sliding,and coalescence,have been widely studied by using the particle-based method named many-body dissipative particle dynamics(MDPD).However,the detailed information on heat transfer needs further description.This paper develops a modified MDPD with energy conservation(MDPDE)by introducing a temperature-dependent long-term attractive interaction.By fitting or deriving the expressions of the strength of the attractive force,the exponent of the weight function in the dissipative force,and the mesoscopic heat friction coefficient about temperature,we calculate the viscosity,self-diffusivity,thermal conductivity,and surface tension,and obtain the Schmidt number Sc,the Prandtl number P r,and the Ohnesorge number Oh for 273 K to 373 K.The simulation data of MDPDE coincide well with the experimental data of water,indicating that our model can be used to simulate the dynamic behaviors of liquid water.Furthermore,we compare the equilibrium contact angle of droplets wetting on solid surfaces with that calculated from three interfacial tensions by MDPDE simulations.The coincident results not only stand for the validation of Young’s equation at mesoscale,but manifest the reliability of our MDPDE model and applicability to the cases with free surfaces.Our model can be extended to study the multiphase flow withcomplex heat and mass transfer.展开更多
Although the many-body expansion(MBE)approach is widely applied to estimate the energy of large systems containing weak interactions,it is inapplicable to calculating the energies of covalent or metal clusters.In this...Although the many-body expansion(MBE)approach is widely applied to estimate the energy of large systems containing weak interactions,it is inapplicable to calculating the energies of covalent or metal clusters.In this work,we propose an interaction manybody expansion(IMBE)to calculate the energy of atomic clusters containing covalent bonds.In this approach,the energy of a system is expressed as the sum of the energy of atoms and the interaction energy between the atom and its surrounding atoms.The IMBE method is first applied to calculate the energies of nitrogen clusters,in which the interatomic interactions are truncated to four-body terms.The results show that the IMBE approach could significantly reduce the energy error for nitrogen clusters compared with the traditional MBE method.The weak size and structure dependence of the IMBE error with respect to DFT calculations indicates the IMBE method has good potential application in estimating energy of large covalent systems.展开更多
We study the charge oscillation in the triangular quantum dots symmetrically coupled to the leads. A strong charge oscillation is observed even for a very small level difference. We attribute this oscillation behaviou...We study the charge oscillation in the triangular quantum dots symmetrically coupled to the leads. A strong charge oscillation is observed even for a very small level difference. We attribute this oscillation behaviour to the many- body effect in the strongly correlated system instead of the physical scenarios based on the mean-field approach in the previous works for the two-level dot. The level difference induces the difference of the occupations between different dots, while the symmetry of the many-body states favours the homogeneous distribution of the charge density on the three dots. The interplay of these two factors results in the charge oscillation.展开更多
In this paper the tensor probability current and continuity equation is obtained, with this the correlated cross section of many particle scattering can be evaluation.
Investigation of quantum criticality in condensed matter systems not only reveals universal behaviors of quantum phase transitions but also deepens our understanding of emergent physics in quantum many-body systems.Wi...Investigation of quantum criticality in condensed matter systems not only reveals universal behaviors of quantum phase transitions but also deepens our understanding of emergent physics in quantum many-body systems.With accurate descriptions of the ground states and low-energy excitations of(quasi-)one-dimensional(1D)quantum spin models,significant progress has been made in studying quantum criticality and related emergent physics.In this review,we provide a short survey on some recent developments in this field.We start by discussing critical thermodynamics and dynamics of transverse-field Ising chain,highlighting novel quantum integrability and many-body excitations upon relevant perturbations.Dynamical properties of the excitations are further discussed,along with their experimental verification.Along the line of integrability,we further discuss the Heisenberg-Ising chain,introducing the string magnetic state.Among them,non-trivial string solutions which go beyond conventional field theory,have also been observed in experiments.Apart from the critical phenomena associated with the standard Ginzburg-Landau paradigm,we introduce the deconfined quantum criticality,which arises as a consequence of a continuous phase transition between two ordered states.Such a transition goes beyond the description of the Ginzburg-Landau paradigm and is characterized by the emergence of fractionalized spin excitations and enhanced continuous symmetry at the quantum critical point.Finally,we conclude by highlighting potential novel critical phenomena and emergent physics and their realizations in quasi-1D quantum magnetic systems.展开更多
It has been demonstrated that the Rydberg criticality in a many-body atomic system can enhance the measurement sensitivity of the microwave electric field by increasing the Fisher information.In our previous work,we p...It has been demonstrated that the Rydberg criticality in a many-body atomic system can enhance the measurement sensitivity of the microwave electric field by increasing the Fisher information.In our previous work,we proposed and experimentally verified that the Fisher information near the critical point can be increased by more than two orders of magnitude with the Rydberg atoms coupled with an optical cavity compared with that in free space.Here we demonstrate the precision measurement of the microwave electric field by cavity-enhanced critical behavior.We show that the equivalent measurement sensitivity of the microwave electric field can be enhanced by an order of magnitude compared with that in free space.The obtained sensitivity can be enhanced to 2.6 nV cm^(−1) Hz^(−1/2).展开更多
Non-equilibrium dynamics of quantum many-body systems has attracted increasing attention owing to a variety of intriguing phenomena absent in equilibrium physics.A prominent example is the quantum Mpemba effect,where ...Non-equilibrium dynamics of quantum many-body systems has attracted increasing attention owing to a variety of intriguing phenomena absent in equilibrium physics.A prominent example is the quantum Mpemba effect,where subsystem symmetry is restored more rapidly under a symmetric quench from a more asymmetric initial state.In this work,we investigate symmetry restoration and the quantum Mpemba effect in many-body localized systems for a range of initial states.We show that symmetry can still be restored in the many-body localization regime without approaching thermal equilibrium.Moreover,we demonstrate that the quantum Mpemba effect emerges universally for any tilted product state,in contrast to chaotic systems where its occurrence depends sensitively on the choice of the initial state.We further provide a theoretical analysis of symmetry restoration and the quantum Mpemba effect using an effective model for many-body localization.Overall,this paper fills an important gap in establishing a unified understanding of symmetry restoration and the quantum Mpemba effect in generic many-body systems,and it advances our understanding of many-body localization.展开更多
Variational quantum algorithms have been widely demonstrated in both experimental and theoretical contexts to have extensive applications in quantum simulation,optimization,and machine learning.However,the exponential...Variational quantum algorithms have been widely demonstrated in both experimental and theoretical contexts to have extensive applications in quantum simulation,optimization,and machine learning.However,the exponential growth in the dimension of the Hilbert space results in the phenomenon of vanishing parameter gradients in the circuit as the number of qubits and circuit depth increase,known as the barren plateau phenomena.In recent years,research in non-equilibrium statistical physics has led to the discovery of the realization of many-body localization.As a type of floquet system,many-body localized floquet system has phase avoiding thermalization with an extensive parameter space coverage and has been experimentally demonstrated can produce time crystals.We applied this circuit to the variational quantum algorithms for the calculation of many-body ground states and studied the variance of gradient for parameter updates under this circuit.We found that this circuit structure can effectively avoid barren plateaus.We also analyzed the entropy growth,information scrambling,and optimizer dynamics of this circuit.Leveraging this characteristic,we designed a new type of variational ansatz,called the“many-body localization ansatz”.We applied it to solve quantum many-body ground states and examined its circuit properties.Our numerical results show that our ansatz significantly improved the variational quantum algorithm.展开更多
Hilbert space fragmentation(HSF)is a mechanism for generating quantum many-body scar(QMBS),which provides a route to weakly break ergodicity.Many scarred systems possess an exponentially large number of zeroenergy sta...Hilbert space fragmentation(HSF)is a mechanism for generating quantum many-body scar(QMBS),which provides a route to weakly break ergodicity.Many scarred systems possess an exponentially large number of zeroenergy states due to the chiral symmetry induced bipartition of the Hilbert space.In this work,we study the QMBS phenomenology under the interplay between the chiral symmetry and pseudo HSF,where the Hilbert space is approximately fragmented into different blocks.We consider a model of tilted chain of interacting spinless fermions with periodically varying tunneling strength.At small tunneling strength,we analytically derive the resonance conditions under which the system is described by an effective model with chiral symmetry and pseudo HSF.We find that the interplay between the two gives rise to a highly localized zero-energy QMBS when the particle number is even.This zero-energy QMBS induces an unusual scarred dynamical phenomenon.Specifically,the fidelity from a simple initial state oscillates around a finite fixed value without decaying,instead of showing the typical decaying collapse and revival observed when the particle number is odd and in common scarred systems.We show that the signature of the unusual scarred dynamical behaviour can also be detected in the original driven system by measuring local observables.Our findings enrich the scar phenomenon and deepen the understanding of the relation between Hilbert space structure and QMBS.展开更多
We investigate the quantum many-body dynamics of ultracold atom–molecule conversion using a Floquet spin-boson model,where the periodic energy detuning between molecules and atomic pairs is utilized to explore variou...We investigate the quantum many-body dynamics of ultracold atom–molecule conversion using a Floquet spin-boson model,where the periodic energy detuning between molecules and atomic pairs is utilized to explore various dynamical regimes.We find that the upper bound of the adiabatic driving frequency increases continuously with the strength of molecule–molecule interactions,indicating that many-body interactions are beneficial in meeting the requirement of the adiabatic condition,thereby facilitating the realization of adiabatic atom–molecule conversion.This enhancement of the fulfillment of the adiabatic condition is further evidenced by the stabilization of periodic oscillations in the mean molecule number over time,protected by these interactions,even when the frequency lies within the localized regime.Interestingly,in the diffusive regime,while the many-body interaction has little effect on the dynamical equilibrium of atom–molecule conversion,it significantly expands the diffusive regime.In the high-frequency limit,many-body interactions are found to completely suppress atom–molecule conversion.Our results shed light on how molecule–molecule interactions influence the boundaries between different dynamical regimes.展开更多
The interaction between 1,2,3-triazine and three water molecules was studied using density functional theory B3LYP method at 6-31-t＋＋G^＊＊ basis set. Various structures for 1,2,3-triazine-（water）n （n= 1, 2, 3） ...The interaction between 1,2,3-triazine and three water molecules was studied using density functional theory B3LYP method at 6-31-t＋＋G^＊＊ basis set. Various structures for 1,2,3-triazine-（water）n （n= 1, 2, 3） complex were investigated and the different lower energy structures were reported. Many-body analysis was also carded out to obtain relaxation energy and many-body interaction energy （two, three, and four-body）, and the most stable conformer has the basis set superposition error corrected interaction energy of -- 102.61 kJ/mol. The relaxation energy, two- and three-body interactions have significant contribution to the total interaction energy whereas four-body interaction was very small for 1,2,3-triazine-（water）3 complex.展开更多
An extended electron model fully recovers many of the experimental results of quantum mechanics while it avoids many of the pitfalls and remains generally free of paradoxes. The formulation of the manybody electronic ...An extended electron model fully recovers many of the experimental results of quantum mechanics while it avoids many of the pitfalls and remains generally free of paradoxes. The formulation of the manybody electronic problem here resembles the Kohn Sham formulation of standard density functional theory. However, rather than referring electronic properties to a large set of single electron orbitals, the extended electron model uses only mass density and field components, leading to a substantial increase in computational efficiency. To date, the Hohenberg-Kohn theorems have not been proved for a model of this type, nor has a universal energy functional been presented. In this paper, we address these problems and show that the Hohenberg Kohn theorems do also hold for a density model of this type. We then present a proof^of^concept practical implementation of this method and show that it reproduces the accuracy of more widely used methods on a test-set of small atomic systems, thus paving the way for the development of fast, efficient and accurate codes on this basis.展开更多
基金supported by the Zhejiang Provincial Natural Science Foundation of China(No.LD25A050002)the National Natural Science Foundation of China(No.12375021)the National Key Research and Development Program of China(No.2022YFA1404203).
文摘Quantum many-body systems lie at the heart of modern fundamental physics.The study of these systems has revealed a plethora of fascinating phenomena,such as quantum thermalization,many-body localization,and quantum many-body scars.This review provides a comprehensive overview of the recent advances in understanding quantum many-body scars and non-ergodic dynamics in quantum systems on superconducting-circuit platforms,ranging from theoretical mechanisms and effective models to experimental observations.
基金sponsored by the Youth Talent(team)project of Gansu Province(Grant No.2025QNTD12)the Natural ScienceFoundation of Gansu Province(Grant No.25JRRM001,23JRRM0755).
文摘Based on atomic crystal configurations,we studied many-body interaction properties of face-centered cubic(fcc)solid argon(Ar)within the atomic distance range of 2.0A to 3.6A at T=300 K.The resulting EOS can accurately describe the compression behavior of solid Ar under the experimentally investigated pressure range(0~114GPa).Statistically,903(Ar)2 clusters were identified,corresponding to 12 distinct geometric configurations,861(Ar)3 clusters correspond to 25 distinct geometric configurations,816(Ar)4clusters correspond to 27 distinct geometric configurations,and the calculation results exhibited good convergence.For comparative purposes,the EOS of fcc solid Ar was also calculated using a two-body potential-only approach,which showed excellent agreement with experimental data under relevant pressures.Incorporating three-body terms extended the EOS accuracy to 80 GPa,while the inclusion of four-body terms further improved the precision up to 114 GPa.Higher-order many-body terms are expected to enable accurate interpretation of experimental phenomena in solid Ar above 114 GPa.In addition,when the molar volume is reduced to a fixed value,the zero-point vibration pressure has already reached a certain proportion,then it must be considered and cannot be ignored.This study provides a reliable theoretical model for the study of high-pressure properties and zero-point energy of rare gas solids.
文摘In this paper, we deduce the analytical form of many-body interatomic potentials based on the Green's function in tight-binding representation. The many-body potentials are expressed as the functions of the hopping integrals which are the physical origin of cohesion of atoms. For thesimple case of s-valent system, the inversion of the many-body potentials are discussed in detail by using the lattice inversion method.
文摘Quantum simulation has been developed extensively over the past decades,widely applied to different models to explore dynamics in the quantum regime.Rydberg atoms have strong dipole-dipole interactions and interact with each other over a long distance,which makes it straightforward to build many-body interacting quantum systems to simulate specific models.Additionally,neutral atoms are easily manipulated due to their weak interactions.These advantages make Rydberg many-body system an ideal platform to implement quantum simulations.This paper reviews several quantum simulations for different models based on Rydberg many-body systems,including quantum Ising models in one dimension and two dimensions mainly for quantum magnetism,XY model for excitation transport,SSH model for symmetry-protected topological phases,and critical self-organized behaviors in many-body systems.Besides,some challenges and promising directions of quantum simulations based on Rydberg many-body system are discussed in this paper.
基金supported by the National Basic Research Program of China(Grant No.2012CB922101)the National Natural Science Foundation of China(Grant Nos.11374331 and 11304357)
文摘This article presents an elementary introduction on various aspects of the prototypical integrable model the LiebLiniger Bose gas ranging from the cooperative to the collective features of many-body phenomena. In 1963, Lieb and Liniger first solved this quantum field theory many-body problem using Bethe＇s hypothesis, i.e., a particular form of wavefunction introduced by Bethe in solving the one-dimensional Heisenberg model in 1931. Despite the Lieb-Liniger model is arguably the simplest exactly solvable model, it exhibits rich quantum many-body physics in terms of the aspects of mathematical integrability and physical universality. Moreover, the Yang-Yang grand canonical ensemble description for the model provides us with a deep understanding of quantum statistics, thermodynamics, and quantum critical phenomena at the many-body physical level. Recently, such fundamental physics of this exactly solved model has been attracting growing interest in experiments. Since 2004, there have been more than 20 experimental papers that rbported novel observations of different physical aspects of the Lieb--Liniger model in the laboratory. So far the observed results are in excellent agreement with results obtained using the analysis of this simplest exactly solved model. Those experimental observations reveal the unique beauty of integrability.
文摘The necessary derivation of negative mass in dispersion dynamics suggests cosmic applications. The method analyzes functional relationships between particle angular frequency, wave vector, rest mass and electromagnetic or nuclear potential, f(ω, k, m0, V) = 0. A summary of consequential predictions of the dynamics leads to a calculation of ways in which negative mass might influence such phenomena as the rotational velocities that are observed in spiral galaxies. The velocities are found to be not Newtonian in the simple two body approximations for our solar system;but nearly constant with increasing orbital radii. It has moreover been suggested that the motion is due to halo structures of dark matter or dark energy. However, the motion is simply described by many-body gravitation that is transmitted along elastic spiral arms. In this context, we calculate possible effects of negative mass, but without observational confirmation.
基金Project supported by the Research Foundation for Higher Level Talents of West Anhui University(Grant No.WGKQ2021005)。
文摘Employing the advanced relativistic configuration interaction(RCI)combined with the many-body perturbation theory(RMBPT)method,we report energies and lifetime values for the lowest 35 energy levels from the(1s^(2))nl configurations(where the principal quantum number n=2–6 and the angular quantum number l=0,...,n-1)of lithium-like iron Fe XXIV,as well as complete data on the transition wavelengths,radiative rates,absorption oscillator strengths,and line strengths between the levels.Both the allowed(E1)and forbidden(magnetic dipole M1,magnetic quadrupole M2,and electric quadrupole E2)ones are reported.Through detailed comparisons with previous results,we assess the overall accuracies of present RMBPT results to be likely the most precise ones to date.Configuration interaction effects are found to be very important for the energies and radiative properties for the ion.The present RMBPT results are valuable for spectral line identification,plasma modeling,and diagnosing.
文摘In this paper, an extended spectral theorem is given, which enables one to calculate the correlation functions when complex eigenvalues appear. To do so, a Fourier transformation with a complex argument is utilized. We treat all the Matsbara frequencies, including Fermionic and Bosonic frequencies, on an equal footing. It is pointed out that when complex eigenvalues appear, the dissipation of a system cannot simply be ascribed to the pure imaginary part of the Green function. Therefore, the use of the name fluctuation-dissipation theorem should be careful.
基金Project supported by the National Natural Science Foundation of China(Nos.11872283,12002242,11902188,and 12102218)the Shanghai Science and Technology Talent Program(No.19YF1417400)the China Postdoctoral Science Foundation(No.2020M680525)。
文摘Heat and mass transfer during the process of liquid droplet dynamic behaviors has attracted much attention in decades.At mesoscopic scale,numerical simulations of liquid droplets motion,such as impacting,sliding,and coalescence,have been widely studied by using the particle-based method named many-body dissipative particle dynamics(MDPD).However,the detailed information on heat transfer needs further description.This paper develops a modified MDPD with energy conservation(MDPDE)by introducing a temperature-dependent long-term attractive interaction.By fitting or deriving the expressions of the strength of the attractive force,the exponent of the weight function in the dissipative force,and the mesoscopic heat friction coefficient about temperature,we calculate the viscosity,self-diffusivity,thermal conductivity,and surface tension,and obtain the Schmidt number Sc,the Prandtl number P r,and the Ohnesorge number Oh for 273 K to 373 K.The simulation data of MDPDE coincide well with the experimental data of water,indicating that our model can be used to simulate the dynamic behaviors of liquid water.Furthermore,we compare the equilibrium contact angle of droplets wetting on solid surfaces with that calculated from three interfacial tensions by MDPDE simulations.The coincident results not only stand for the validation of Young’s equation at mesoscale,but manifest the reliability of our MDPDE model and applicability to the cases with free surfaces.Our model can be extended to study the multiphase flow withcomplex heat and mass transfer.
基金supported by the National Natural Science Foundation of China(No.21773297,No.21973108,and No.21921004)supported by the National Natural Science Foundation of China(No.21805258)supported by the National Natural Science Foundation of China(No.21973107)。
文摘Although the many-body expansion(MBE)approach is widely applied to estimate the energy of large systems containing weak interactions,it is inapplicable to calculating the energies of covalent or metal clusters.In this work,we propose an interaction manybody expansion(IMBE)to calculate the energy of atomic clusters containing covalent bonds.In this approach,the energy of a system is expressed as the sum of the energy of atoms and the interaction energy between the atom and its surrounding atoms.The IMBE method is first applied to calculate the energies of nitrogen clusters,in which the interatomic interactions are truncated to four-body terms.The results show that the IMBE approach could significantly reduce the energy error for nitrogen clusters compared with the traditional MBE method.The weak size and structure dependence of the IMBE error with respect to DFT calculations indicates the IMBE method has good potential application in estimating energy of large covalent systems.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 11174228 and 10874132)
文摘We study the charge oscillation in the triangular quantum dots symmetrically coupled to the leads. A strong charge oscillation is observed even for a very small level difference. We attribute this oscillation behaviour to the many- body effect in the strongly correlated system instead of the physical scenarios based on the mean-field approach in the previous works for the two-level dot. The level difference induces the difference of the occupations between different dots, while the symmetry of the many-body states favours the homogeneous distribution of the charge density on the three dots. The interplay of these two factors results in the charge oscillation.
文摘In this paper the tensor probability current and continuity equation is obtained, with this the correlated cross section of many particle scattering can be evaluation.
基金supported by the National Natural Science Foundation of China(Grant Nos.12450004,12274288,12334008,and 12174441)the National Key R&D Program of China(Grant No.2023YFA1406500)the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0301900)。
文摘Investigation of quantum criticality in condensed matter systems not only reveals universal behaviors of quantum phase transitions but also deepens our understanding of emergent physics in quantum many-body systems.With accurate descriptions of the ground states and low-energy excitations of(quasi-)one-dimensional(1D)quantum spin models,significant progress has been made in studying quantum criticality and related emergent physics.In this review,we provide a short survey on some recent developments in this field.We start by discussing critical thermodynamics and dynamics of transverse-field Ising chain,highlighting novel quantum integrability and many-body excitations upon relevant perturbations.Dynamical properties of the excitations are further discussed,along with their experimental verification.Along the line of integrability,we further discuss the Heisenberg-Ising chain,introducing the string magnetic state.Among them,non-trivial string solutions which go beyond conventional field theory,have also been observed in experiments.Apart from the critical phenomena associated with the standard Ginzburg-Landau paradigm,we introduce the deconfined quantum criticality,which arises as a consequence of a continuous phase transition between two ordered states.Such a transition goes beyond the description of the Ginzburg-Landau paradigm and is characterized by the emergence of fractionalized spin excitations and enhanced continuous symmetry at the quantum critical point.Finally,we conclude by highlighting potential novel critical phenomena and emergent physics and their realizations in quasi-1D quantum magnetic systems.
基金supported by the National Key Research and Development Program of China (Grant No. 2021YFA1402002)the National Natural Science Foundation of China (Grant Nos. U21A6006, U21A20433, 92465201,12104277, 12104278, 12474360, and 92265108)+1 种基金the Fund for Shanxi “331 Project” Key Subjectsthe Postdoctoral Fellowship Program of CPSF(Grant No. GZC20240960)
文摘It has been demonstrated that the Rydberg criticality in a many-body atomic system can enhance the measurement sensitivity of the microwave electric field by increasing the Fisher information.In our previous work,we proposed and experimentally verified that the Fisher information near the critical point can be increased by more than two orders of magnitude with the Rydberg atoms coupled with an optical cavity compared with that in free space.Here we demonstrate the precision measurement of the microwave electric field by cavity-enhanced critical behavior.We show that the equivalent measurement sensitivity of the microwave electric field can be enhanced by an order of magnitude compared with that in free space.The obtained sensitivity can be enhanced to 2.6 nV cm^(−1) Hz^(−1/2).
基金supported in part by the National Natural Science Foundation of China(12347107 and 12334003)the MOSTC(2021YFA1400100)+15 种基金the New Cornerstone Science Foundation through the Xplorer Prizesupported by the Postdoctoral Fellowship ProgramChina Postdoctoral Science Foundation(BX20250169)the support from Innovation Program for Quantum Science and Technology(2024ZD0301700)the start-up grant at IOP-CASsupported by the National Natural Science Foundation of China(12075324 and 12222515)the Science and Technology Projects in Guangdong Province(2021QN02X561)supported by the Gordon and Betty Moore Foundation(GBMF8685)toward the Princeton Theory Programthe Gordon and Betty Moore Foundation’s EPiQS Initiative(GBMF11070)the Office of Naval Research(N00014-20–12303)the Global Collaborative Network Grant at Princeton Universitythe Simons Investigator Grant(404513)the BSF Israel US foundation(2018226)the NSF-MERSEC(MERSEC DMR 2011750)the Simons Collaboration on New Frontiers in Superconductivitythe Schmidt Foundation at the Princeton University。
文摘Non-equilibrium dynamics of quantum many-body systems has attracted increasing attention owing to a variety of intriguing phenomena absent in equilibrium physics.A prominent example is the quantum Mpemba effect,where subsystem symmetry is restored more rapidly under a symmetric quench from a more asymmetric initial state.In this work,we investigate symmetry restoration and the quantum Mpemba effect in many-body localized systems for a range of initial states.We show that symmetry can still be restored in the many-body localization regime without approaching thermal equilibrium.Moreover,we demonstrate that the quantum Mpemba effect emerges universally for any tilted product state,in contrast to chaotic systems where its occurrence depends sensitively on the choice of the initial state.We further provide a theoretical analysis of symmetry restoration and the quantum Mpemba effect using an effective model for many-body localization.Overall,this paper fills an important gap in establishing a unified understanding of symmetry restoration and the quantum Mpemba effect in generic many-body systems,and it advances our understanding of many-body localization.
基金supported by Beijing Institute of Technology Research Fund Program for Young Scholarspartially supported by Tianyan Quantum Computing Program.
文摘Variational quantum algorithms have been widely demonstrated in both experimental and theoretical contexts to have extensive applications in quantum simulation,optimization,and machine learning.However,the exponential growth in the dimension of the Hilbert space results in the phenomenon of vanishing parameter gradients in the circuit as the number of qubits and circuit depth increase,known as the barren plateau phenomena.In recent years,research in non-equilibrium statistical physics has led to the discovery of the realization of many-body localization.As a type of floquet system,many-body localized floquet system has phase avoiding thermalization with an extensive parameter space coverage and has been experimentally demonstrated can produce time crystals.We applied this circuit to the variational quantum algorithms for the calculation of many-body ground states and studied the variance of gradient for parameter updates under this circuit.We found that this circuit structure can effectively avoid barren plateaus.We also analyzed the entropy growth,information scrambling,and optimizer dynamics of this circuit.Leveraging this characteristic,we designed a new type of variational ansatz,called the“many-body localization ansatz”.We applied it to solve quantum many-body ground states and examined its circuit properties.Our numerical results show that our ansatz significantly improved the variational quantum algorithm.
文摘Hilbert space fragmentation(HSF)is a mechanism for generating quantum many-body scar(QMBS),which provides a route to weakly break ergodicity.Many scarred systems possess an exponentially large number of zeroenergy states due to the chiral symmetry induced bipartition of the Hilbert space.In this work,we study the QMBS phenomenology under the interplay between the chiral symmetry and pseudo HSF,where the Hilbert space is approximately fragmented into different blocks.We consider a model of tilted chain of interacting spinless fermions with periodically varying tunneling strength.At small tunneling strength,we analytically derive the resonance conditions under which the system is described by an effective model with chiral symmetry and pseudo HSF.We find that the interplay between the two gives rise to a highly localized zero-energy QMBS when the particle number is even.This zero-energy QMBS induces an unusual scarred dynamical phenomenon.Specifically,the fidelity from a simple initial state oscillates around a finite fixed value without decaying,instead of showing the typical decaying collapse and revival observed when the particle number is odd and in common scarred systems.We show that the signature of the unusual scarred dynamical behaviour can also be detected in the original driven system by measuring local observables.Our findings enrich the scar phenomenon and deepen the understanding of the relation between Hilbert space structure and QMBS.
基金supported by the National Natural Science Foundation of China(NSFC)(Grant Nos.12375019 and 11974273)Shanxi Agricultural University Introduction of Talent Research Start-up Project Grant(Grant No.2024BQ11)the Research Funding and Reward for Doctoral Graduates Researchers Coming to Work in Shanxi Province(Grant No.SXBYKY2024050).
文摘We investigate the quantum many-body dynamics of ultracold atom–molecule conversion using a Floquet spin-boson model,where the periodic energy detuning between molecules and atomic pairs is utilized to explore various dynamical regimes.We find that the upper bound of the adiabatic driving frequency increases continuously with the strength of molecule–molecule interactions,indicating that many-body interactions are beneficial in meeting the requirement of the adiabatic condition,thereby facilitating the realization of adiabatic atom–molecule conversion.This enhancement of the fulfillment of the adiabatic condition is further evidenced by the stabilization of periodic oscillations in the mean molecule number over time,protected by these interactions,even when the frequency lies within the localized regime.Interestingly,in the diffusive regime,while the many-body interaction has little effect on the dynamical equilibrium of atom–molecule conversion,it significantly expands the diffusive regime.In the high-frequency limit,many-body interactions are found to completely suppress atom–molecule conversion.Our results shed light on how molecule–molecule interactions influence the boundaries between different dynamical regimes.
基金Project supported by the Sichuan Province Youth Foundation （No. 05ZQ026-054） and the Natural Science Foundation ot the Education Department of Sichuan Province.
文摘The interaction between 1,2,3-triazine and three water molecules was studied using density functional theory B3LYP method at 6-31-t＋＋G^＊＊ basis set. Various structures for 1,2,3-triazine-（water）n （n= 1, 2, 3） complex were investigated and the different lower energy structures were reported. Many-body analysis was also carded out to obtain relaxation energy and many-body interaction energy （two, three, and four-body）, and the most stable conformer has the basis set superposition error corrected interaction energy of -- 102.61 kJ/mol. The relaxation energy, two- and three-body interactions have significant contribution to the total interaction energy whereas four-body interaction was very small for 1,2,3-triazine-（water）3 complex.
文摘An extended electron model fully recovers many of the experimental results of quantum mechanics while it avoids many of the pitfalls and remains generally free of paradoxes. The formulation of the manybody electronic problem here resembles the Kohn Sham formulation of standard density functional theory. However, rather than referring electronic properties to a large set of single electron orbitals, the extended electron model uses only mass density and field components, leading to a substantial increase in computational efficiency. To date, the Hohenberg-Kohn theorems have not been proved for a model of this type, nor has a universal energy functional been presented. In this paper, we address these problems and show that the Hohenberg Kohn theorems do also hold for a density model of this type. We then present a proof^of^concept practical implementation of this method and show that it reproduces the accuracy of more widely used methods on a test-set of small atomic systems, thus paving the way for the development of fast, efficient and accurate codes on this basis.
