The cosmological constant problem arises because the magnitude of vacuum energy density predicted by the Quantum Field Theory is about 120 orders of magnitude larger then the value implied by cosmological observations...The cosmological constant problem arises because the magnitude of vacuum energy density predicted by the Quantum Field Theory is about 120 orders of magnitude larger then the value implied by cosmological observations of accelerating cosmic expansion. We pointed out that the fractal nature of the quantum space-time with negative Hausdorff-Colombeau dimensions can resolve this tension. The canonical Quantum Field Theory is widely believed to break down at some fundamental high-energy cutoff and therefore the quantum fluctuations in the vacuum can be treated classically seriously only up to this high-energy cutoff. In this paper we argue that the Quantum Field Theory in fractal space-time with negative Hausdorff-Colombeau dimensions gives high-energy cutoff on natural way. We argue that there exists hidden physical mechanism which cancels divergences in canonical QED4, QCD4, Higher-Derivative-Quantum gravity, etc. In fact we argue that corresponding supermassive Pauli-Villars ghost fields really exist. It means that there exists the ghost-driven acceleration of the universe hidden in cosmological constant. In order to obtain the desired physical result we apply the canonical Pauli-Villars regularization up to Λ*. This would fit in the observed value of the dark energy needed to explain the accelerated expansion of the universe if we choose highly symmetric masses distribution between standard matter and ghost matter below the scale Λ*, i.e., The small value of the cosmological constant is explained by tiny violation of the symmetry between standard matter and ghost matter. Dark matter nature is also explained using a common origin of the dark energy and dark matter phenomena.展开更多
We investigate the intensity correlation function C（s） and its associated relaxation time Tc for a saturation model of single-mode laser with correlated noises. The expressions of O（s） and Tc are derived by means ...We investigate the intensity correlation function C（s） and its associated relaxation time Tc for a saturation model of single-mode laser with correlated noises. The expressions of O（s） and Tc are derived by means of the projection operator method, and effects of correlations between an additive noise and a multiplicative noise are discussed by numerical calculation. Based on the calculated results, it is found that the correlation strength A between the additive noise and the multiplicative noise can enhance the fluctuation decay of the laser intensity.展开更多
Currently, people investigating the magnetic properties of ferromagnets at low temperatures have found that there exists a class of magnetic alloys such as SmCo<sub>3.5</sub>Cu<sub>1.5</sub>, S...Currently, people investigating the magnetic properties of ferromagnets at low temperatures have found that there exists a class of magnetic alloys such as SmCo<sub>3.5</sub>Cu<sub>1.5</sub>, Sm（CoCuFeTi）<sub>6.8</sub>, Tb(Fe<sub>0.7</sub>Al<sub>0.3</sub>)<sub>2</sub>, Dy(Fe<sub>0.9</sub>Ga<sub>0.1</sub>)<sub>2</sub>, of which the curves of coercive force H<sub>c</sub> versus temperature T are logarithmic shapes at high temperatures and ap-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
The ferroelectric transitions of several SrTiO3-based ferroelectrics are investigated experimentally and theoretically, with special attention to the critical scaling exponents associated with the phase transitions, i...The ferroelectric transitions of several SrTiO3-based ferroelectrics are investigated experimentally and theoretically, with special attention to the critical scaling exponents associated with the phase transitions, in order to understand the competition among quantum fluctuations （QFs）, quenched disorder, and ferroelectric ordering. Two representative systems with sufficiently strong QFs and quenched disorders in competition with the ferroelectric ordering are investigated. We start from non-stoichiometric SrTiO3（STO） with the Sr/Ti ratio deviating slightly from one, which is believed to maintain strong QFs. Then, we address Ba/Ca co-doped Sr1-x（Ca0.6389Ba0.3611）xTiO3（SCBT） with the averaged Sr-site ionic radius identical to the Sr2＋ ionic radius, which is believed to offer remarkable quenched disorder associated with the Sr-site ionic mismatch. The critical exponents associated with polarization P and dielectric susceptibility ε, respectively, as functions of temperature T close to the critical point Tc, are evaluated. It is revealed that both non-stoichiometric SrTiO3 and SCBT exhibit much bigger critical exponents than the Landau mean-field theory predictions. These critical exponents then decrease gradually with increasing doping level or deviation of Sr/Ti ratio from one. A transverse Ising model applicable to the Sr-site doped STO （e.g., Sr1-xCaxTiO3） at low level is used to explain the observed experimental data. It is suggested that the serious deviation of these critical exponents from the Landau theory predictions in these STO-based systems is ascribed to the significant QFs and quenched disorder by partially suppressing the long-range spatial correlation of electric dipoles around the transitions. The present work thus sheds light on our understanding of the critical behaviors of ferroelectric transitions in STO in the presence of quantum fluctuations and quenched disorder, whose effects have been demonstrated to be remarkable.展开更多
This paper stuides the magnetization and quantum fluctuations of an antiferro-antiferromagnetic （AF-AF） doublelayer at zero temperature. It is found that the exchanges and anisotropy constants affect the quantum flu...This paper stuides the magnetization and quantum fluctuations of an antiferro-antiferromagnetic （AF-AF） doublelayer at zero temperature. It is found that the exchanges and anisotropy constants affect the quantum fluctuations of spins. If the anisotropy exists, there will be no acoustic energy branch in the system. The anisotropy constant, antiferromagnetic intralayer and interlayer coupling have important roles in a balance of the quantum competition.展开更多
Considering the quantum fluctuation effects,the existence and stability of solitons in a Bose-Einstein condensate subjected in a PT-symmetric potential are discussed.Using the variational approach,we investigate how t...Considering the quantum fluctuation effects,the existence and stability of solitons in a Bose-Einstein condensate subjected in a PT-symmetric potential are discussed.Using the variational approach,we investigate how the quantum fluctuation affects the self-localization and stability of the condensate with attractive two-body interactions.The results show that the quantum fluctuation dramatically influences the shape,width,and chemical potential of the condensate.Analytical variational computation also predicts there exists a positive critical quantum fluctuation strength qc with each fixed attractive two-body interaction g0,if the quantum fluctuation strength q0 is bigger than qc,there is no bright soliton solution existence.We also study the effects of the quantum fluctuations on the stability of solitons using the Vakhitov-Kolokolov(VK)stability criterion.A robust stable bright soliton will always exist when the quantum fluctuation strength q0 belongs to the parameter regimes qc≥q0>0.展开更多
A novel method to determine the density and temperature of a system constituted by fermions and/or bosons is proposed based on quantum fluctuations.For fermions system,the results in the limit where the reached temper...A novel method to determine the density and temperature of a system constituted by fermions and/or bosons is proposed based on quantum fluctuations.For fermions system,the results in the limit where the reached temperature T is small and where there is no constraint for the reached temperature T compared to the Fermi energy εf at a given density ρ are given,respectively.Quadrupole and multiplicity fluctuation relations are derived in terms of T/εf.We compared the two set results in the limit when T is much smaller compared to Fermi energy εf and they are consistent,as expected.The classical limit is also obtained for high temperatures and low densities.For bosons system,quadrupole and multiplicity fluctuations using Landau's theory of fluctuations near the critical point for a Bose-Einstein condensate(BEC) at a given density ρ are derived.As an example,we apply our approach to heavy ion collisions using the Constrained Molecular Dynamics model(CoMD) which includes the fermionic statistics.The multiplicity fluctuation quenching for fermions is found in the model and confirmed by experimental data.To reproduce the available experimental data better,we propose a modification of the collision term in the approach to include the possibility of α-α collisions.The relevant Bose-Einstein factor in the collision term is properly taken into account.This approach increases the yields of bosons relative to fermions closer to data.Boson fluctuations become larger than one as expected.展开更多
文摘The cosmological constant problem arises because the magnitude of vacuum energy density predicted by the Quantum Field Theory is about 120 orders of magnitude larger then the value implied by cosmological observations of accelerating cosmic expansion. We pointed out that the fractal nature of the quantum space-time with negative Hausdorff-Colombeau dimensions can resolve this tension. The canonical Quantum Field Theory is widely believed to break down at some fundamental high-energy cutoff and therefore the quantum fluctuations in the vacuum can be treated classically seriously only up to this high-energy cutoff. In this paper we argue that the Quantum Field Theory in fractal space-time with negative Hausdorff-Colombeau dimensions gives high-energy cutoff on natural way. We argue that there exists hidden physical mechanism which cancels divergences in canonical QED4, QCD4, Higher-Derivative-Quantum gravity, etc. In fact we argue that corresponding supermassive Pauli-Villars ghost fields really exist. It means that there exists the ghost-driven acceleration of the universe hidden in cosmological constant. In order to obtain the desired physical result we apply the canonical Pauli-Villars regularization up to Λ*. This would fit in the observed value of the dark energy needed to explain the accelerated expansion of the universe if we choose highly symmetric masses distribution between standard matter and ghost matter below the scale Λ*, i.e., The small value of the cosmological constant is explained by tiny violation of the symmetry between standard matter and ghost matter. Dark matter nature is also explained using a common origin of the dark energy and dark matter phenomena.
基金Supported by the National Natural Science Foundation of China under Grant No 10363001.
文摘We investigate the intensity correlation function C（s） and its associated relaxation time Tc for a saturation model of single-mode laser with correlated noises. The expressions of O（s） and Tc are derived by means of the projection operator method, and effects of correlations between an additive noise and a multiplicative noise are discussed by numerical calculation. Based on the calculated results, it is found that the correlation strength A between the additive noise and the multiplicative noise can enhance the fluctuation decay of the laser intensity.
基金Project supported by the National Natural Science Foundation of China
文摘Currently, people investigating the magnetic properties of ferromagnets at low temperatures have found that there exists a class of magnetic alloys such as SmCo<sub>3.5</sub>Cu<sub>1.5</sub>, Sm（CoCuFeTi）<sub>6.8</sub>, Tb(Fe<sub>0.7</sub>Al<sub>0.3</sub>)<sub>2</sub>, Dy(Fe<sub>0.9</sub>Ga<sub>0.1</sub>)<sub>2</sub>, of which the curves of coercive force H<sub>c</sub> versus temperature T are logarithmic shapes at high temperatures and ap-
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.
基金the National Basic Research Program of China(Grant Nos.2011CB922101 and 2009CB623303)the National Natural Science Foundation of China(Grant Nos.11234005 and 11074113)the Priority Academic Development Program of Jiangsu Higher Education Institutions,China
文摘The ferroelectric transitions of several SrTiO3-based ferroelectrics are investigated experimentally and theoretically, with special attention to the critical scaling exponents associated with the phase transitions, in order to understand the competition among quantum fluctuations （QFs）, quenched disorder, and ferroelectric ordering. Two representative systems with sufficiently strong QFs and quenched disorders in competition with the ferroelectric ordering are investigated. We start from non-stoichiometric SrTiO3（STO） with the Sr/Ti ratio deviating slightly from one, which is believed to maintain strong QFs. Then, we address Ba/Ca co-doped Sr1-x（Ca0.6389Ba0.3611）xTiO3（SCBT） with the averaged Sr-site ionic radius identical to the Sr2＋ ionic radius, which is believed to offer remarkable quenched disorder associated with the Sr-site ionic mismatch. The critical exponents associated with polarization P and dielectric susceptibility ε, respectively, as functions of temperature T close to the critical point Tc, are evaluated. It is revealed that both non-stoichiometric SrTiO3 and SCBT exhibit much bigger critical exponents than the Landau mean-field theory predictions. These critical exponents then decrease gradually with increasing doping level or deviation of Sr/Ti ratio from one. A transverse Ising model applicable to the Sr-site doped STO （e.g., Sr1-xCaxTiO3） at low level is used to explain the observed experimental data. It is suggested that the serious deviation of these critical exponents from the Landau theory predictions in these STO-based systems is ascribed to the significant QFs and quenched disorder by partially suppressing the long-range spatial correlation of electric dipoles around the transitions. The present work thus sheds light on our understanding of the critical behaviors of ferroelectric transitions in STO in the presence of quantum fluctuations and quenched disorder, whose effects have been demonstrated to be remarkable.
基金supported by the Natural Science Foundation of the Educational Department of Liaoning Province,China (Grant Nos20060638 and 2008533)
文摘This paper stuides the magnetization and quantum fluctuations of an antiferro-antiferromagnetic （AF-AF） doublelayer at zero temperature. It is found that the exchanges and anisotropy constants affect the quantum fluctuations of spins. If the anisotropy exists, there will be no acoustic energy branch in the system. The anisotropy constant, antiferromagnetic intralayer and interlayer coupling have important roles in a balance of the quantum competition.
基金Supported by the National Natural Science Foundation of China under Grant Nos.11647017,11805116,21703166supported by Science Research Fund of Shaanxi University of Science and Technology under Grant No.BJ16-03
文摘Considering the quantum fluctuation effects,the existence and stability of solitons in a Bose-Einstein condensate subjected in a PT-symmetric potential are discussed.Using the variational approach,we investigate how the quantum fluctuation affects the self-localization and stability of the condensate with attractive two-body interactions.The results show that the quantum fluctuation dramatically influences the shape,width,and chemical potential of the condensate.Analytical variational computation also predicts there exists a positive critical quantum fluctuation strength qc with each fixed attractive two-body interaction g0,if the quantum fluctuation strength q0 is bigger than qc,there is no bright soliton solution existence.We also study the effects of the quantum fluctuations on the stability of solitons using the Vakhitov-Kolokolov(VK)stability criterion.A robust stable bright soliton will always exist when the quantum fluctuation strength q0 belongs to the parameter regimes qc≥q0>0.
文摘A novel method to determine the density and temperature of a system constituted by fermions and/or bosons is proposed based on quantum fluctuations.For fermions system,the results in the limit where the reached temperature T is small and where there is no constraint for the reached temperature T compared to the Fermi energy εf at a given density ρ are given,respectively.Quadrupole and multiplicity fluctuation relations are derived in terms of T/εf.We compared the two set results in the limit when T is much smaller compared to Fermi energy εf and they are consistent,as expected.The classical limit is also obtained for high temperatures and low densities.For bosons system,quadrupole and multiplicity fluctuations using Landau's theory of fluctuations near the critical point for a Bose-Einstein condensate(BEC) at a given density ρ are derived.As an example,we apply our approach to heavy ion collisions using the Constrained Molecular Dynamics model(CoMD) which includes the fermionic statistics.The multiplicity fluctuation quenching for fermions is found in the model and confirmed by experimental data.To reproduce the available experimental data better,we propose a modification of the collision term in the approach to include the possibility of α-α collisions.The relevant Bose-Einstein factor in the collision term is properly taken into account.This approach increases the yields of bosons relative to fermions closer to data.Boson fluctuations become larger than one as expected.
