Feynman’s path integral reformulates the quantum Schrödinger differential equation to be an integral equation.It has been being widely used to compute internuclear quantum-statistical effects on many-body molecu...Feynman’s path integral reformulates the quantum Schrödinger differential equation to be an integral equation.It has been being widely used to compute internuclear quantum-statistical effects on many-body molecular systems.In this Review,the molecular Schrödinger equation will first be introduced,together with the BornOppenheimer approximation that decouples electronic and internuclear motions.Some effective semiclassical potentials,e.g.,centroid potential,which are all formulated in terms of Feynman’s path integral,will be discussed and compared.These semiclassical potentials can be used to directly calculate the quantum canonical partition function without individual Schrödinger’s energy eigenvalues.As a result,path integrations are conventionally performed with Monte Carlo and molecular dynamics sampling techniques.To complement these techniques,we will examine how Kleinert’s variational perturbation(KP)theory can provide a complete theoretical foundation for developing non-sampling/non-stochastic methods to systematically calculate centroid potential.To enable the powerful KP theory to be practical for many-body molecular systems,we have proposed a new path-integral method:automated integrationfree path-integral(AIF-PI)method.Due to the integration-free and computationally inexpensive characteristics of our AIF-PI method,we have used it to perform ab initio path-integral calculations of kinetic isotope effects on proton-transfer and RNA-related phosphoryl-transfer chemical reactions.The computational procedure of using our AIF-PI method,along with the features of our new centroid path-integral theory at the minimum of the absolute-zero energy(AMAZE),are also highlighted in this review.展开更多
Quantum computers promise to solve finite-temperature properties of quantum many-body systems,which is generally challenging for classical computers due to high computational complexities.Here,we report experimental p...Quantum computers promise to solve finite-temperature properties of quantum many-body systems,which is generally challenging for classical computers due to high computational complexities.Here,we report experimental preparations of Gibbs states and excited states of Heisenberg X X and X X Z models by using a 5-qubit programmable superconducting processor.In the experiments,we apply a hybrid quantum–classical algorithm to generate finite temperature states with classical probability models and variational quantum circuits.We reveal that the Hamiltonians can be fully diagonalized with optimized quantum circuits,which enable us to prepare excited states at arbitrary energy density.We demonstrate that the approach has a self-verifying feature and can estimate fundamental thermal observables with a small statistical error.Based on numerical results,we further show that the time complexity of our approach scales polynomially in the number of qubits,revealing its potential in solving large-scale problems.展开更多
Recent experiments have demonstrated the realization of the three-dimensional quantum Hall effect in highly anisotropic crystalline materials, such as ZrTe|_5 and BaMnSb_2. Such a system supports chiral surface states...Recent experiments have demonstrated the realization of the three-dimensional quantum Hall effect in highly anisotropic crystalline materials, such as ZrTe|_5 and BaMnSb_2. Such a system supports chiral surface states in the presence of a strong magnetic field, which exhibit a one-dimensional metal-insulator crossover due to suppression of surface diffusion by disorder potential. We study the nontrivial surface states in a lattice model and find a wide crossover of the level-spacing distribution through a semi-Poisson distribution. We also discover a nonmonotonic evolution of the level statistics due to the disorder-induced mixture of surface and bulk states.展开更多
With hydrogen-like impurity(HLI) located in the center of Cs I quantum pseudodot(QPD) and by using the variational method of Pekar type(VMPT), we investigate the first-excited state energy(FESE), excitation en...With hydrogen-like impurity(HLI) located in the center of Cs I quantum pseudodot(QPD) and by using the variational method of Pekar type(VMPT), we investigate the first-excited state energy(FESE), excitation energy and transition frequency of the strongly-coupled bound polaron in the present paper. Temperature effects on bound polaron properties are calculated by employing the quantum statistical theory(QST). According to the present work's numerical results, the FESE, excitation energy and transition frequency decay(amplify) with raising temperature in the regime of lower(higher)temperature. They are decreasing functions of Coulomb impurity potential strength.展开更多
In weak measurement thought experiment, an ensemble consists of M quantum particles and N states. We observe that separability of the particles is lost, and hence we have fuzzy occupation numbers for the particles in ...In weak measurement thought experiment, an ensemble consists of M quantum particles and N states. We observe that separability of the particles is lost, and hence we have fuzzy occupation numbers for the particles in the ensemble. Without sharply measuring each particle state, quantum interferences add extra possible configurations of the ensemble, this explains the Quantum Pigeonhole Principle. This principle adds more entropy to the system;hence the particles seem to have a new kind of correlations emergent from particles not having a single, well-defined state. We formulated the Quantum Pigeonhole Principle in the language of abstract Hilbert spaces, then generalized it to systems consisting of mixed states. This insight into the fundamentals of quantum statistical mechanics could help us understand the interpretation of quantum mechanics more deeply, and possibly have implication on quantum computing and information theory.展开更多
In contrast to interferometry-based quantum sensing,where interparticle interaction is detrimental,quantum many-body probes exploit such interactions to achieve quantum-enhanced sensitivity.In most of the studied quan...In contrast to interferometry-based quantum sensing,where interparticle interaction is detrimental,quantum many-body probes exploit such interactions to achieve quantum-enhanced sensitivity.In most of the studied quantum many-body probes,the interaction is considered to be short-ranged.Here,we investigate the impact of long-range interaction at various filling factors on the performance of Stark quantum probes for measuring a small gradient field.These probes harness the ground state Stark localization phase transition which happens at an infinitesimal gradient field as the system size increases.Our results show that while super-Heisenberg precision is always achievable in all ranges of interaction,the long-range interacting Stark probe reveals two distinct behaviors.First,by algebraically increasing the range of interaction,the localization power is enhanced and thus the sensitivity of the probe decreases.Second,as the interaction range becomes close to a fully connected graph its effective localization power disappears and thus the sensitivity of the probe starts to enhance again.The super-Heisenberg precision is achievable throughout the extended phase until the transition point and remains valid even when the state preparation time is incorporated in the resource analysis.As the probe enters the localized phase,the sensitivity decreases and its performance becomes size-independent,following a universal behavior.In addition,our analysis shows that lower filling factors lead to better precision for measuring weak gradient fields.展开更多
This document will from first principles delineate the degree of flatness, or deviations from, in early universe models. We will, afterwards, make comparison with recent results we have looked at concerning metric ten...This document will from first principles delineate the degree of flatness, or deviations from, in early universe models. We will, afterwards, make comparison with recent results we have looked at concerning metric tensor fluctuations and comment upon the role of what early universe gravitational energy may play a role in the presumed deviation from flat space results. Note that N~S<sub>initial(graviton)</sub>~10<sup>37 </sup>will be tied into the presumed results for initial state density, in ways we will comment upon, leading to observations which are supporting the physics given by Equation (26) of this document as with regards to Gravitational waves, from relic conditions. The deviations from flat space may help confirm the conclusions given by Buchert, Carfora, Kolb, and Wiltshire allegedly refuting the claim by Green and Wald that “the standard FLRW model approximates our Universe extremely well on all scales, except close to strong field astrophysical objects”, as well as give additional analysis appropriate for adding detail to expanding experimental procedures for investigating non FLRW models such as the Polynomial Inflation models as given by Kobayashi, and Seto, as well as other nonstandard cosmologies, as brought up by Corda, and other researchers. As well as improve upon post Bicep 2 measurements which will avoid GW signatures from interstellar dust, as opposed to relic GW. We hope that our approach may help in the differentiation between different cosmology models. Most importantly, our procedure may help, with refinement of admissible frequency range, avoid the problem of BICEP 2, which had its presumed GW signals from presumed relic conditions identical to dust induced frequencies, as so identified by the Planck collaboration in reference [25] which we comment upon in the conclusion.展开更多
Based on the quantum Vlasov equation, the effect of frequency chirp on electron-positron pair production is investigated. The cycle parameter, which characterizes the laser field cycle degree within the pulse, is also...Based on the quantum Vlasov equation, the effect of frequency chirp on electron-positron pair production is investigated. The cycle parameter, which characterizes the laser field cycle degree within the pulse, is also considered. In both supercycle and subcycle laser pulses the frequency chirp can greatly enhance the momentum distribution function of created pairs and the pair number density. The pair number density created by a supercycle laser pulse is larger than that by a subcycle pulse under the same laser frequency and chirping. There exists an optimal cycle parameter corresponding to the maximum value of the created pair number density for different chirp rates. It is found that the pair number density is sensitive/insensitive to chirping rate when the cycle parameter lies below/above the optimal one.展开更多
By using the entanglement entropy method, this paper calculates the statistical entropy of the Bose and Fermi fields in thin films, and derives the Bekenstein-Hawking entropy and its correction term on the background ...By using the entanglement entropy method, this paper calculates the statistical entropy of the Bose and Fermi fields in thin films, and derives the Bekenstein-Hawking entropy and its correction term on the background of a rotating and charged black string. Here, the quantum field is entangled with quantum states in the black string and thin film to the event horizon from outside the rotating and charged black string. Taking into account the effect of the generalized uncertainty principle on quantum state density, it removes the difficulty of the divergence of state density near the event horizon in the brick-wall model. These calculations and discussions imply that high density quantum states near the event horizon of a black string are strongly correlated with the quantum states in a black string and that black string entropy is a quantum effect. The ultraviolet cut-off in the brick-wall model is not reasonable. The generalized uncertainty principle should be considered in the high energy quantum field near the event horizon. From the viewpoint of quantum statistical mechanics, the correction value of Bekenstein-Hawking entropy is obtained. This allows the fundamental recognition of the correction value of black string entropy at nonspherical coordinates.展开更多
We look at what may occur if Boltzmann equations, as presented by Murayama in 2007, Les Houches, are applied to graviton density in a pre-Planckian universe setting. Two restrictions are in order. First of all, we are...We look at what may occur if Boltzmann equations, as presented by Murayama in 2007, Les Houches, are applied to graviton density in a pre-Planckian universe setting. Two restrictions are in order. First of all, we are assuming a graviton mass on the order of 10?62 grams, as if the pre-Planckian regime does not change the nature of Graviton mass, in its low end. Secondly, we are also assuming that a comparatively low temperature regime (far below the Planckian temperature) exists. Finally we are leaving unsaid what may happen if Gravitational waves enter the Planck regime of ultra-high temperature. With those three considerations, we proceed to examine a Graviton density value resulting from perturbation from low to higher temperatures. In the end an ultra- hot Pre big bang cosmology will yield essentially no early universe information transfer crossovers to our present cosmological system. This is not affected by the choice if we have a single repeating universe, or a multiverse. A cold pre inflationary state yields a very different situation. Initial frequencies of Gravitons, though, as outlined may be different in the multiverse case, as opposed to the single repeating universe case. We close with comments as to Bicep 2, and how this document has material as to how to avoid the BICEP 2 disaster. And about choosing between either the possibility of massless Scalar-Tensor Gravity as the correct theory of gravitation or conventional GR.展开更多
We initially look at a nonsingular universe representation of entropy, based in part on what is brought up by Muller and Lousto. This is a gateway to bring up information and computational steps (as defined by Seth Ll...We initially look at a nonsingular universe representation of entropy, based in part on what is brought up by Muller and Lousto. This is a gateway to bring up information and computational steps (as defined by Seth Lloyd) as to what will be available initially due to a modified Zero Point Energy formalism. The Zero Point Energy formalism is modified as due to Vissers’s setting of an angular plane number in early universe cosmology as k(maximum) ~ 1/(Planck length), with a specific initial density giving rise to initial information content which may permit fixing the initial Planck’s constant, h, which is pivotal to the setting of physical law. This will be in the spirit of Stoica’s removal of initial conditions of non-pathological initial starting points in Cosmology. What we want are necessary and sufficient conditions so h(today) = h(initial). We also in addition make a brief survey into 5th force arguments in gravity which also has a strict entropy interpretation. i.e., how to link gravity, quantum mechanics, and E and M through entropy production.展开更多
Using the divergence term appearing in the Lagrangian of the teleparallel equivalent of general relativity (TEGR), we calculate the thermodynamic quantities of four tetrads' spacetime reproducing Lense-Thirring (L...Using the divergence term appearing in the Lagrangian of the teleparallel equivalent of general relativity (TEGR), we calculate the thermodynamic quantities of four tetrads' spacetime reproducing Lense-Thirring (LT) metric. We also investigate the first law of thermodynamics and the quantum statistical relation.展开更多
As a very simple model,the Ising model plays an important role in statistical physics.In the paper,with the help of quantum Liouvillian statistical theory,we study the one-dimensional nonHermitian Ising model at finit...As a very simple model,the Ising model plays an important role in statistical physics.In the paper,with the help of quantum Liouvillian statistical theory,we study the one-dimensional nonHermitian Ising model at finite temperature and give its analytical solutions.We find that the nonHermitian Ising model shows quite different properties from those of its Hermitian counterpart.For example,the‘pseudo-phase transition’is explored between the‘topological’phase and the‘nontopological’phase,at which the Liouvillian energy gap is closed rather than the usual energy gap.In particular,we point out that the one-dimensional non-Hermitian Ising model at finite temperature can be equivalent to an effective anisotropic XY model in the transverse field.This work will help people understand quantum statistical properties of non-Hermitian systems at finite temperatures.展开更多
Recently an f -deformed Fock space which is spanned by | n λ was introduced. These bases are the eigenstates of a deformed non-Hermitian Hamiltonian. In this contribution, we will use rather new nonorthogonal basis ...Recently an f -deformed Fock space which is spanned by | n λ was introduced. These bases are the eigenstates of a deformed non-Hermitian Hamiltonian. In this contribution, we will use rather new nonorthogonal basis vectors for the construction of coherent and squeezed states, which in special case lead to the earlier known states. For this purpose, we first generalize the previously introduced Fock space spanned by | n λ bases, to a new one, spanned by extended two-parameters bases | n λ 1 ,λ 2 . These bases are now the eigenstates of a non-Hermitian Hamiltonian H λ 1 ,λ 2 = a λ 1 ,λ 2 a + 1 2 , where a λ 1 ,λ 2 = a + λ 1 a + λ 2 and a are, respectively, the deformed creation and ordinary bosonic annihilation operators. The bases | n λ 1 ,λ 2 are nonorthogonal (squeezed states), but normalizable. Then, we deduce the new representations of coherent and squeezed states in our two-parameter Fock space. Finally, we discuss the quantum statistical properties, as well as the non-classical properties of the obtained states numerically.展开更多
The study of the polaron of an open quantum system plays an important role in verifying the effectiveness of an approximate many-body theory and predicting novel quantum phenomena in open quantum systems. In a pioneer...The study of the polaron of an open quantum system plays an important role in verifying the effectiveness of an approximate many-body theory and predicting novel quantum phenomena in open quantum systems. In a pioneering work, Piazza et al.(2021) proposed a Fermi-polaron scheme with a lossy impurity, which exhibits a novel long-lived attractive polaron branch in the quantum Zeno limit. However, we have encountered a counterpart problem in which an impurity interacting with an open quantum bath scatters exciting polarons, which is what we focus on. In this work, we determine through analytical research the molecular state under the two limits of vanishingly small and infinitely large dissipation intensities as well as the reason why the dissipation range leads to a decrease in the gap between the molecular state and the molecule-hole continuum in the former case.The spectrum functions of molecular and polaron states with different dissipation ranges and loss rates are investigated. We find the spectral signals of molecular and polaron states will first diffuse and then revive as the dissipation increases. Moreover, we show that the attractive and repulsive polarons respond differently to an increasing dissipation range in our model. Finally, we exhibit the polaron energy, residue, effective mass, and two-body decay for mass-balanced and imbalanced systems. Our results might be useful for cold-atom experiments on open quantum systems.展开更多
基金supported by HK RGC(ECS-209813)NSF of China(NSFC-21303151)+2 种基金HKBU FRG(FRG2/12-13/037)startup funds(38-40-088 and 40-49-495)to K.-Y.WongThe computing resources for our work summarized in this Review were supported in part by Minnesota Supercomputing Institute,and High Performance Cluster Computing Centre and Office of Information Technology at HKBU(sciblade&jiraiya).
文摘Feynman’s path integral reformulates the quantum Schrödinger differential equation to be an integral equation.It has been being widely used to compute internuclear quantum-statistical effects on many-body molecular systems.In this Review,the molecular Schrödinger equation will first be introduced,together with the BornOppenheimer approximation that decouples electronic and internuclear motions.Some effective semiclassical potentials,e.g.,centroid potential,which are all formulated in terms of Feynman’s path integral,will be discussed and compared.These semiclassical potentials can be used to directly calculate the quantum canonical partition function without individual Schrödinger’s energy eigenvalues.As a result,path integrations are conventionally performed with Monte Carlo and molecular dynamics sampling techniques.To complement these techniques,we will examine how Kleinert’s variational perturbation(KP)theory can provide a complete theoretical foundation for developing non-sampling/non-stochastic methods to systematically calculate centroid potential.To enable the powerful KP theory to be practical for many-body molecular systems,we have proposed a new path-integral method:automated integrationfree path-integral(AIF-PI)method.Due to the integration-free and computationally inexpensive characteristics of our AIF-PI method,we have used it to perform ab initio path-integral calculations of kinetic isotope effects on proton-transfer and RNA-related phosphoryl-transfer chemical reactions.The computational procedure of using our AIF-PI method,along with the features of our new centroid path-integral theory at the minimum of the absolute-zero energy(AMAZE),are also highlighted in this review.
基金Project supported by the State Key Development Program for Basic Research of China(Grant No.2017YFA0304300)the National Natural Science Foundation of China(Grant Nos.11934018,11747601,and 11975294)+4 种基金Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB28000000)Scientific Instrument Developing Project of Chinese Academy of Sciences(Grant No.YJKYYQ20200041)Beijing Natural Science Foundation(Grant No.Z200009)the Key-Area Research and Development Program of Guangdong Province,China(Grant No.2020B0303030001)Chinese Academy of Sciences(Grant No.QYZDB-SSW-SYS032)。
文摘Quantum computers promise to solve finite-temperature properties of quantum many-body systems,which is generally challenging for classical computers due to high computational complexities.Here,we report experimental preparations of Gibbs states and excited states of Heisenberg X X and X X Z models by using a 5-qubit programmable superconducting processor.In the experiments,we apply a hybrid quantum–classical algorithm to generate finite temperature states with classical probability models and variational quantum circuits.We reveal that the Hamiltonians can be fully diagonalized with optimized quantum circuits,which enable us to prepare excited states at arbitrary energy density.We demonstrate that the approach has a self-verifying feature and can estimate fundamental thermal observables with a small statistical error.Based on numerical results,we further show that the time complexity of our approach scales polynomially in the number of qubits,revealing its potential in solving large-scale problems.
基金Supported by the National Natural Science Foundation of China (Grant No.11674282)the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No.XDB28000000)。
文摘Recent experiments have demonstrated the realization of the three-dimensional quantum Hall effect in highly anisotropic crystalline materials, such as ZrTe|_5 and BaMnSb_2. Such a system supports chiral surface states in the presence of a strong magnetic field, which exhibit a one-dimensional metal-insulator crossover due to suppression of surface diffusion by disorder potential. We study the nontrivial surface states in a lattice model and find a wide crossover of the level-spacing distribution through a semi-Poisson distribution. We also discover a nonmonotonic evolution of the level statistics due to the disorder-induced mixture of surface and bulk states.
基金Project supported by the National Natural Science Foundation of China(Grant No.11464033)
文摘With hydrogen-like impurity(HLI) located in the center of Cs I quantum pseudodot(QPD) and by using the variational method of Pekar type(VMPT), we investigate the first-excited state energy(FESE), excitation energy and transition frequency of the strongly-coupled bound polaron in the present paper. Temperature effects on bound polaron properties are calculated by employing the quantum statistical theory(QST). According to the present work's numerical results, the FESE, excitation energy and transition frequency decay(amplify) with raising temperature in the regime of lower(higher)temperature. They are decreasing functions of Coulomb impurity potential strength.
文摘In weak measurement thought experiment, an ensemble consists of M quantum particles and N states. We observe that separability of the particles is lost, and hence we have fuzzy occupation numbers for the particles in the ensemble. Without sharply measuring each particle state, quantum interferences add extra possible configurations of the ensemble, this explains the Quantum Pigeonhole Principle. This principle adds more entropy to the system;hence the particles seem to have a new kind of correlations emergent from particles not having a single, well-defined state. We formulated the Quantum Pigeonhole Principle in the language of abstract Hilbert spaces, then generalized it to systems consisting of mixed states. This insight into the fundamentals of quantum statistical mechanics could help us understand the interpretation of quantum mechanics more deeply, and possibly have implication on quantum computing and information theory.
基金Project supported by the National Key R&D Program of China(Grant No.2018YFA0306703)the National Science Foundation of China(Grant Nos.12050410253,92065115,and 12274059)+1 种基金the Ministry of Science and Technology of China(Grant No.QNJ2021167001L)the National Science Foundation of China for the International Young Scientists Fund(Grant No.12250410242)。
文摘In contrast to interferometry-based quantum sensing,where interparticle interaction is detrimental,quantum many-body probes exploit such interactions to achieve quantum-enhanced sensitivity.In most of the studied quantum many-body probes,the interaction is considered to be short-ranged.Here,we investigate the impact of long-range interaction at various filling factors on the performance of Stark quantum probes for measuring a small gradient field.These probes harness the ground state Stark localization phase transition which happens at an infinitesimal gradient field as the system size increases.Our results show that while super-Heisenberg precision is always achievable in all ranges of interaction,the long-range interacting Stark probe reveals two distinct behaviors.First,by algebraically increasing the range of interaction,the localization power is enhanced and thus the sensitivity of the probe decreases.Second,as the interaction range becomes close to a fully connected graph its effective localization power disappears and thus the sensitivity of the probe starts to enhance again.The super-Heisenberg precision is achievable throughout the extended phase until the transition point and remains valid even when the state preparation time is incorporated in the resource analysis.As the probe enters the localized phase,the sensitivity decreases and its performance becomes size-independent,following a universal behavior.In addition,our analysis shows that lower filling factors lead to better precision for measuring weak gradient fields.
文摘This document will from first principles delineate the degree of flatness, or deviations from, in early universe models. We will, afterwards, make comparison with recent results we have looked at concerning metric tensor fluctuations and comment upon the role of what early universe gravitational energy may play a role in the presumed deviation from flat space results. Note that N~S<sub>initial(graviton)</sub>~10<sup>37 </sup>will be tied into the presumed results for initial state density, in ways we will comment upon, leading to observations which are supporting the physics given by Equation (26) of this document as with regards to Gravitational waves, from relic conditions. The deviations from flat space may help confirm the conclusions given by Buchert, Carfora, Kolb, and Wiltshire allegedly refuting the claim by Green and Wald that “the standard FLRW model approximates our Universe extremely well on all scales, except close to strong field astrophysical objects”, as well as give additional analysis appropriate for adding detail to expanding experimental procedures for investigating non FLRW models such as the Polynomial Inflation models as given by Kobayashi, and Seto, as well as other nonstandard cosmologies, as brought up by Corda, and other researchers. As well as improve upon post Bicep 2 measurements which will avoid GW signatures from interstellar dust, as opposed to relic GW. We hope that our approach may help in the differentiation between different cosmology models. Most importantly, our procedure may help, with refinement of admissible frequency range, avoid the problem of BICEP 2, which had its presumed GW signals from presumed relic conditions identical to dust induced frequencies, as so identified by the Planck collaboration in reference [25] which we comment upon in the conclusion.
基金Project supported by the National Natural Science Foundation of China(Grant No.11175023)partially by the Open Fund of National Laboratory of Science and Technology on Computational Physics at Institute of Applied Physics and Computational Mathematics in Beijing
文摘Based on the quantum Vlasov equation, the effect of frequency chirp on electron-positron pair production is investigated. The cycle parameter, which characterizes the laser field cycle degree within the pulse, is also considered. In both supercycle and subcycle laser pulses the frequency chirp can greatly enhance the momentum distribution function of created pairs and the pair number density. The pair number density created by a supercycle laser pulse is larger than that by a subcycle pulse under the same laser frequency and chirping. There exists an optimal cycle parameter corresponding to the maximum value of the created pair number density for different chirp rates. It is found that the pair number density is sensitive/insensitive to chirping rate when the cycle parameter lies below/above the optimal one.
基金supported by the Natural Science Foundation of Shanxi Province,China(Grant No 2006011012)the Doctoral Scientific Research Starting Foundation of Shanxi Datong University,China
文摘By using the entanglement entropy method, this paper calculates the statistical entropy of the Bose and Fermi fields in thin films, and derives the Bekenstein-Hawking entropy and its correction term on the background of a rotating and charged black string. Here, the quantum field is entangled with quantum states in the black string and thin film to the event horizon from outside the rotating and charged black string. Taking into account the effect of the generalized uncertainty principle on quantum state density, it removes the difficulty of the divergence of state density near the event horizon in the brick-wall model. These calculations and discussions imply that high density quantum states near the event horizon of a black string are strongly correlated with the quantum states in a black string and that black string entropy is a quantum effect. The ultraviolet cut-off in the brick-wall model is not reasonable. The generalized uncertainty principle should be considered in the high energy quantum field near the event horizon. From the viewpoint of quantum statistical mechanics, the correction value of Bekenstein-Hawking entropy is obtained. This allows the fundamental recognition of the correction value of black string entropy at nonspherical coordinates.
文摘We look at what may occur if Boltzmann equations, as presented by Murayama in 2007, Les Houches, are applied to graviton density in a pre-Planckian universe setting. Two restrictions are in order. First of all, we are assuming a graviton mass on the order of 10?62 grams, as if the pre-Planckian regime does not change the nature of Graviton mass, in its low end. Secondly, we are also assuming that a comparatively low temperature regime (far below the Planckian temperature) exists. Finally we are leaving unsaid what may happen if Gravitational waves enter the Planck regime of ultra-high temperature. With those three considerations, we proceed to examine a Graviton density value resulting from perturbation from low to higher temperatures. In the end an ultra- hot Pre big bang cosmology will yield essentially no early universe information transfer crossovers to our present cosmological system. This is not affected by the choice if we have a single repeating universe, or a multiverse. A cold pre inflationary state yields a very different situation. Initial frequencies of Gravitons, though, as outlined may be different in the multiverse case, as opposed to the single repeating universe case. We close with comments as to Bicep 2, and how this document has material as to how to avoid the BICEP 2 disaster. And about choosing between either the possibility of massless Scalar-Tensor Gravity as the correct theory of gravitation or conventional GR.
文摘We initially look at a nonsingular universe representation of entropy, based in part on what is brought up by Muller and Lousto. This is a gateway to bring up information and computational steps (as defined by Seth Lloyd) as to what will be available initially due to a modified Zero Point Energy formalism. The Zero Point Energy formalism is modified as due to Vissers’s setting of an angular plane number in early universe cosmology as k(maximum) ~ 1/(Planck length), with a specific initial density giving rise to initial information content which may permit fixing the initial Planck’s constant, h, which is pivotal to the setting of physical law. This will be in the spirit of Stoica’s removal of initial conditions of non-pathological initial starting points in Cosmology. What we want are necessary and sufficient conditions so h(today) = h(initial). We also in addition make a brief survey into 5th force arguments in gravity which also has a strict entropy interpretation. i.e., how to link gravity, quantum mechanics, and E and M through entropy production.
文摘Using the divergence term appearing in the Lagrangian of the teleparallel equivalent of general relativity (TEGR), we calculate the thermodynamic quantities of four tetrads' spacetime reproducing Lense-Thirring (LT) metric. We also investigate the first law of thermodynamics and the quantum statistical relation.
文摘As a very simple model,the Ising model plays an important role in statistical physics.In the paper,with the help of quantum Liouvillian statistical theory,we study the one-dimensional nonHermitian Ising model at finite temperature and give its analytical solutions.We find that the nonHermitian Ising model shows quite different properties from those of its Hermitian counterpart.For example,the‘pseudo-phase transition’is explored between the‘topological’phase and the‘nontopological’phase,at which the Liouvillian energy gap is closed rather than the usual energy gap.In particular,we point out that the one-dimensional non-Hermitian Ising model at finite temperature can be equivalent to an effective anisotropic XY model in the transverse field.This work will help people understand quantum statistical properties of non-Hermitian systems at finite temperatures.
文摘Recently an f -deformed Fock space which is spanned by | n λ was introduced. These bases are the eigenstates of a deformed non-Hermitian Hamiltonian. In this contribution, we will use rather new nonorthogonal basis vectors for the construction of coherent and squeezed states, which in special case lead to the earlier known states. For this purpose, we first generalize the previously introduced Fock space spanned by | n λ bases, to a new one, spanned by extended two-parameters bases | n λ 1 ,λ 2 . These bases are now the eigenstates of a non-Hermitian Hamiltonian H λ 1 ,λ 2 = a λ 1 ,λ 2 a + 1 2 , where a λ 1 ,λ 2 = a + λ 1 a + λ 2 and a are, respectively, the deformed creation and ordinary bosonic annihilation operators. The bases | n λ 1 ,λ 2 are nonorthogonal (squeezed states), but normalizable. Then, we deduce the new representations of coherent and squeezed states in our two-parameter Fock space. Finally, we discuss the quantum statistical properties, as well as the non-classical properties of the obtained states numerically.
基金supported by the National Natural Science Foundation of China (Grant Nos. 11704029, and 12174024)supported by the National Natural Science Foundation of China (Grant No. 11504038)。
文摘The study of the polaron of an open quantum system plays an important role in verifying the effectiveness of an approximate many-body theory and predicting novel quantum phenomena in open quantum systems. In a pioneering work, Piazza et al.(2021) proposed a Fermi-polaron scheme with a lossy impurity, which exhibits a novel long-lived attractive polaron branch in the quantum Zeno limit. However, we have encountered a counterpart problem in which an impurity interacting with an open quantum bath scatters exciting polarons, which is what we focus on. In this work, we determine through analytical research the molecular state under the two limits of vanishingly small and infinitely large dissipation intensities as well as the reason why the dissipation range leads to a decrease in the gap between the molecular state and the molecule-hole continuum in the former case.The spectrum functions of molecular and polaron states with different dissipation ranges and loss rates are investigated. We find the spectral signals of molecular and polaron states will first diffuse and then revive as the dissipation increases. Moreover, we show that the attractive and repulsive polarons respond differently to an increasing dissipation range in our model. Finally, we exhibit the polaron energy, residue, effective mass, and two-body decay for mass-balanced and imbalanced systems. Our results might be useful for cold-atom experiments on open quantum systems.