We conduct a theoretical study on the properties of a bound polaron in a quantum well under an electric field using linear combination operator and unitary transformation methods, which are valid in the whole range of...We conduct a theoretical study on the properties of a bound polaron in a quantum well under an electric field using linear combination operator and unitary transformation methods, which are valid in the whole range of electron-LO phonon coupling. The changing relations between the ground-state energy of the bound polaron in the quantum well and the Coulomb bound potential, the electric field strength, and the well width are derived. The numerical results show that the ground-state energy increases with the increase of the electric field strength and the Coulomb bound potential and decreases as the well width increases.展开更多
The influence of the electric field on the properties of the bound magnetopolaron in an infinite-depth GaAs semiconductor quantum well is investigated using the linear-combination operator and the unitary transformati...The influence of the electric field on the properties of the bound magnetopolaron in an infinite-depth GaAs semiconductor quantum well is investigated using the linear-combination operator and the unitary transformation method. The relationships between the polaron＇s ground state energy and the Coulomb bound potential, electric field, magnetic field, and well-width are derived and discussed. Our numerical results show that the absolute value of the polaron＇s ground state energy increases as the electric field and the Coulomb bound potential increase, and decreases as the well-width and the magnetic field strength increase. When the well-width is small,the quantum size effect is significant.展开更多
The binding energy and the photon energy dependence of the photoionization cross-section are calculated for a hydrogenic impurity in GaAs/Ga 1-xAl xAs quantum well wires.The correlation between confined and non-co...The binding energy and the photon energy dependence of the photoionization cross-section are calculated for a hydrogenic impurity in GaAs/Ga 1-xAl xAs quantum well wires.The correlation between confined and non-confined direction of the wire in the variational wave function is taken into account.The results show that the photoionization cross-sections are affected by the width of the wire and that their magnitudes are larger than those in infinite potential quantum well wires.In comparison with previous's results,the variational wave function improves the binding energy and decreases the value of photoionization cross-sections of the hydrogenic impurities,which makes the results more reasonable.展开更多
The properties of a bound polaron in a parabolic quantum dot with weak electron-LO-phonon coupling under a Coulomb field are studied. The ground state energy of the bound polaron is derived by using a linear combinati...The properties of a bound polaron in a parabolic quantum dot with weak electron-LO-phonon coupling under a Coulomb field are studied. The ground state energy of the bound polaron is derived by using a linear combination operator and the perturbation method. The influence of the interaction between phonons with different wave vectors in the recoil process on the ground state energy of the bound polaron is discussed. Numerical calculations are performed,and the results show that the ground state energy increases significantly as the effective confinement length of the quantum dot decreases,considering of the interaction between phonons. When l0〉1.0, the influence of the interaction between phonons on the ground state energy cannot be ignored.展开更多
The binding energy of a bound polaron in a finite parabolic quantum well is studied theoretically by a fractional- dimensional variational method. The numerical results for the binding energies of the bound polaron an...The binding energy of a bound polaron in a finite parabolic quantum well is studied theoretically by a fractional- dimensional variational method. The numerical results for the binding energies of the bound polaron and longitudinal-optical phonon contributions in GaAs/Al0.3 Ga0.7 AS parabolic quantum well structures are obtained as functions of the well width. It is shown that the binding energies of the bound polaron are obviously reduced by the electron-phonon interaction and the phonon contribution is observable and cannot be neglected.展开更多
A model is proposed to study the quantum rings with two deeply bound electrons under a variable magnetic field. The emphasis is placed to clarify the effect of the size （diameter） and the width of the ring on the fr...A model is proposed to study the quantum rings with two deeply bound electrons under a variable magnetic field. The emphasis is placed to clarify the effect of the size （diameter） and the width of the ring on the fractional Aharonov-Bohm oscillation. It was found that the reduction of size will lead to a very strong oscillation in the ground state energy and in the persistent current. The electronic correlation has also been demonstrated by showing the nodal structures of wave functions.展开更多
We re-examine physical causal propagators for scalar and pseudoscalar bound states at finite temperature in a chiral NJL model, defined by four-point amputated functions subtracted through the gap equation, and prove...We re-examine physical causal propagators for scalar and pseudoscalar bound states at finite temperature in a chiral NJL model, defined by four-point amputated functions subtracted through the gap equation, and prove that they are completely equivalent in the imaginary-time and real-time formalisms by separating carefully the imaginary part of the zero-temperature loop integral. It is shown that the same thermal transformation matrix of the matrix propagators for these bound states in the real-time formalism is precisely the one of the matrix propagator for an elementary scalar particle and this fact shows the similarity of thermodynamic property between a composite and elementary scalar particle. The retarded and advanced propagators for these bound states are also given explicitly from the imaginary-time formalism.展开更多
By exact resolution of coupled ideal chains connecting an extra side site,we show that the so-called'anti-resonant effect' is suppressed when the electron energy is inside the overlap region of extended bands ...By exact resolution of coupled ideal chains connecting an extra side site,we show that the so-called'anti-resonant effect' is suppressed when the electron energy is inside the overlap region of extended bands of the idealtight-binding chains.When the electronic energy is outside the band overlap region,the existence of 'anti-resonanteffect' is tuned by details of local connectivity around the extra side site and can be suppressed by introduction ofmagnetic flux.展开更多
We report full-dimensional and fully coupled quantum bound-state calculations of the J=1 intra-and intermolecular rovibrational states of two isotopologues of the hydrogen chloride-water dimer,HClH_(2)O(HH)and DCl-H_(...We report full-dimensional and fully coupled quantum bound-state calculations of the J=1 intra-and intermolecular rovibrational states of two isotopologues of the hydrogen chloride-water dimer,HClH_(2)O(HH)and DCl-H_(2)O(DH).The present study complements our recent theoretical investigations of the J=0 nine-dimensional(9D)vibrational level structure of these and two other H/D isotopologues of this noncovalently bound molecular complex,and employs the same accurate 9D permutation invariant polynomial-neural network potential energy surface.The calculations yield all intramolecular vibrational fundamentals of the HH and DH dimers and the low-energy intermolecular rovibrational states in these intramolecular vibrational manifolds.The results are compared with those of the 9D J=0 calculations of the same dimers.The energy differences between the K=1 and K=0 eigenstates exhibit pronounced variations with the intermolecular rovibrational states,for which a qualitative explanation is provided.展开更多
Feynman variational path integral theory was used to obtain the ground state energy of a polaron in a quantum well in the presence of a Coulomb potential for arbitrary values of the electron phonon coupling constan...Feynman variational path integral theory was used to obtain the ground state energy of a polaron in a quantum well in the presence of a Coulomb potential for arbitrary values of the electron phonon coupling constant α . Numerical and analytical results showed that the energy shift was more sensitive to α than to the Coulomb binding parameter ( β ) and increased with the decrease of effective quantum well width l Z . It was interesting that due to the electronic confinement in the quasi 2D (quantum well) structures, the lower bound of the strong coupling regime was shifted to smaller values of α . Comparison of the polaron in the quantum well with that in the quantum wire or dot showed that the polaronic effect strengthened with decrease of the confinement dimension.展开更多
In this article, we take the vector charmonium-like state Y（4660） as a φ＇ fo（980） bound state （irrespective of the hadro-charmonium and the molecular state） tentatively, and study its mass using the QCD sum ru...In this article, we take the vector charmonium-like state Y（4660） as a φ＇ fo（980） bound state （irrespective of the hadro-charmonium and the molecular state） tentatively, and study its mass using the QCD sum rules. The numerical value My = 4.71 ±0.26 GeV is consistent with the experimental data. Considering the SU（3） symmetry of the light flavor quarks and the heavy quark symmetry, we also study the bound states φ＇a（400-1200）, γ′″ fo（980）, and γ′″σ（400-1200） with the QCD sum rules, and make reasonable predictions for their masses.展开更多
We study the electron transport through a special quantum-dot(QD)structure composed of three QDs and two Majorana bound states(MBSs)using the nonequilibrium Green’s function technique.This QD-MBS ring structure inclu...We study the electron transport through a special quantum-dot(QD)structure composed of three QDs and two Majorana bound states(MBSs)using the nonequilibrium Green’s function technique.This QD-MBS ring structure includes two channels with the two coupled MBSs being Channel 1 and one QD being Channel 2,and three types of transport processes such as the electron transmission(ET),the Andreev reflection(AR),and the crossed Andreev reflection(CAR).By comparing the ET,AR,and CAR processes through Channels 1 and 2,we make a systematic study on the transport properties of the QD-MBS ring.It is shown that there appear two kinds of characteristic transport patterns for Channels 1 and 2,as well as the interplay between the two patterns.Of particular interest is that there exists an AR-assisted ET process in Channel 2,which is different from that in Channel 1.Thus a clear"X"pattern due to the ET and AR processes appears in the ET,AR,and CAR transmission coefficients.Moreover,we study how Channel 2 affects the three transport processes when Channel 1 is tuned in the ET and CAR regimes.It is shown that the transport properties of the ET,AR and CAR processes can be adjusted by tuning the energy level of the QD embedded in Channel 2.We believe this research should be a helpful reference for understanding the transport properties in the QD-MBS coupled systems.展开更多
基金Supported by National Science Fundation of China(60878002)the Science and Technology Committee of Guangdong Province(2010A080802002,2010B080704002,2010B010800031,2010B090400130 and 8251009101000002)the Science and Technology Bureau of Guangzhou(2009J1-C421-1)
文摘We conduct a theoretical study on the properties of a bound polaron in a quantum well under an electric field using linear combination operator and unitary transformation methods, which are valid in the whole range of electron-LO phonon coupling. The changing relations between the ground-state energy of the bound polaron in the quantum well and the Coulomb bound potential, the electric field strength, and the well width are derived. The numerical results show that the ground-state energy increases with the increase of the electric field strength and the Coulomb bound potential and decreases as the well width increases.
文摘The influence of the electric field on the properties of the bound magnetopolaron in an infinite-depth GaAs semiconductor quantum well is investigated using the linear-combination operator and the unitary transformation method. The relationships between the polaron＇s ground state energy and the Coulomb bound potential, electric field, magnetic field, and well-width are derived and discussed. Our numerical results show that the absolute value of the polaron＇s ground state energy increases as the electric field and the Coulomb bound potential increase, and decreases as the well-width and the magnetic field strength increase. When the well-width is small,the quantum size effect is significant.
文摘The binding energy and the photon energy dependence of the photoionization cross-section are calculated for a hydrogenic impurity in GaAs/Ga 1-xAl xAs quantum well wires.The correlation between confined and non-confined direction of the wire in the variational wave function is taken into account.The results show that the photoionization cross-sections are affected by the width of the wire and that their magnitudes are larger than those in infinite potential quantum well wires.In comparison with previous's results,the variational wave function improves the binding energy and decreases the value of photoionization cross-sections of the hydrogenic impurities,which makes the results more reasonable.
文摘The properties of a bound polaron in a parabolic quantum dot with weak electron-LO-phonon coupling under a Coulomb field are studied. The ground state energy of the bound polaron is derived by using a linear combination operator and the perturbation method. The influence of the interaction between phonons with different wave vectors in the recoil process on the ground state energy of the bound polaron is discussed. Numerical calculations are performed,and the results show that the ground state energy increases significantly as the effective confinement length of the quantum dot decreases,considering of the interaction between phonons. When l0〉1.0, the influence of the interaction between phonons on the ground state energy cannot be ignored.
文摘The binding energy of a bound polaron in a finite parabolic quantum well is studied theoretically by a fractional- dimensional variational method. The numerical results for the binding energies of the bound polaron and longitudinal-optical phonon contributions in GaAs/Al0.3 Ga0.7 AS parabolic quantum well structures are obtained as functions of the well width. It is shown that the binding energies of the bound polaron are obviously reduced by the electron-phonon interaction and the phonon contribution is observable and cannot be neglected.
基金The project supported by the National Natural Science Foundation of China under Grant Nos. 10574163 and 90306016.Acknowledgments The author wishes to thank Prof. C.G. Bao and Mr. G.M. Huang for their helpful discussions.
文摘A model is proposed to study the quantum rings with two deeply bound electrons under a variable magnetic field. The emphasis is placed to clarify the effect of the size （diameter） and the width of the ring on the fractional Aharonov-Bohm oscillation. It was found that the reduction of size will lead to a very strong oscillation in the ground state energy and in the persistent current. The electronic correlation has also been demonstrated by showing the nodal structures of wave functions.
文摘We re-examine physical causal propagators for scalar and pseudoscalar bound states at finite temperature in a chiral NJL model, defined by four-point amputated functions subtracted through the gap equation, and prove that they are completely equivalent in the imaginary-time and real-time formalisms by separating carefully the imaginary part of the zero-temperature loop integral. It is shown that the same thermal transformation matrix of the matrix propagators for these bound states in the real-time formalism is precisely the one of the matrix propagator for an elementary scalar particle and this fact shows the similarity of thermodynamic property between a composite and elementary scalar particle. The retarded and advanced propagators for these bound states are also given explicitly from the imaginary-time formalism.
基金Supported by the National Natural Science Foundation of China under Grant No.10604006Super Computer Center of Beijing Normal University
文摘By exact resolution of coupled ideal chains connecting an extra side site,we show that the so-called'anti-resonant effect' is suppressed when the electron energy is inside the overlap region of extended bands of the idealtight-binding chains.When the electronic energy is outside the band overlap region,the existence of 'anti-resonanteffect' is tuned by details of local connectivity around the extra side site and can be suppressed by introduction ofmagnetic flux.
基金the National Science Foundation for its partial support of this research through the Grants CHE-2054616 and CHE-2054604,respectively。
文摘We report full-dimensional and fully coupled quantum bound-state calculations of the J=1 intra-and intermolecular rovibrational states of two isotopologues of the hydrogen chloride-water dimer,HClH_(2)O(HH)and DCl-H_(2)O(DH).The present study complements our recent theoretical investigations of the J=0 nine-dimensional(9D)vibrational level structure of these and two other H/D isotopologues of this noncovalently bound molecular complex,and employs the same accurate 9D permutation invariant polynomial-neural network potential energy surface.The calculations yield all intramolecular vibrational fundamentals of the HH and DH dimers and the low-energy intermolecular rovibrational states in these intramolecular vibrational manifolds.The results are compared with those of the 9D J=0 calculations of the same dimers.The energy differences between the K=1 and K=0 eigenstates exhibit pronounced variations with the intermolecular rovibrational states,for which a qualitative explanation is provided.
文摘Feynman variational path integral theory was used to obtain the ground state energy of a polaron in a quantum well in the presence of a Coulomb potential for arbitrary values of the electron phonon coupling constant α . Numerical and analytical results showed that the energy shift was more sensitive to α than to the Coulomb binding parameter ( β ) and increased with the decrease of effective quantum well width l Z . It was interesting that due to the electronic confinement in the quasi 2D (quantum well) structures, the lower bound of the strong coupling regime was shifted to smaller values of α . Comparison of the polaron in the quantum well with that in the quantum wire or dot showed that the polaronic effect strengthened with decrease of the confinement dimension.
基金Supported by National Natural Science Foundation under Grant No.10775051 Program for New Century Excellent Talents in University under Grant No.NCET-07-0282 Project Supported by Chinese Universities Scientific Fund
文摘In this article, we take the vector charmonium-like state Y（4660） as a φ＇ fo（980） bound state （irrespective of the hadro-charmonium and the molecular state） tentatively, and study its mass using the QCD sum rules. The numerical value My = 4.71 ±0.26 GeV is consistent with the experimental data. Considering the SU（3） symmetry of the light flavor quarks and the heavy quark symmetry, we also study the bound states φ＇a（400-1200）, γ′″ fo（980）, and γ′″σ（400-1200） with the QCD sum rules, and make reasonable predictions for their masses.
基金Supported by National Natural Science Foundation of China under Grant No.11274040the Program for New Century Excellent Talents in University under Grant No.NCET-08-0044
文摘We study the electron transport through a special quantum-dot(QD)structure composed of three QDs and two Majorana bound states(MBSs)using the nonequilibrium Green’s function technique.This QD-MBS ring structure includes two channels with the two coupled MBSs being Channel 1 and one QD being Channel 2,and three types of transport processes such as the electron transmission(ET),the Andreev reflection(AR),and the crossed Andreev reflection(CAR).By comparing the ET,AR,and CAR processes through Channels 1 and 2,we make a systematic study on the transport properties of the QD-MBS ring.It is shown that there appear two kinds of characteristic transport patterns for Channels 1 and 2,as well as the interplay between the two patterns.Of particular interest is that there exists an AR-assisted ET process in Channel 2,which is different from that in Channel 1.Thus a clear"X"pattern due to the ET and AR processes appears in the ET,AR,and CAR transmission coefficients.Moreover,we study how Channel 2 affects the three transport processes when Channel 1 is tuned in the ET and CAR regimes.It is shown that the transport properties of the ET,AR and CAR processes can be adjusted by tuning the energy level of the QD embedded in Channel 2.We believe this research should be a helpful reference for understanding the transport properties in the QD-MBS coupled systems.
