The asymmetric parabolic double quantum wells (DQWs) with resonant levels (the ground state energy in one well co-incides with the first excited state energy in another well) is analyzed. The splitting of these levels...The asymmetric parabolic double quantum wells (DQWs) with resonant levels (the ground state energy in one well co-incides with the first excited state energy in another well) is analyzed. The splitting of these levels and the tunneling times are calculated. If the typical life time of the excited state is much smaller than the tunneling time between wells, the charged particle can radiate as a result of the quantum transition from the excited state to the ground state. In the opposite case, the asymmetric DQWs can be treated as a metastable excited nanosystem regardless of that the dipole transition from the excited state to ground state is permitted. The lifetime of this metastable state can be considerably reduced by putting it into a resonant cavity. The possibility of coherent radiation of an ensemble of asymmetric DQWS is discussed.展开更多
The paper analyzes the concept of Ether and substantiates the necessity of its existence as a physical reality, which arises within the framework of the concept developed by the authors of the work. The authors come t...The paper analyzes the concept of Ether and substantiates the necessity of its existence as a physical reality, which arises within the framework of the concept developed by the authors of the work. The authors come to the conclusion that the existence of Ether in two different forms, plays an exceptional role in the formation of Dark Matter and Dark Energy and leads to the emergence of exotic cosmological structures and their hierarchy in energy, temporal, and spatial scale. The mechanism of the formation of physical structures before the Big Bang and their further evolution, up to the formation of worlds of galaxies and stars, is considered. The necessity of the emergence of exotic structures, such as 3 spheres of the Primary Relict, is shown, its structure and dynamic properties leading to the formation of Order from Chaos are considered. The role of the 1st and 2nd type Ether in the formation of the mechanism of transformation of cosmic energies and quantum phase transitions, in the process of the birth and evolution of the Universe is discussed. The conclusion is made about the existence of universal properties of matter, at the level of Macro and Microcosms, and a multidimensional cosmological model with an isothermal temperature distribution is constructed, leading to a discrete distribution of matter separated by transitions, by analogy with Black-and-White Holes. It is shown that the postulate of the constancy of the speed of light in any inertial system is a consequence of the principle of covariance.展开更多
We investigate the role of quantum correlation around the quantum phase transitions by using quantum renormalization group theory. Numerical analysis indicates that quantum correlation as well as quantum nonlocality c...We investigate the role of quantum correlation around the quantum phase transitions by using quantum renormalization group theory. Numerical analysis indicates that quantum correlation as well as quantum nonlocality can efficiently detect the quantum critical point in the two-dimensional XY systems. The nonanalytic behavior of the first derivative of quantum correlation is observed at the critical point as the size of the model increases. Furthermore, we discuss the quantum correlation distribution in this system based on the square of concurrence（SC） and square of quantum discord（SQD）. The monogamous properties of SC and SQD are obtained. Particularly, we prove that the quantum critical point can also be achieved by monogamy score.展开更多
Fidelity measures the similarity between two states and is widely adapted by the condensed matter community as a probe of quantum phase transitions in many-body systems. Despite its success in witnessing quantum criti...Fidelity measures the similarity between two states and is widely adapted by the condensed matter community as a probe of quantum phase transitions in many-body systems. Despite its success in witnessing quantum critical points, information about the fine structure of a quantum phase one can get from this approach is still limited. Here, we proposed a scheme called fidelity spectrum, By studying the fidelity spectrum, one can obtain information about the characteristics of a phase. In particular, we investigated the spectra in the one-dimensional transverse-field Ising model and the two- dimensional Kitaev model on a honeycomb lattice. It was found that the sPectra have qualitative differences in the critical and non-critical regions of the two models. From the distributions of them, the dominating k modes in a particular phase could also be captured.展开更多
The study of non-Hermitian systems with parity-time(PT)symmetry is a rapidly developing frontier in recent years?Experimentally,PT-symmetric systems have been realized in classical optics by balancing gain and loss,wh...The study of non-Hermitian systems with parity-time(PT)symmetry is a rapidly developing frontier in recent years?Experimentally,PT-symmetric systems have been realized in classical optics by balancing gain and loss,which holds great promise for novel optical devices and networks?Here we report experimental realization of passive PT-symmetric quantum dynamics for single photons by temporally alternating photon losses in the quantum walk(QW)interferometers.The ability to impose PT symmetry allows us to realize and investigate Floquet topological phases driven by PT-symmetric QWs.We observe topological edge states between regions with different topological invariants?Topological invariants can be defined by winding numbers,Zak phases,general geometry phases and can be calculated?Can they be detected directly?We give an answer by reporting the experimental detection of bulk topological invariants in non-unitary QWs?The topological invariant of the non-unitary quantum walk is manifested in the quantized average displacement of the walker,which is probed by monitoring the photon loss.Furthermore,we report the experimental study of dynamic quantum phase transitions(DQPTs)and photonic skyrmions using discrete-time QWs?We simulate quench dynamics between distinct Floquet topological phases using quantum-walk dynamics,and experimentally characterize DQPTs and emergent skyrmion structures.Our results pave the way for realizing quantum mechanical PT-synthetic devices and augurs exciting possibilities for exploring topological properties of non-Hermitian systems using discretetime QWs.展开更多
Heavy fermion materials are prototypical strongly correlated electron systems, where the strong electron–electron interactions lead to a wide range of novel phenomena and emergent phases of matter. Due to the low ene...Heavy fermion materials are prototypical strongly correlated electron systems, where the strong electron–electron interactions lead to a wide range of novel phenomena and emergent phases of matter. Due to the low energy scales, the relative strengths of the Ruderman–Kittel–Kasuya–Yosida(RKKY) and Kondo interactions can often be readily tuned by non-thermal control parameters such as pressure, doping, or applied magnetic fields, which can give rise to quantum criticality and unconventional superconductivity. Here we provide a brief overview of research into heavy fermion materials in high magnetic fields, focussing on three main areas. Firstly we review the use of magnetic fields as a tuning parameter,and in particular the ability to realize different varieties of quantum critical behaviors. We then discuss the properties of heavy fermion superconductors in magnetic fields, where experiments in applied fields can reveal the nature of the order parameter, and induce new novel phenomena. Finally we report recent studies of topological Kondo systems, including topological Kondo insulators and Kondo–Weyl semimetals. Here experiments in magnetic fields can be used to probe the topologically non-trivial Fermi surface, as well as related field-induced phenomena such as the chiral anomaly and topological Hall effect.展开更多
According to our scheme to construct quantum phase transitions （QPTs） in spin chain systems with matrix product ground states, we first successfully combine matrix product state （MPS） QPTs with spontaneous symmetr...According to our scheme to construct quantum phase transitions （QPTs） in spin chain systems with matrix product ground states, we first successfully combine matrix product state （MPS） QPTs with spontaneous symmetry breaking. For a concrete model, we take into account a kind of MPS QPTs accompanied by spontaneous parity breaking, though for either side of the critical point the GS is typically unique, and show that the kind of MPS QPTs occur only in the thermodynamic limit and are accompanied by the appearance of singularities, diverging correlation length, vanishing energy gap and the entanglement entropy of a half-infinite chain not only staying finite but also whose first derivative discontinuous.展开更多
In the first step, the Joule-Lenz dissipation energy specified for the electron transitions between two neighbouring quantum levels in the hydrogen atom has been compared with the electromagnetic energy of emission fr...In the first step, the Joule-Lenz dissipation energy specified for the electron transitions between two neighbouring quantum levels in the hydrogen atom has been compared with the electromagnetic energy of emission from a single level. Both the electric and magnetic vectors entering the Pointing vector of the electromagnetic field are referred to the one-electron motion performed along an orbit in the atom. In the next step, a similar comparison of emission rates is performed for the harmonic oscillator. Formally a full agreement of the Joule-Lenz and electromagnetic expressions for the energy emission rates has been attained.展开更多
We investigate the scaling of entanglement entropy for one spatial XXZ spin chain by using matrix product states to approximate ground states. The entanglement entropy scales logarithmically with a coefficient that is...We investigate the scaling of entanglement entropy for one spatial XXZ spin chain by using matrix product states to approximate ground states. The entanglement entropy scales logarithmically with a coefficient that is determined by the associated conformal field theory, the quantum phase transitions occurred between Large-D and Halde phase, Halde phase and Neel phase. The scaling relationship is given in this paper.展开更多
文摘The asymmetric parabolic double quantum wells (DQWs) with resonant levels (the ground state energy in one well co-incides with the first excited state energy in another well) is analyzed. The splitting of these levels and the tunneling times are calculated. If the typical life time of the excited state is much smaller than the tunneling time between wells, the charged particle can radiate as a result of the quantum transition from the excited state to the ground state. In the opposite case, the asymmetric DQWs can be treated as a metastable excited nanosystem regardless of that the dipole transition from the excited state to ground state is permitted. The lifetime of this metastable state can be considerably reduced by putting it into a resonant cavity. The possibility of coherent radiation of an ensemble of asymmetric DQWS is discussed.
文摘The paper analyzes the concept of Ether and substantiates the necessity of its existence as a physical reality, which arises within the framework of the concept developed by the authors of the work. The authors come to the conclusion that the existence of Ether in two different forms, plays an exceptional role in the formation of Dark Matter and Dark Energy and leads to the emergence of exotic cosmological structures and their hierarchy in energy, temporal, and spatial scale. The mechanism of the formation of physical structures before the Big Bang and their further evolution, up to the formation of worlds of galaxies and stars, is considered. The necessity of the emergence of exotic structures, such as 3 spheres of the Primary Relict, is shown, its structure and dynamic properties leading to the formation of Order from Chaos are considered. The role of the 1st and 2nd type Ether in the formation of the mechanism of transformation of cosmic energies and quantum phase transitions, in the process of the birth and evolution of the Universe is discussed. The conclusion is made about the existence of universal properties of matter, at the level of Macro and Microcosms, and a multidimensional cosmological model with an isothermal temperature distribution is constructed, leading to a discrete distribution of matter separated by transitions, by analogy with Black-and-White Holes. It is shown that the postulate of the constancy of the speed of light in any inertial system is a consequence of the principle of covariance.
基金supported by the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20171397)the National Natural Science Foundation of China(Grant Nos.11535004,11375086,1175085,and 11120101005)+1 种基金the Foundation for Encouragement of College of Sciences(Grant No.LYLZJJ1616)the Pre-research Foundation of Army Engineering University of PLA
文摘We investigate the role of quantum correlation around the quantum phase transitions by using quantum renormalization group theory. Numerical analysis indicates that quantum correlation as well as quantum nonlocality can efficiently detect the quantum critical point in the two-dimensional XY systems. The nonanalytic behavior of the first derivative of quantum correlation is observed at the critical point as the size of the model increases. Furthermore, we discuss the quantum correlation distribution in this system based on the square of concurrence（SC） and square of quantum discord（SQD）. The monogamous properties of SC and SQD are obtained. Particularly, we prove that the quantum critical point can also be achieved by monogamy score.
基金Project supported by the Earmarked Research Grant from the Research Grants Council of HKSAR,China(Grant No.CUHK 401212)
文摘Fidelity measures the similarity between two states and is widely adapted by the condensed matter community as a probe of quantum phase transitions in many-body systems. Despite its success in witnessing quantum critical points, information about the fine structure of a quantum phase one can get from this approach is still limited. Here, we proposed a scheme called fidelity spectrum, By studying the fidelity spectrum, one can obtain information about the characteristics of a phase. In particular, we investigated the spectra in the one-dimensional transverse-field Ising model and the two- dimensional Kitaev model on a honeycomb lattice. It was found that the sPectra have qualitative differences in the critical and non-critical regions of the two models. From the distributions of them, the dominating k modes in a particular phase could also be captured.
基金supported by the National Natural Science Foundation of China(Grant Nos.11674056 and U1930402)the Natural Science Foundation of Jiangsu Province(Grant No.BK20160024)the startup funding of Beijing Computational Science Research Center
文摘The study of non-Hermitian systems with parity-time(PT)symmetry is a rapidly developing frontier in recent years?Experimentally,PT-symmetric systems have been realized in classical optics by balancing gain and loss,which holds great promise for novel optical devices and networks?Here we report experimental realization of passive PT-symmetric quantum dynamics for single photons by temporally alternating photon losses in the quantum walk(QW)interferometers.The ability to impose PT symmetry allows us to realize and investigate Floquet topological phases driven by PT-symmetric QWs.We observe topological edge states between regions with different topological invariants?Topological invariants can be defined by winding numbers,Zak phases,general geometry phases and can be calculated?Can they be detected directly?We give an answer by reporting the experimental detection of bulk topological invariants in non-unitary QWs?The topological invariant of the non-unitary quantum walk is manifested in the quantized average displacement of the walker,which is probed by monitoring the photon loss.Furthermore,we report the experimental study of dynamic quantum phase transitions(DQPTs)and photonic skyrmions using discrete-time QWs?We simulate quench dynamics between distinct Floquet topological phases using quantum-walk dynamics,and experimentally characterize DQPTs and emergent skyrmion structures.Our results pave the way for realizing quantum mechanical PT-synthetic devices and augurs exciting possibilities for exploring topological properties of non-Hermitian systems using discretetime QWs.
基金Project supported by the National Natural Science Foundation of China(Grant No.U1632275)the National Key R&D Program of China(Grant Nos.2017YFA0303100 and 2016YFA0300202)the Science Challenge Project of China(Grant No.TZ2016004)
文摘Heavy fermion materials are prototypical strongly correlated electron systems, where the strong electron–electron interactions lead to a wide range of novel phenomena and emergent phases of matter. Due to the low energy scales, the relative strengths of the Ruderman–Kittel–Kasuya–Yosida(RKKY) and Kondo interactions can often be readily tuned by non-thermal control parameters such as pressure, doping, or applied magnetic fields, which can give rise to quantum criticality and unconventional superconductivity. Here we provide a brief overview of research into heavy fermion materials in high magnetic fields, focussing on three main areas. Firstly we review the use of magnetic fields as a tuning parameter,and in particular the ability to realize different varieties of quantum critical behaviors. We then discuss the properties of heavy fermion superconductors in magnetic fields, where experiments in applied fields can reveal the nature of the order parameter, and induce new novel phenomena. Finally we report recent studies of topological Kondo systems, including topological Kondo insulators and Kondo–Weyl semimetals. Here experiments in magnetic fields can be used to probe the topologically non-trivial Fermi surface, as well as related field-induced phenomena such as the chiral anomaly and topological Hall effect.
基金Supported by Scientific Research Foundation of CUIT (KYTZ201024)
文摘According to our scheme to construct quantum phase transitions （QPTs） in spin chain systems with matrix product ground states, we first successfully combine matrix product state （MPS） QPTs with spontaneous symmetry breaking. For a concrete model, we take into account a kind of MPS QPTs accompanied by spontaneous parity breaking, though for either side of the critical point the GS is typically unique, and show that the kind of MPS QPTs occur only in the thermodynamic limit and are accompanied by the appearance of singularities, diverging correlation length, vanishing energy gap and the entanglement entropy of a half-infinite chain not only staying finite but also whose first derivative discontinuous.
文摘In the first step, the Joule-Lenz dissipation energy specified for the electron transitions between two neighbouring quantum levels in the hydrogen atom has been compared with the electromagnetic energy of emission from a single level. Both the electric and magnetic vectors entering the Pointing vector of the electromagnetic field are referred to the one-electron motion performed along an orbit in the atom. In the next step, a similar comparison of emission rates is performed for the harmonic oscillator. Formally a full agreement of the Joule-Lenz and electromagnetic expressions for the energy emission rates has been attained.
文摘We investigate the scaling of entanglement entropy for one spatial XXZ spin chain by using matrix product states to approximate ground states. The entanglement entropy scales logarithmically with a coefficient that is determined by the associated conformal field theory, the quantum phase transitions occurred between Large-D and Halde phase, Halde phase and Neel phase. The scaling relationship is given in this paper.
