Floquet dynamical quantum phase transitions(DQPTs),which are nonanalytic phenomena recuring periodically in time-periodic driven quantum many-body systems,have been widely studied in recent years.In this article,the F...Floquet dynamical quantum phase transitions(DQPTs),which are nonanalytic phenomena recuring periodically in time-periodic driven quantum many-body systems,have been widely studied in recent years.In this article,the Floquet DQPTs in transverse XY spin chains under the modulation ofδ-function periodic kickings are investigated.We analytically solve the system,and by considering the eigenstate as well as the ground state as the initial state of the Floquet dynamics,we study the corresponding multiple Floquet DQPTs emerged in the micromotion with different kicking moments.The rate function of return amplitude,the Pancharatnam geometric phase and the dynamical topological order parameter are calculated,which consistently verify the emergence of Floquet DQPTs in the system.展开更多
We investigate the prominent impacts of coupling strengths on the evolution of entanglement and quantum discord for a three-qubit system coupled to an XY spin-chain environment. In the case of a pure W state, more rob...We investigate the prominent impacts of coupling strengths on the evolution of entanglement and quantum discord for a three-qubit system coupled to an XY spin-chain environment. In the case of a pure W state, more robust, even larger nonzero quantum correlations can be obtained by tailoring the coupling strengths between the qubits and the environment. For a mixed state consisting of the GHZ and W states, the dynamics of entanglement and quantum discord can characterize the critical point of quantum phase transition. Remarkably, a large nonzero quantum discord is generally retained, while the nonzero entanglement can only be obtained as the system-environment coupling satisfies certain conditions. We also find that the impact of each qubit's coupling strength on the quantum correlation dynamics strongly depends on the variation schemes of the system-environment couplings.展开更多
We use the mean-field approximation of Dyson–Maleev representation to study an XXZ Heisenberg ferrimagnetic spin chain with single-ion anisotropy. By solving the self-consistent equations with different anisotropies,...We use the mean-field approximation of Dyson–Maleev representation to study an XXZ Heisenberg ferrimagnetic spin chain with single-ion anisotropy. By solving the self-consistent equations with different anisotropies, λ and D respectively,the energy spectrums, internal energy, static susceptibility and specific heat are calculated. Especially, the quantum phase transition of the magnetization plateau induced by single-ion anisotropy D is obtained in the model of the ferrimagnetic spin chain by using Dyson–Maleev mean-field theory.展开更多
This paper studies the average fidelity of teleportation and thermal entanglement for a two-qubit Heisenberg XYZ chain in the presence of both an inhomogeneous magnetic field and a Dzyaloshinski-Moriya interaction. It...This paper studies the average fidelity of teleportation and thermal entanglement for a two-qubit Heisenberg XYZ chain in the presence of both an inhomogeneous magnetic field and a Dzyaloshinski-Moriya interaction. It shows that for a fixed Dz, the increase of bz will broaden the critical temperature at the cost of decreasing the thermal entanglement. And it can modulate the inhomogeneous magnetic field and the Dzyaloshinski-Moriya interaction for the average fidelity of teleportation to be optimal.展开更多
By using the method of density-matrix renormalization-group to solve the different spin spin correlation functions, the nearest-neighbouring entanglement (NNE) and the next-nearest-neighbouring entanglement (NNNE)...By using the method of density-matrix renormalization-group to solve the different spin spin correlation functions, the nearest-neighbouring entanglement (NNE) and the next-nearest-neighbouring entanglement (NNNE) of one-dimensional alternating Heisenberg XY spin chain are investigated in the presence of alternating the-nearestneighbouring interaction of exchange couplings, external magnetic fields and the next-nearest neighbouring interaction. For a dimerised ferromagnetic spin chain, the NNNE appears only above a critical dimerized interaction, meanwhile, the dimerized interaction a effects a quantum phase transition point and improves the NNNE to a large extent. We also study the effect of ferromagnetic or antiferromagnetic next-nearest neighbouring (NNN) interaction on the dynamics of NNE and NNNE. The ferromagnetic NNN interaction increases and shrinks the NNE below and above a critical frustrated interaction respectively, while the antiferromagnetic NNN interaction always reduces the NNE. The antiferromagnetic NNN interaction results in a large value of NNNE compared with the case where the NNN interaction is ferromagnetic.展开更多
This paper investigates the entanglement in an XX-type spin chain with Dzyaloshinskii--Moriya interaction under an external magnetic field. The von Neumann entropy of entanglement between two blocks for the ground sta...This paper investigates the entanglement in an XX-type spin chain with Dzyaloshinskii--Moriya interaction under an external magnetic field. The von Neumann entropy of entanglement between two blocks for the ground state of the system is evaluated. It analyses and discusses the scaling behaviour of the entanglement entropy.展开更多
The entanglement in one-dimensional random XY spin systems where the impurities of exchange couplings and the external magnetic fields are considered as random variables is investigated by solving the different spin-s...The entanglement in one-dimensional random XY spin systems where the impurities of exchange couplings and the external magnetic fields are considered as random variables is investigated by solving the different spin-spin correlation functions and the average magnetization per spin. The entanglement dynamics near particular locations of the system is also studied when the exchange couplings (or the external magnetic fields) satisfy three different distributions (the Gaussian distribution, double-Gaussian distribution, and bimodal distribution). We find that the entanglement can be controlled by varying the strength of external magnetic field and the distributions of impurities. Moreover, the entanglement of some nearest-neighbouring qubits can be increased for certain parameter values of the three different distributions.展开更多
An exact solution of a single impurity model is hard to derive since it breaks translation invariance symmetry. We present the exact solution of the spin-1/2 transverse Ising chain imbedded by a spin-1 impurity. Using...An exact solution of a single impurity model is hard to derive since it breaks translation invariance symmetry. We present the exact solution of the spin-1/2 transverse Ising chain imbedded by a spin-1 impurity. Using the hole decompo- sition scheme, we exactly solve the spin-1 impurity in two subspaces which are generated by a conserved hole operator. The impurity enlarges the energy deformation of the ground state above a pure transverse Ising system without impurity. The specific heat coefficient shows a small anomaly at low temperature for finite size. This indicates that the impurity can tune the ground state from a magnetic impurity space to a non-magnetic impurity space, which only exists for spin-1 impurity comparing with spin-1/2 impurity and a pure transverse Ising chain without impurity. These behaviors essentially come from adding impurity freedom, which induces a competition between hole and fermion excitation depending on the coupling strength with its neighbor and the single-ion anisotropy.展开更多
Using the method of the Jordan-Wigner transformation for solving different spin-spin correlation functions, we have investigated the generation of next-nearest-neighbouring entanglement in a one-dimensional quantum Is...Using the method of the Jordan-Wigner transformation for solving different spin-spin correlation functions, we have investigated the generation of next-nearest-neighbouring entanglement in a one-dimensional quantum Ising spin chain with the Gaussian distribution impurities of exchange couplings and external magnetic fields taken into account. The maximal value of entanglement between the next-nearest-neighbouring qubits in the transverse Ising model was analysed in detail by varying the effectively controlled parameters such as interchange coupling, magnetic field and the system impurity. For such systems, where both exchange couplings and external magnetic field disorder appear, we show that it is possible to achieve next-nearest-neighbouring entanglement better than the previously discussed pure Ising spin chain case. We also show that the Gaussian distribution impurity can induce next-nearest-neighbouring entanglement, which can be used as a means to characterize quantum phase transition.展开更多
We construct an integrable quantum spin chain that includes the nearest-neighbor,next-nearest-neighbor,chiral threespin couplings,Dzyloshinsky–Moriya interactions and unparallel boundary magnetic fields.Although the ...We construct an integrable quantum spin chain that includes the nearest-neighbor,next-nearest-neighbor,chiral threespin couplings,Dzyloshinsky–Moriya interactions and unparallel boundary magnetic fields.Although the interactions in bulk materials are isotropic,the spins nearby the boundary fields are polarized,which induce the anisotropic exchanging interactions of the first and last bonds.The U(1)symmetry of the system is broken because of the off-diagonal boundary reflections.Using the off-diagonal Bethe ansatz,we obtain an exact solution to the system.The inhomogeneous T–Q relation and Bethe ansatz equations are given explicitly.We also calculate the ground state energy.The method given in this paper provides a general way to construct new integrable models with certain interesting interactions.展开更多
Motivated by the wise idea of entanglement witness (EW), we present an inequivalent entanglement witness (IEEW) that can analogously classify certain eigenstates entangled in inequivalent ways under stochastic loc...Motivated by the wise idea of entanglement witness (EW), we present an inequivalent entanglement witness (IEEW) that can analogously classify certain eigenstates entangled in inequivalent ways under stochastic local operations and classical communication (SLOCC) in the Heisenberg spin chain. Since the IEEW is the absolute value of magnetization (M) that is a macroscopically measurable quantity, our conclusions provide a macroscopic method to detect inequivalent entanglement between microscopic spins, on the one hand, and clearly show that inequivalent entanglement can yield different macroscopic effects, on the other hand.展开更多
We consider a qubit symmetrically and transversely coupled to an XY spin chain with Dzyaloshinsky-Moriya(DM) interaction in the presence of a transverse magnetic field.An analytical expression for the geometric phas...We consider a qubit symmetrically and transversely coupled to an XY spin chain with Dzyaloshinsky-Moriya(DM) interaction in the presence of a transverse magnetic field.An analytical expression for the geometric phase of the qubit is obtained in the weak coupling limit.We find that the modification of the geometrical phase induced by the spin chain environment is greatly enhanced by DM interaction in the weak coupling limit around the quantum phase transition point of the spin chain.展开更多
Instanton configurations of (1+1)-dimensions in an antiferromagnetic biaxial-anisotropy-spin-ehain areobtained explicitly in the strong anisotropy limit,which interpolate between degenerate equilibrium orientations of...Instanton configurations of (1+1)-dimensions in an antiferromagnetic biaxial-anisotropy-spin-ehain areobtained explicitly in the strong anisotropy limit,which interpolate between degenerate equilibrium orientations of theNeel vector along easy axis and are seen to be responsible for quantum tunneling.Macroscopic quantum coherence ofthe domain walls is demonstrated in terms of the instantons.展开更多
In this paper a stochastic series expansion quantum Monte Carlo algorithm is used to study a frustratedspin chain with diagonal next-nearest-neighbor interactions.The detailed balance conditions are carefully analyzed...In this paper a stochastic series expansion quantum Monte Carlo algorithm is used to study a frustratedspin chain with diagonal next-nearest-neighbor interactions.The detailed balance conditions are carefully analyzed toimprove the efficiency of simulation process.As an application of this algothrim,the total magnetization,the staticstructure factor and spin-stiffness are calculated for a certain set of system parameters as a function of external fieldstrength.展开更多
The bidirectional transfer of information can be realized in an open Heisenberg ferromagnetic spin chain.The information is encoded in the probability distributions of the states at two end spins. The relative entropy...The bidirectional transfer of information can be realized in an open Heisenberg ferromagnetic spin chain.The information is encoded in the probability distributions of the states at two end spins. The relative entropy is used toevaluate the effective transmission of the probability. The evolution of the relative entropy shows a periodical behavior.The period is increased with increasing the length of the chain and the magnetic field while it decreases with increasingthe coupling strength.展开更多
The entanglement resonance in anisotropic spin-1/2 Heisenberg chains of different couplings is investigated when the nearest neighbor coupling is periodically modulated with external magnetic held. When the modulation...The entanglement resonance in anisotropic spin-1/2 Heisenberg chains of different couplings is investigated when the nearest neighbor coupling is periodically modulated with external magnetic held. When the modulation frequency equals twice of the magnetic held, the entanglement resonance is larger than that at other modulation frequencies and decreases as the number of spins in the chain increases. When the modulation frequency equals the magnetic held, the entanglement resonance can be reduced to a quite low value by varying the couph'ng along z axis.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.11475037)the Fundamental Research Funds for the Central Universities(Grant No.DUT19LK38)。
文摘Floquet dynamical quantum phase transitions(DQPTs),which are nonanalytic phenomena recuring periodically in time-periodic driven quantum many-body systems,have been widely studied in recent years.In this article,the Floquet DQPTs in transverse XY spin chains under the modulation ofδ-function periodic kickings are investigated.We analytically solve the system,and by considering the eigenstate as well as the ground state as the initial state of the Floquet dynamics,we study the corresponding multiple Floquet DQPTs emerged in the micromotion with different kicking moments.The rate function of return amplitude,the Pancharatnam geometric phase and the dynamical topological order parameter are calculated,which consistently verify the emergence of Floquet DQPTs in the system.
基金supported by National Basic Research Program of China(Grant No.2013CBA01702)National Natural Science Foundation of China(Grant Nos.61377016,61575055,10974039,61307072,61308017,and 61405056)
文摘We investigate the prominent impacts of coupling strengths on the evolution of entanglement and quantum discord for a three-qubit system coupled to an XY spin-chain environment. In the case of a pure W state, more robust, even larger nonzero quantum correlations can be obtained by tailoring the coupling strengths between the qubits and the environment. For a mixed state consisting of the GHZ and W states, the dynamics of entanglement and quantum discord can characterize the critical point of quantum phase transition. Remarkably, a large nonzero quantum discord is generally retained, while the nonzero entanglement can only be obtained as the system-environment coupling satisfies certain conditions. We also find that the impact of each qubit's coupling strength on the quantum correlation dynamics strongly depends on the variation schemes of the system-environment couplings.
基金Project supported by the National Natural Science Foundation of China(Grant No.10774035)the Qianjiang RenCai Program of Zhejiang Province,China(Grant No.2007R0010)
文摘We use the mean-field approximation of Dyson–Maleev representation to study an XXZ Heisenberg ferrimagnetic spin chain with single-ion anisotropy. By solving the self-consistent equations with different anisotropies, λ and D respectively,the energy spectrums, internal energy, static susceptibility and specific heat are calculated. Especially, the quantum phase transition of the magnetization plateau induced by single-ion anisotropy D is obtained in the model of the ferrimagnetic spin chain by using Dyson–Maleev mean-field theory.
基金supported by the National Natural Science Foundation of China (Grant No.60667001)
文摘This paper studies the average fidelity of teleportation and thermal entanglement for a two-qubit Heisenberg XYZ chain in the presence of both an inhomogeneous magnetic field and a Dzyaloshinski-Moriya interaction. It shows that for a fixed Dz, the increase of bz will broaden the critical temperature at the cost of decreasing the thermal entanglement. And it can modulate the inhomogeneous magnetic field and the Dzyaloshinski-Moriya interaction for the average fidelity of teleportation to be optimal.
基金Project supported by the Key Higher Education Program of Hubei Province, China (Grant No Z20052201)Natural Science Foundation of Hubei Province, China (Grant No 2006ABA055)Postgraduate Program of Hubei Normal University of China(Grant No 2007D20)
文摘By using the method of density-matrix renormalization-group to solve the different spin spin correlation functions, the nearest-neighbouring entanglement (NNE) and the next-nearest-neighbouring entanglement (NNNE) of one-dimensional alternating Heisenberg XY spin chain are investigated in the presence of alternating the-nearestneighbouring interaction of exchange couplings, external magnetic fields and the next-nearest neighbouring interaction. For a dimerised ferromagnetic spin chain, the NNNE appears only above a critical dimerized interaction, meanwhile, the dimerized interaction a effects a quantum phase transition point and improves the NNNE to a large extent. We also study the effect of ferromagnetic or antiferromagnetic next-nearest neighbouring (NNN) interaction on the dynamics of NNE and NNNE. The ferromagnetic NNN interaction increases and shrinks the NNE below and above a critical frustrated interaction respectively, while the antiferromagnetic NNN interaction always reduces the NNE. The antiferromagnetic NNN interaction results in a large value of NNNE compared with the case where the NNN interaction is ferromagnetic.
基金supported by the Teaching and Research Foundation for the Outstanding Young Faculty of Southeast University
文摘This paper investigates the entanglement in an XX-type spin chain with Dzyaloshinskii--Moriya interaction under an external magnetic field. The von Neumann entropy of entanglement between two blocks for the ground state of the system is evaluated. It analyses and discusses the scaling behaviour of the entanglement entropy.
基金Project supported by the Key Higher Education Program of Hubei Province,China(Grant No Z20052201)Natural Science Foundation of Hubei Province,China(Grant No2006ABA055)Postgraduate Program of Hubei Normal University of China(Grant No2007D20)
文摘The entanglement in one-dimensional random XY spin systems where the impurities of exchange couplings and the external magnetic fields are considered as random variables is investigated by solving the different spin-spin correlation functions and the average magnetization per spin. The entanglement dynamics near particular locations of the system is also studied when the exchange couplings (or the external magnetic fields) satisfy three different distributions (the Gaussian distribution, double-Gaussian distribution, and bimodal distribution). We find that the entanglement can be controlled by varying the strength of external magnetic field and the distributions of impurities. Moreover, the entanglement of some nearest-neighbouring qubits can be increased for certain parameter values of the three different distributions.
基金Project supported by the Xinjiang Natural Science Foundation of China(Grant No.2016D01C003)
文摘An exact solution of a single impurity model is hard to derive since it breaks translation invariance symmetry. We present the exact solution of the spin-1/2 transverse Ising chain imbedded by a spin-1 impurity. Using the hole decompo- sition scheme, we exactly solve the spin-1 impurity in two subspaces which are generated by a conserved hole operator. The impurity enlarges the energy deformation of the ground state above a pure transverse Ising system without impurity. The specific heat coefficient shows a small anomaly at low temperature for finite size. This indicates that the impurity can tune the ground state from a magnetic impurity space to a non-magnetic impurity space, which only exists for spin-1 impurity comparing with spin-1/2 impurity and a pure transverse Ising chain without impurity. These behaviors essentially come from adding impurity freedom, which induces a competition between hole and fermion excitation depending on the coupling strength with its neighbor and the single-ion anisotropy.
基金supported by the Foundation for Scientific and Technological Research Programme,Education Department of Hubei Province,China (Grant No Z200722001)the Postgraduate Programme of Hubei Normal University of China (Grant No 2007D20)
文摘Using the method of the Jordan-Wigner transformation for solving different spin-spin correlation functions, we have investigated the generation of next-nearest-neighbouring entanglement in a one-dimensional quantum Ising spin chain with the Gaussian distribution impurities of exchange couplings and external magnetic fields taken into account. The maximal value of entanglement between the next-nearest-neighbouring qubits in the transverse Ising model was analysed in detail by varying the effectively controlled parameters such as interchange coupling, magnetic field and the system impurity. For such systems, where both exchange couplings and external magnetic field disorder appear, we show that it is possible to achieve next-nearest-neighbouring entanglement better than the previously discussed pure Ising spin chain case. We also show that the Gaussian distribution impurity can induce next-nearest-neighbouring entanglement, which can be used as a means to characterize quantum phase transition.
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2016YFA0300600 and 2016YFA0302104)the National Natural Science Foundation of China(Grant Nos.12074410,11934015,11975183,11947301,and 11774397)+2 种基金the Major Basic Research Program of Natural Science of Shaanxi Province,China(Grant Nos.2017KCT-12 and 2017ZDJC-32)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB33000000)the Fellowship of China Postdoctoral Science Foundation(Grant No.2020M680724).
文摘We construct an integrable quantum spin chain that includes the nearest-neighbor,next-nearest-neighbor,chiral threespin couplings,Dzyloshinsky–Moriya interactions and unparallel boundary magnetic fields.Although the interactions in bulk materials are isotropic,the spins nearby the boundary fields are polarized,which induce the anisotropic exchanging interactions of the first and last bonds.The U(1)symmetry of the system is broken because of the off-diagonal boundary reflections.Using the off-diagonal Bethe ansatz,we obtain an exact solution to the system.The inhomogeneous T–Q relation and Bethe ansatz equations are given explicitly.We also calculate the ground state energy.The method given in this paper provides a general way to construct new integrable models with certain interesting interactions.
基金Project supported by the National Natural Science Foundation of China (Grant No 10404039)the Foundation for the Author of National Excellent Doctoral Dissertation of China (Grant No 200524)Program for New Century Excellent Talents (NCET) of China (Grant No NCET-06-0920)
文摘Motivated by the wise idea of entanglement witness (EW), we present an inequivalent entanglement witness (IEEW) that can analogously classify certain eigenstates entangled in inequivalent ways under stochastic local operations and classical communication (SLOCC) in the Heisenberg spin chain. Since the IEEW is the absolute value of magnetization (M) that is a macroscopically measurable quantity, our conclusions provide a macroscopic method to detect inequivalent entanglement between microscopic spins, on the one hand, and clearly show that inequivalent entanglement can yield different macroscopic effects, on the other hand.
基金Project supported by the National Basic Research Program of China (Grant No. 2010CB923102)the Special Prophase Project on the National Basic Research Program of China (Grant No. 2011CB311807)the National Natural Science Foundation of China (Grant No. 11074199)
文摘We consider a qubit symmetrically and transversely coupled to an XY spin chain with Dzyaloshinsky-Moriya(DM) interaction in the presence of a transverse magnetic field.An analytical expression for the geometric phase of the qubit is obtained in the weak coupling limit.We find that the modification of the geometrical phase induced by the spin chain environment is greatly enhanced by DM interaction in the weak coupling limit around the quantum phase transition point of the spin chain.
基金Supported by the Research Program of Natural Science for Colleges and Universities in Jiangsu Province under Grant No.09KJB140009the National Natural Science Foundation under Grant No.10904104
基金The project supported by National Natural Science Foundation of China under Grant No. 10474104 and the National Fundamental Research Program of China under Grant No. 2001CB309310
基金Supported by the Natural Science Basic Research Plan in Henan Province of China under Grant No.2007140009
文摘Instanton configurations of (1+1)-dimensions in an antiferromagnetic biaxial-anisotropy-spin-ehain areobtained explicitly in the strong anisotropy limit,which interpolate between degenerate equilibrium orientations of theNeel vector along easy axis and are seen to be responsible for quantum tunneling.Macroscopic quantum coherence ofthe domain walls is demonstrated in terms of the instantons.
基金Supported by NSFC under Grants Nos.10874235,10934010,60978019NKBRSFC under Grants Nos.2006CB921400,2009CB930704,2010CB922904
文摘In this paper a stochastic series expansion quantum Monte Carlo algorithm is used to study a frustratedspin chain with diagonal next-nearest-neighbor interactions.The detailed balance conditions are carefully analyzed toimprove the efficiency of simulation process.As an application of this algothrim,the total magnetization,the staticstructure factor and spin-stiffness are calculated for a certain set of system parameters as a function of external fieldstrength.
基金Supported by the National Natural Science Foundation of China under Grant No. 10774108
文摘The bidirectional transfer of information can be realized in an open Heisenberg ferromagnetic spin chain.The information is encoded in the probability distributions of the states at two end spins. The relative entropy is used toevaluate the effective transmission of the probability. The evolution of the relative entropy shows a periodical behavior.The period is increased with increasing the length of the chain and the magnetic field while it decreases with increasingthe coupling strength.
基金Support from the National Natural Science Foundation of China under Grant No. 11074184
文摘The entanglement resonance in anisotropic spin-1/2 Heisenberg chains of different couplings is investigated when the nearest neighbor coupling is periodically modulated with external magnetic held. When the modulation frequency equals twice of the magnetic held, the entanglement resonance is larger than that at other modulation frequencies and decreases as the number of spins in the chain increases. When the modulation frequency equals the magnetic held, the entanglement resonance can be reduced to a quite low value by varying the couph'ng along z axis.