Herein we have employed high-level multi-reference CASSCF and MS-CASPT2 electronic structure methods to systematically study the photochemical mechanism of intramolecularly hydrogen-bonded 2-（2＇-hydroxyphenyl）-4-me...Herein we have employed high-level multi-reference CASSCF and MS-CASPT2 electronic structure methods to systematically study the photochemical mechanism of intramolecularly hydrogen-bonded 2-（2＇-hydroxyphenyl）-4-methyloxazole. At the CASSCF level, we have optimized minima, conical intersections, minimum-energy reaction paths relevant to the excited-state intramolecular proton transfer （ESIPT）, rotation, photoisomerization, and the excited-state deactivation pathways. The energies of all structures and paths are refined by the MS-CASPT2 method. On the basis of the present results, we found that the ESIPT process in a conformer with the OH... N hydrogen bond is essentially barrierless process; whereas, the ESIPT process is inhibited in the other conformer with the OH... O hydrogen bond. The central single-bond rotation of the S1 enol species is energetically unfavorable due to a large barrier. In addition, the excited-state deactivation of the S1 keto species, as a result of the ultrafast ESIPT, is very efficient because of the existence of two easily-approached keto S1/S0 conical intersections. In stark contrast to the S1 keto species, the decay of the S1 enol species is almostly blocked. The present theoretical study contributes valuable knowledge to the understanding of photochemistry of similar intramolecularly hydrogen-bonded molecular and biological systems.展开更多
The excited state intramolecular proton transfer （ESIPT） coupled charge transfer of baicalein has been investigated using steady-state spectroscopic experiment and quantum chemistry calculations. The absence of the ...The excited state intramolecular proton transfer （ESIPT） coupled charge transfer of baicalein has been investigated using steady-state spectroscopic experiment and quantum chemistry calculations. The absence of the absorption peak from S1 excited state both in the experi-mental and calculated absorption spectra indicates that S1 is a dark state. The dark excited state S1 results in the very weak fluorescence of solid baicalein in the experiment. The fron- tier molecular orbital and the charge difference densities of baicalein show clearly that the S1 state is a charge-transfer state whereas the S2 state is a locally excited state. The only one stationary point on the potential energy profile of excited state suggests that the ESIPT reaction of baicalein is a barrierless process.展开更多
This paper analyses a system of two independent qubits off-resonantly coupled to a common non-Maxkovian reservoir at zero temperature. Compared with the results in Markovian reservoirs, we find that much higher values...This paper analyses a system of two independent qubits off-resonantly coupled to a common non-Maxkovian reservoir at zero temperature. Compared with the results in Markovian reservoirs, we find that much higher values of entanglement can be obtained for an initially factorized state of the two-qubit system. The maximal value of the entanglement increases as the detuning grows. Moreover, the entanglement induced by non-Maxkovian environments is more robust against the asymmetrical couplings between the two qubits and the reservoir. Based on this system, we also show that quantum state transfer can be implemented for arbitrary input states with high fidelity in the non-Markovian regime rather than the Markovian case in which only some particular input states can be successfully transferred.展开更多
We propose a new approach for quantum state transfer（QST） between atomic ensembles separately trapped in two distant cavities connected by an optical fiber via adiabatic passage. The three-level Λ-type atoms in eac...We propose a new approach for quantum state transfer（QST） between atomic ensembles separately trapped in two distant cavities connected by an optical fiber via adiabatic passage. The three-level Λ-type atoms in each ensemble dispersively interact with the nonresonant classical field and cavity mode. By choosing appropriate parameters of the system, the effective Hamiltonian describes two atomic ensembles interacting with ＂the same cavity mode＂ and has a dark state. Consequently, the QST between atomic ensembles can be implemented via adiabatic passage. Numerical calculations show that the scheme is robust against moderate fluctuations of the experimental parameters. In addition, the effect of decoherence can be suppressed effectively. The idea provides a scalable way to an atomic-ensemble-based quantum network, which may be reachable with currently available technology.展开更多
The quantum state transmission through the medium of high-dimensional many-particle system （boson or spinless fermion） is generally studied with a symmetry analysis. We discover that, if the spectrum of a Hamiltonia...The quantum state transmission through the medium of high-dimensional many-particle system （boson or spinless fermion） is generally studied with a symmetry analysis. We discover that, if the spectrum of a Hamiltonian matches the symmetry of a fermion or boson system in a certain fashion, a perfect quantum state transfer can be implemented without any operation on the medium with pre-engineered nearest neighbor （NN）. We also study a simple but realistic near half-filled tight-bindlng fermion system wlth uniform NN hopping integral. We show that an arbitrary many-particle state near the fermi surface can be perfectly transferred to its translational counterpart.展开更多
We propose and analyze an efficient high-dimensional quantum state transfer protocol in an XX coupling spin network with a hypercube structure or chain structure. Under free spin wave approximation, unitary evolution ...We propose and analyze an efficient high-dimensional quantum state transfer protocol in an XX coupling spin network with a hypercube structure or chain structure. Under free spin wave approximation, unitary evolution results in a perfect high-dimensional quantum swap operation requiring neither external manipulation nor weak coupling. Evolution time is independent of either distance between registers or dimensions of sent states, which can improve the computational efficiency. In the low temperature regime and thermodynamic limit, the decoherence caused by a noisy environment is studied with a model of an antiferromagnetic spin bath coupled to quantum channels via an Ising-type interaction. It is found that while the decoherence reduces the fidelity of state transfer, increasing intra-channel coupling can strongly suppress such an effect. These observations demonstrate the robustness of the proposed scheme.展开更多
The influence of the disturbance caused by the imperfection of the engineering coupling constants in the perfect state transfer is calculated. The results show that the fidelity for the perfect state transfer is serio...The influence of the disturbance caused by the imperfection of the engineering coupling constants in the perfect state transfer is calculated. The results show that the fidelity for the perfect state transfer is seriously affected by the errors occurring near the input and output spins. Such results are helpful for the realization of the perfect state transfer in the case where there exist errors in experiments.展开更多
An alternative scheme is proposed to transfer quantum states and prepare a quantum network in cavity QED. It is based on the interaction of a two-mode cavity field with a three-level V-type atom. In the scheme, the at...An alternative scheme is proposed to transfer quantum states and prepare a quantum network in cavity QED. It is based on the interaction of a two-mode cavity field with a three-level V-type atom. In the scheme, the atom-cavity field interaction is resonant, thus the time required to complete the quantum state transfer process is greatly shortened, which is very important in view of decoherence. Moreover, the present scheme does not require one mode of the cavities to be initially prepared in one-photon state, thus it is more experimentally feasible than the previous ones.展开更多
We present a scheme for transferring atomic entangled states via adiabatic passage. In the scheme, we use photons to achieve efficient quantum transmission among spatially distant atoms. The probability of the success...We present a scheme for transferring atomic entangled states via adiabatic passage. In the scheme, we use photons to achieve efficient quantum transmission among spatially distant atoms. The probability of the successful transferring quantum state approaches 1. Meanwhile, the scheme is robust against the effects of atomic spontaneous emission.展开更多
As a demonstration of the spectrum-parity matching condition （SPMC） for quantum state transfer, we investigate the propagation of single-magnon state in the Heisenberg chain in the confined external tangent magnetic...As a demonstration of the spectrum-parity matching condition （SPMC） for quantum state transfer, we investigate the propagation of single-magnon state in the Heisenberg chain in the confined external tangent magnetic field analytically and numerically. It shows that the initial Gaussian wave packet can be retrieved at the counterpart location near-perfectly over a longer distance if the dispersion relation of the system meets the SPMC approximately.展开更多
We propose schemes to realize quantum state transfer and prepare quantum entanglement in coupled cavity and cavity-fiber-cavity systems,respectively,by using the dressed state method.We first give the expression of pu...We propose schemes to realize quantum state transfer and prepare quantum entanglement in coupled cavity and cavity-fiber-cavity systems,respectively,by using the dressed state method.We first give the expression of pulses shape by using dressed states and then find a group of Gaussian pulses that are easy to realize in experiment to replace the ideal pulses by curve fitting.We also study the influence of some parameters fluctuation,atomic spontaneous emission,and photon leakage on fidelity.The results show that our schemes have good robustness.Because the atoms are trapped in different cavities,it is easy to perform different operations on different atoms.The proposed schemes have the potential applications in dressed states for distributed quantum information processing tasks.展开更多
We perform density functional theory calculations to investigate the polaron pair （charge transfer state） photo-generation in donor-acceptor oligomer methyl-capped （4,7- benzo[2,1,3]thiadiazole-2,6-（4,4-bis（2-eth...We perform density functional theory calculations to investigate the polaron pair （charge transfer state） photo-generation in donor-acceptor oligomer methyl-capped （4,7- benzo[2,1,3]thiadiazole-2,6-（4,4-bis（2-ethylhexyl）-4H-cyclopent a[1,2-b;3,4-b＇]dithiophene-4, 7-benzo[2,1,3]thiadiazole） （CPDTBT）. Results show that effective photo-generation of charge transfer state can happen in CPDTBT dimer when the group 4,7-benzo[2,1,3]thiadiazole （BT） in one monomer deviates against the conjugated plane （onset torsion angle is about 20°）. The lower excitation energy （530 nm） can only generate the intramolecular excitonic state, while the higher excitation energy （370 nm） can generate the intermolecular charge transfer state, in good agreement with the experiment. Moreover, the mechanism of charge separation in CPDTBT oligorners is discussed.展开更多
We suggest a method for transferring an unknown quantum state. In this method the sender Alice first applies a controlled-not operation on the particle in the unknown quantum state and an ancillary particle which she ...We suggest a method for transferring an unknown quantum state. In this method the sender Alice first applies a controlled-not operation on the particle in the unknown quantum state and an ancillary particle which she wants to send to the receiver Bob. Then she sends the ancillary particle to Bob. When Alice is informed by Bob that the ancillary particle is received, she performs a local measurement on her particle and sends Bob the outcome of the local measurement via a classical channel. Depending on the outcome Bob can restore the unknown quantum state, which Alice destroyed, on the ancillary particle successfully. As an application of this method we propose a quantum secure direct communication protocol. By introducing the decoy qubits the security of the scheme is guaranteed.展开更多
We propose schemes to prepare n-atom Greenberger-Horn-Zeilinger （GHZ） state via two-sided cavities interacting with single-photon pulses, and achieve quantum state transfer （QST） from one atom to another atom. Ent...We propose schemes to prepare n-atom Greenberger-Horn-Zeilinger （GHZ） state via two-sided cavities interacting with single-photon pulses, and achieve quantum state transfer （QST） from one atom to another atom. Entanglement particle pair and the control of coupling between qu bits are of no need in the QST process. Some practical quantum noises only decrease the success probabilities of the schemes but have no influence on the fidelity of prepared state. In addition, the success probabilities of our schemes are close to unity in the ideal case.展开更多
Transmitting quantum states by channels of analogous Bell states is studied in this paper. We analyze the transmitting process. constructed the probabilitic unitary operator, and gain the largest successful transfer q...Transmitting quantum states by channels of analogous Bell states is studied in this paper. We analyze the transmitting process. constructed the probabilitic unitary operator, and gain the largest successful transfer quantum state probability.展开更多
We investigate the effect of phase shift on the perfect state transfer through two parallel one-dimensional ring-shaped spin chains. We find that the total success probability can be significantly enhanced by phase sh...We investigate the effect of phase shift on the perfect state transfer through two parallel one-dimensional ring-shaped spin chains. We find that the total success probability can be significantly enhanced by phase shift control when the communication channel consists of two odd chains. The average time to gain unit success probability is discussed, showing that a proper phase shift can be used to enhance the efficiency of state transmission.展开更多
We propose and analyze a robust quantum state transfer protocol through a scalable quantum data bus that consists of a network of controlled dissipative modules.In particular,we first demonstrate the ability to achiev...We propose and analyze a robust quantum state transfer protocol through a scalable quantum data bus that consists of a network of controlled dissipative modules.In particular,we first demonstrate the ability to achieve perfect state transfer between two distinct quantum sites which are adiabatically coupled to the data bus in non-dissipative situation.We then consider the role of dissipation in adiabatic quantum state transfer via using Born–Markov master equation in the standard Lindblad form.Numerical simulation shows that the dissipation effect on the quality of transmission can be suppressed by engineering the network couplings of data bus properly.展开更多
The quantum state transfer between two membranes in coupled cavities is studied when the system is surrounded by non-Markovian environments. An analytical approach for describing non-Markovian memory effects that impa...The quantum state transfer between two membranes in coupled cavities is studied when the system is surrounded by non-Markovian environments. An analytical approach for describing non-Markovian memory effects that impact on the state transfer between distant membranes is presented. We show that quantum state transfer can be implemented with high efficiency by utilizing the experimental spectral density, and the performance of state transfer in non-Markovian environments is much better than that in Markovian environments, especially when the tunneling strength between the two cavities is not very large.展开更多
Based on the Wu's scheme[C.F.Wu,J.L.Chen,L.C.Kwekl,and C.H.Ohel,Phys.Rev.A 73(2006)012310],we prepare the general N-qubit W state.We find that the concurrence of two qubits in general N-qubit Wstate is only relate...Based on the Wu's scheme[C.F.Wu,J.L.Chen,L.C.Kwekl,and C.H.Ohel,Phys.Rev.A 73(2006)012310],we prepare the general N-qubit W state.We find that the concurrence of two qubits in general N-qubit Wstate is only related to their coefficients and we successfully apply the general N-qubit W state to quantum state transferand quantum state prepare like that in two-qubit system.展开更多
This paper proposes a scheme for transferring an N-atom state between two distant cavities via an optical fiber. The scheme is based on adiabatic passage along a dark state. In the scheme, all the atoms are always in ...This paper proposes a scheme for transferring an N-atom state between two distant cavities via an optical fiber. The scheme is based on adiabatic passage along a dark state. In the scheme, all the atoms are always in ground state, the field mode of the fiber remains in vacuum state, and the field mode of the cavities being excited can be negligible under certain conditions. Therefore, the scheme is very robust against decoherence. The successful probability of implementing the quantum state transfer increases with increasing number of atoms. Furthermore, the interaction time does not need to be accurately adjusted as long as the adiabaticity condition is fulfilled.展开更多
文摘Herein we have employed high-level multi-reference CASSCF and MS-CASPT2 electronic structure methods to systematically study the photochemical mechanism of intramolecularly hydrogen-bonded 2-（2＇-hydroxyphenyl）-4-methyloxazole. At the CASSCF level, we have optimized minima, conical intersections, minimum-energy reaction paths relevant to the excited-state intramolecular proton transfer （ESIPT）, rotation, photoisomerization, and the excited-state deactivation pathways. The energies of all structures and paths are refined by the MS-CASPT2 method. On the basis of the present results, we found that the ESIPT process in a conformer with the OH... N hydrogen bond is essentially barrierless process; whereas, the ESIPT process is inhibited in the other conformer with the OH... O hydrogen bond. The central single-bond rotation of the S1 enol species is energetically unfavorable due to a large barrier. In addition, the excited-state deactivation of the S1 keto species, as a result of the ultrafast ESIPT, is very efficient because of the existence of two easily-approached keto S1/S0 conical intersections. In stark contrast to the S1 keto species, the decay of the S1 enol species is almostly blocked. The present theoretical study contributes valuable knowledge to the understanding of photochemistry of similar intramolecularly hydrogen-bonded molecular and biological systems.
基金ACKNOWLEDGMENTS This work was supported by the National Natural Science Foundation of China （No.61137005 and No.10974023）, the Program for Liaoning Excellent Talents in University （No.LJQ2012002）, and the Program for New Century Excellent Talents in University （No.NCET-12-0077）.
文摘The excited state intramolecular proton transfer （ESIPT） coupled charge transfer of baicalein has been investigated using steady-state spectroscopic experiment and quantum chemistry calculations. The absence of the absorption peak from S1 excited state both in the experi-mental and calculated absorption spectra indicates that S1 is a dark state. The dark excited state S1 results in the very weak fluorescence of solid baicalein in the experiment. The fron- tier molecular orbital and the charge difference densities of baicalein show clearly that the S1 state is a charge-transfer state whereas the S2 state is a locally excited state. The only one stationary point on the potential energy profile of excited state suggests that the ESIPT reaction of baicalein is a barrierless process.
基金supported by the National Natural Science Foundation of China (Grant No. 11074072)the Innovation Foundation for Postgraduate of Hunan Province of China (Grant No. CX2010B213)
文摘This paper analyses a system of two independent qubits off-resonantly coupled to a common non-Maxkovian reservoir at zero temperature. Compared with the results in Markovian reservoirs, we find that much higher values of entanglement can be obtained for an initially factorized state of the two-qubit system. The maximal value of the entanglement increases as the detuning grows. Moreover, the entanglement induced by non-Maxkovian environments is more robust against the asymmetrical couplings between the two qubits and the reservoir. Based on this system, we also show that quantum state transfer can be implemented for arbitrary input states with high fidelity in the non-Markovian regime rather than the Markovian case in which only some particular input states can be successfully transferred.
基金Project supported by the Funding(type B)from the Fujian Education Department,China(Grant No.JB13261)
文摘We propose a new approach for quantum state transfer（QST） between atomic ensembles separately trapped in two distant cavities connected by an optical fiber via adiabatic passage. The three-level Λ-type atoms in each ensemble dispersively interact with the nonresonant classical field and cavity mode. By choosing appropriate parameters of the system, the effective Hamiltonian describes two atomic ensembles interacting with ＂the same cavity mode＂ and has a dark state. Consequently, the QST between atomic ensembles can be implemented via adiabatic passage. Numerical calculations show that the scheme is robust against moderate fluctuations of the experimental parameters. In addition, the effect of decoherence can be suppressed effectively. The idea provides a scalable way to an atomic-ensemble-based quantum network, which may be reachable with currently available technology.
基金The project supported by National Natural Science Foundation of China under Grant Nos. 90203018, 10474104, and 10447133, and the Knowledge Innovation Program （KIP） of the Chinese Academy of Sciences, the National Fundamental Research Program of China under Grant No. 2001CB309310
文摘The quantum state transmission through the medium of high-dimensional many-particle system （boson or spinless fermion） is generally studied with a symmetry analysis. We discover that, if the spectrum of a Hamiltonian matches the symmetry of a fermion or boson system in a certain fashion, a perfect quantum state transfer can be implemented without any operation on the medium with pre-engineered nearest neighbor （NN）. We also study a simple but realistic near half-filled tight-bindlng fermion system wlth uniform NN hopping integral. We show that an arbitrary many-particle state near the fermi surface can be perfectly transferred to its translational counterpart.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11175094 and 91221205)the National Basic Research Program of China(Grant No.2011CB9216002)support of Center of Atomic and Molecular Nanoscience of Tsinghua University,China
文摘We propose and analyze an efficient high-dimensional quantum state transfer protocol in an XX coupling spin network with a hypercube structure or chain structure. Under free spin wave approximation, unitary evolution results in a perfect high-dimensional quantum swap operation requiring neither external manipulation nor weak coupling. Evolution time is independent of either distance between registers or dimensions of sent states, which can improve the computational efficiency. In the low temperature regime and thermodynamic limit, the decoherence caused by a noisy environment is studied with a model of an antiferromagnetic spin bath coupled to quantum channels via an Ising-type interaction. It is found that while the decoherence reduces the fidelity of state transfer, increasing intra-channel coupling can strongly suppress such an effect. These observations demonstrate the robustness of the proposed scheme.
基金Project supported by the National Natural Science Foundation of China （Grant No 10374010）.Acknowledgement Liu Dan would like to thank Professor Long Gui- Lu of Tsinghua University for helpful discussions.
文摘The influence of the disturbance caused by the imperfection of the engineering coupling constants in the perfect state transfer is calculated. The results show that the fidelity for the perfect state transfer is seriously affected by the errors occurring near the input and output spins. Such results are helpful for the realization of the perfect state transfer in the case where there exist errors in experiments.
基金The project supported by National Natural Science Foundation of China under Grant Nos. 10225421 and 10674025
文摘An alternative scheme is proposed to transfer quantum states and prepare a quantum network in cavity QED. It is based on the interaction of a two-mode cavity field with a three-level V-type atom. In the scheme, the atom-cavity field interaction is resonant, thus the time required to complete the quantum state transfer process is greatly shortened, which is very important in view of decoherence. Moreover, the present scheme does not require one mode of the cavities to be initially prepared in one-photon state, thus it is more experimentally feasible than the previous ones.
基金The project supported by National Natural Science Foundation of China under Grant No. 10574022 and the Natural Science Foundaation of Fujian Province under Grant No. Z0512006
文摘We present a scheme for transferring atomic entangled states via adiabatic passage. In the scheme, we use photons to achieve efficient quantum transmission among spatially distant atoms. The probability of the successful transferring quantum state approaches 1. Meanwhile, the scheme is robust against the effects of atomic spontaneous emission.
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
文摘As a demonstration of the spectrum-parity matching condition （SPMC） for quantum state transfer, we investigate the propagation of single-magnon state in the Heisenberg chain in the confined external tangent magnetic field analytically and numerically. It shows that the initial Gaussian wave packet can be retrieved at the counterpart location near-perfectly over a longer distance if the dispersion relation of the system meets the SPMC approximately.
基金Project supported by the National Natural Science Foundation of China(Grant No.11804308).
文摘We propose schemes to realize quantum state transfer and prepare quantum entanglement in coupled cavity and cavity-fiber-cavity systems,respectively,by using the dressed state method.We first give the expression of pulses shape by using dressed states and then find a group of Gaussian pulses that are easy to realize in experiment to replace the ideal pulses by curve fitting.We also study the influence of some parameters fluctuation,atomic spontaneous emission,and photon leakage on fidelity.The results show that our schemes have good robustness.Because the atoms are trapped in different cavities,it is easy to perform different operations on different atoms.The proposed schemes have the potential applications in dressed states for distributed quantum information processing tasks.
基金supported by the National Natural Science Foundation of China (No.21473092)the Jiangsu Province Production and Joint Innovation Fund-Prospective Joint Research Project (No. BY2014007-01)
文摘We perform density functional theory calculations to investigate the polaron pair （charge transfer state） photo-generation in donor-acceptor oligomer methyl-capped （4,7- benzo[2,1,3]thiadiazole-2,6-（4,4-bis（2-ethylhexyl）-4H-cyclopent a[1,2-b;3,4-b＇]dithiophene-4, 7-benzo[2,1,3]thiadiazole） （CPDTBT）. Results show that effective photo-generation of charge transfer state can happen in CPDTBT dimer when the group 4,7-benzo[2,1,3]thiadiazole （BT） in one monomer deviates against the conjugated plane （onset torsion angle is about 20°）. The lower excitation energy （530 nm） can only generate the intramolecular excitonic state, while the higher excitation energy （370 nm） can generate the intermolecular charge transfer state, in good agreement with the experiment. Moreover, the mechanism of charge separation in CPDTBT oligorners is discussed.
基金The project supported by the National Natural Science Foundation of China under Grant No. 10671054 and the Natural Science Foundation of Hebei Province under Grant Nos. A2004000141 and A2005000140
文摘We suggest a method for transferring an unknown quantum state. In this method the sender Alice first applies a controlled-not operation on the particle in the unknown quantum state and an ancillary particle which she wants to send to the receiver Bob. Then she sends the ancillary particle to Bob. When Alice is informed by Bob that the ancillary particle is received, she performs a local measurement on her particle and sends Bob the outcome of the local measurement via a classical channel. Depending on the outcome Bob can restore the unknown quantum state, which Alice destroyed, on the ancillary particle successfully. As an application of this method we propose a quantum secure direct communication protocol. By introducing the decoy qubits the security of the scheme is guaranteed.
基金supported by National Natural Science Foundation of China under Grant No.10574022the Natural Science Foundation of Fujian Province of China under Grant Nos.A0410016 and 2006J0230Funds of Education Committee of Fujian Province under Grant No.JB05334
文摘We propose schemes to prepare n-atom Greenberger-Horn-Zeilinger （GHZ） state via two-sided cavities interacting with single-photon pulses, and achieve quantum state transfer （QST） from one atom to another atom. Entanglement particle pair and the control of coupling between qu bits are of no need in the QST process. Some practical quantum noises only decrease the success probabilities of the schemes but have no influence on the fidelity of prepared state. In addition, the success probabilities of our schemes are close to unity in the ideal case.
基金National Natural Science Foundation of China under Grant No.10575017
文摘Transmitting quantum states by channels of analogous Bell states is studied in this paper. We analyze the transmitting process. constructed the probabilitic unitary operator, and gain the largest successful transfer quantum state probability.
基金Supported by National Natural Science Foundation of China under Grant Nos.11005099,60677044the Fundamental Research Funds for the Central Universities under Grant No.201013037
文摘We investigate the effect of phase shift on the perfect state transfer through two parallel one-dimensional ring-shaped spin chains. We find that the total success probability can be significantly enhanced by phase shift control when the communication channel consists of two odd chains. The average time to gain unit success probability is discussed, showing that a proper phase shift can be used to enhance the efficiency of state transmission.
基金Supported by the Shandong Provincial Natural Science Foundation under Grant No.ZR2016AM18the National Natural Science Foundation of China under Grant No.61675118。
文摘We propose and analyze a robust quantum state transfer protocol through a scalable quantum data bus that consists of a network of controlled dissipative modules.In particular,we first demonstrate the ability to achieve perfect state transfer between two distinct quantum sites which are adiabatically coupled to the data bus in non-dissipative situation.We then consider the role of dissipation in adiabatic quantum state transfer via using Born–Markov master equation in the standard Lindblad form.Numerical simulation shows that the dissipation effect on the quality of transmission can be suppressed by engineering the network couplings of data bus properly.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11704205,11704026,21773131,and 11574167)China Postdoctoral Science Foundation(Grant No.2018M632437)+1 种基金the Natural Science Foundation of Ningbo City(Grant No.2018A610199)K C Wong Magna Fund in Ningbo University,China
文摘The quantum state transfer between two membranes in coupled cavities is studied when the system is surrounded by non-Markovian environments. An analytical approach for describing non-Markovian memory effects that impact on the state transfer between distant membranes is presented. We show that quantum state transfer can be implemented with high efficiency by utilizing the experimental spectral density, and the performance of state transfer in non-Markovian environments is much better than that in Markovian environments, especially when the tunneling strength between the two cavities is not very large.
基金National Natural Science Foundation of China under Grant Nos.10575017 and 10547106
文摘Based on the Wu's scheme[C.F.Wu,J.L.Chen,L.C.Kwekl,and C.H.Ohel,Phys.Rev.A 73(2006)012310],we prepare the general N-qubit W state.We find that the concurrence of two qubits in general N-qubit Wstate is only related to their coefficients and we successfully apply the general N-qubit W state to quantum state transferand quantum state prepare like that in two-qubit system.
基金supported by the Science Foundation of Educational Committee of Fujian Province (Grant No JB06042)
文摘This paper proposes a scheme for transferring an N-atom state between two distant cavities via an optical fiber. The scheme is based on adiabatic passage along a dark state. In the scheme, all the atoms are always in ground state, the field mode of the fiber remains in vacuum state, and the field mode of the cavities being excited can be negligible under certain conditions. Therefore, the scheme is very robust against decoherence. The successful probability of implementing the quantum state transfer increases with increasing number of atoms. Furthermore, the interaction time does not need to be accurately adjusted as long as the adiabaticity condition is fulfilled.
