We calculate the concurrence and spin squeezing parameter of three atoms induced by a coherent field. It shows that when the mean numbers of photon of the field is very small, concurrence exhibits a certain kind of ap...We calculate the concurrence and spin squeezing parameter of three atoms induced by a coherent field. It shows that when the mean numbers of photon of the field is very small, concurrence exhibits a certain kind of approximative periodic vibration. With the increase of the mean numbers of photon, its periodicity will be interrupted. As for the relationship between the concurrence and spin squeezing, numeric result shows that under Dick model, spin squeezing serves as a sufficient but not necessary condition for concurrence.展开更多
We study the interaction between a single-mode quantized field and a quantum system composed of two qubits. We suppose that two qubits initially be prepared in the mixed and separable state, and study how entanglement...We study the interaction between a single-mode quantized field and a quantum system composed of two qubits. We suppose that two qubits initially be prepared in the mixed and separable state, and study how entanglement between two qubits arises in the course of evolution according to the Jaynes-Cummings type interaction with nonclassical radiation field. We also investigate the relation between entanglement and purity of qubit subsystem. We show that different photon statistics have different effects on the dynamical behavior of the qubit subsystem. When the qubits are initially prepared in the maximally mixed and separable state, for coherent state field we cannot find entanglement between two qubits; for squeezed state field entanglement between two qubits exists in several short period of time; for even and odd coherent state fields of large photon number, the dynamical behavior of the entanglement between two qubits shows collapse and revival phenomenon. For odd coherent state field of small photon number, the entanglement with both qubits initially prepared in maximally mixed state can be stronger than that with both qubits initially prepared in pure states. For fields of small photon number, the entanglement strongly depends on the states they are initially prepared in. For coherent state field, and odd and even coherent state fields of large photon number, the entanglement only depends on the purity of the initial state of qubit subsystem. We also show that during the evolution the unentangled state may be purer than the entangled state, and the maximum degree of entanglement may not occur at the time when the qubit subsystem is in the purist state.展开更多
We investigate the influence of the initial mixture of qubits and the dissipation on the entanglement transferfrom three-qubit Greenberger-Horne-Zeilinger(GHZ)and W state fields to three matter qubits,which are trappe...We investigate the influence of the initial mixture of qubits and the dissipation on the entanglement transferfrom three-qubit Greenberger-Horne-Zeilinger(GHZ)and W state fields to three matter qubits,which are trapped inthree spatially separated cavities.We find that at gt≈11.07,the entanglement transfer can be almost complete nomatter what state the qubits are initially prepared in.When the dissipation is taken into account,we tind that thespontaneous emission plays the similar role to the cavity damping in the entanglement transfer,and the decay rate ofthe GHZ state is larger than that of the W state.展开更多
The word “chudu” comes from Qu Yuan’s Li Sao “huang lan kui yu chu du xi, zhao ci yu yi jia ming”. The original meaning was the day of birth. After the Song Dynasty, the literati began to use it to refer to birth...The word “chudu” comes from Qu Yuan’s Li Sao “huang lan kui yu chu du xi, zhao ci yu yi jia ming”. The original meaning was the day of birth. After the Song Dynasty, the literati began to use it to refer to birthdays. By the end of the Ming Dynasty, they had been calling their birthdays “chudu” once they celebrated it and they were so keen on birthday celebrations. Gu Yanwu pointed out that the word “chudu” only fits “the old ministers （or the exiled ministers） who lamented the crash of the Yingcapital of the country of “Chu” such as Qu Yuan. At the same time, its use in Huang Zongxi’s and Wang Fuzhi’s birthday poems is also consistent with this context. The unique situation and mood of the adherents led them to be close to Qu Yuan and Wen Tianxiang, which bestowed “chudu” the special meaning. It is very suitable for the ministers who suffered the crash of their Dynasties or those who were exiled distantly to express their feelings about the old dynasties and old friends. After these people, Chen Yinke consciously acknowledged this layer of interpreting “chudu” and used it, which has not only enriched the connotation of “chudu”, but also extended its cultural life. From Qu Yuan to Wen Tianxiang, until Gu Yanwu, Huang Zongxi, Wang Fuzhi, and then to Chen Yinke, we can take a glimpse of the spiritual world of the Chinese adherents of Dynasties.展开更多
文摘We calculate the concurrence and spin squeezing parameter of three atoms induced by a coherent field. It shows that when the mean numbers of photon of the field is very small, concurrence exhibits a certain kind of approximative periodic vibration. With the increase of the mean numbers of photon, its periodicity will be interrupted. As for the relationship between the concurrence and spin squeezing, numeric result shows that under Dick model, spin squeezing serves as a sufficient but not necessary condition for concurrence.
文摘We study the interaction between a single-mode quantized field and a quantum system composed of two qubits. We suppose that two qubits initially be prepared in the mixed and separable state, and study how entanglement between two qubits arises in the course of evolution according to the Jaynes-Cummings type interaction with nonclassical radiation field. We also investigate the relation between entanglement and purity of qubit subsystem. We show that different photon statistics have different effects on the dynamical behavior of the qubit subsystem. When the qubits are initially prepared in the maximally mixed and separable state, for coherent state field we cannot find entanglement between two qubits; for squeezed state field entanglement between two qubits exists in several short period of time; for even and odd coherent state fields of large photon number, the dynamical behavior of the entanglement between two qubits shows collapse and revival phenomenon. For odd coherent state field of small photon number, the entanglement with both qubits initially prepared in maximally mixed state can be stronger than that with both qubits initially prepared in pure states. For fields of small photon number, the entanglement strongly depends on the states they are initially prepared in. For coherent state field, and odd and even coherent state fields of large photon number, the entanglement only depends on the purity of the initial state of qubit subsystem. We also show that during the evolution the unentangled state may be purer than the entangled state, and the maximum degree of entanglement may not occur at the time when the qubit subsystem is in the purist state.
基金The project supported by National Natural Science Foundation of China under Grant No.10374007
文摘We investigate the influence of the initial mixture of qubits and the dissipation on the entanglement transferfrom three-qubit Greenberger-Horne-Zeilinger(GHZ)and W state fields to three matter qubits,which are trapped inthree spatially separated cavities.We find that at gt≈11.07,the entanglement transfer can be almost complete nomatter what state the qubits are initially prepared in.When the dissipation is taken into account,we tind that thespontaneous emission plays the similar role to the cavity damping in the entanglement transfer,and the decay rate ofthe GHZ state is larger than that of the W state.
文摘The word “chudu” comes from Qu Yuan’s Li Sao “huang lan kui yu chu du xi, zhao ci yu yi jia ming”. The original meaning was the day of birth. After the Song Dynasty, the literati began to use it to refer to birthdays. By the end of the Ming Dynasty, they had been calling their birthdays “chudu” once they celebrated it and they were so keen on birthday celebrations. Gu Yanwu pointed out that the word “chudu” only fits “the old ministers （or the exiled ministers） who lamented the crash of the Yingcapital of the country of “Chu” such as Qu Yuan. At the same time, its use in Huang Zongxi’s and Wang Fuzhi’s birthday poems is also consistent with this context. The unique situation and mood of the adherents led them to be close to Qu Yuan and Wen Tianxiang, which bestowed “chudu” the special meaning. It is very suitable for the ministers who suffered the crash of their Dynasties or those who were exiled distantly to express their feelings about the old dynasties and old friends. After these people, Chen Yinke consciously acknowledged this layer of interpreting “chudu” and used it, which has not only enriched the connotation of “chudu”, but also extended its cultural life. From Qu Yuan to Wen Tianxiang, until Gu Yanwu, Huang Zongxi, Wang Fuzhi, and then to Chen Yinke, we can take a glimpse of the spiritual world of the Chinese adherents of Dynasties.
