Considering a quantum model consisting of two effective two-level atoms and a single-mode cavity, this paper investigates the entanglement dynamics between the two atoms, and studies the effect of the Stark shift on t...Considering a quantum model consisting of two effective two-level atoms and a single-mode cavity, this paper investigates the entanglement dynamics between the two atoms, and studies the effect of the Stark shift on the entanglement. The results show that, on the one hand the atom-atom entanglement evolves periodically with time and the periods are affected by the Stark shift; on the other hand, the two atoms are not disentangled at any time when the Stark shift is considered, and for large values of the Stark shift parameter, the two atoms can remain in a stationary entangled state. In addition, for the initially partially entangled atomic state, the atom-atom entanglement can be greatly enhanced due to the presence of Stark shift. These properties show that the Stark shift can be used to control entanglement between two atoms.展开更多
Wavelength-dependent AC Stark shifts and magic wavelengths of the terahertz clock transitions between the metastable triplet states 6s5d3D1 and 6s5d3D2are investigated with considering the optical lattice trapping of ...Wavelength-dependent AC Stark shifts and magic wavelengths of the terahertz clock transitions between the metastable triplet states 6s5d3D1 and 6s5d3D2are investigated with considering the optical lattice trapping of barium atoms with the linearly polarized laser. The trap depths and the slopes of light shift difference with distinct magic wavelengths of the optical lattices are also discussed in detail. Several potentially suitable working points for the optical lattice trapping laser are recommended and selected from these magic wavelengths.展开更多
The exciton Stark shift and polarization in hemispherical quantum dots(HQDs)each as a function of strength and orientation of applied electric field are theoretically investigated by an exact diagonalization method.A ...The exciton Stark shift and polarization in hemispherical quantum dots(HQDs)each as a function of strength and orientation of applied electric field are theoretically investigated by an exact diagonalization method.A highly anisotropic Stark redshift of exciton energy is found.As the electric field is rotated from Voigt to Faraday geometry,the redshift of exciton energy monotonically decreases.This is because the asymmetric geometric shape of the hemispherical quantum dot restrains the displacement of the wave function to the higher orbital state in response to electric field along Faraday geometry.A redshift of hole energy is found all the time while a transition of electron energy from this redshift to a blueshift is found as the field is rotated from Voigt to Faraday geometry.Taking advantage of the diminishing of Stark effect along Faraday geometry,the hemispherical shapes can be used to improve significantly the radiative recombination efficiency of the polar optoelectronic devices if the strong internal polarized electric field is along Faraday geometry.展开更多
Ac-Stark shift of atom levels is caused by an ac-electromagnetic field. As an electromagnetic wave, laser light does induce ac-Stark shift. It is proved experimentally that if the light is linearly polarized, the dyna...Ac-Stark shift of atom levels is caused by an ac-electromagnetic field. As an electromagnetic wave, laser light does induce ac-Stark shift. It is proved experimentally that if the light is linearly polarized, the dynamic polarizability changes with polarization direction. The polarization direction of the linearly-polarized laser is tuned by 720°, and the ac-Stark shifts of the 4S1/2,m=±1/2→3D5/2,m=±1/2 clock transitions in ^40Ca^＋ are measured in steps of 10°. The frequency shifts change with laser polarization in a periodical manner and have values opposite to each other.展开更多
The time evolution of the linear entropy of an atom in k-photon Jaynes-Cummings model is investigatedtaking into consideration Stark shift and Kerr-like medium. The effect of both the Stark shift and Kerr-like medium ...The time evolution of the linear entropy of an atom in k-photon Jaynes-Cummings model is investigatedtaking into consideration Stark shift and Kerr-like medium. The effect of both the Stark shift and Kerr-like medium onthe linear entropy is analyzed using a numerical technique for the field initially in coherent state and in even coherentstate. The results show that the presence of the Kerr-like medium and Stark shift has an important effect on theproperties of the entropy and entanglement. It is also shown that the setting of the initial state plays a significant rolein the evolution of the linear entropy and entanglement.展开更多
We construct a power enhancement cavity to form an optical lattice in an ytterbium optical clock.It is demonstrated that the intra-cavity lattice power can be increased by about 45 times,and the trap depth can be as l...We construct a power enhancement cavity to form an optical lattice in an ytterbium optical clock.It is demonstrated that the intra-cavity lattice power can be increased by about 45 times,and the trap depth can be as large as 1400Er when laser light with a power of only 0.6 W incident to the lattice cavity.Such high trap depths are the key to accurate evaluation of the lattice-induced light shift with an uncertainty down to~1×10-18.By probing the ytterbium atoms trapped in the power-enhanced optical lattice,we obtain a 4.3 Hz-linewidth Rabi spectrum,which is then used to feedback to the clock laser for the close loop operation of the optical lattice clock.We evaluate the density shift of the Yb optical lattice clock based on interleaving measurements,which is-0.46(62)mHz.This result is smaller compared to the density shift of our first Yb optical clock without lattice power enhancement cavity mainly due to a larger lattice diameter of 344μm.展开更多
Infrared signal detection is widely used in many fields.Due to the detection principle,however,the accuracy and range of detection are limited.Thanks to the ultra stability of the^(87)Sr optical lattice clock,external...Infrared signal detection is widely used in many fields.Due to the detection principle,however,the accuracy and range of detection are limited.Thanks to the ultra stability of the^(87)Sr optical lattice clock,external infrared electromagnetic wave disturbances can be responded to.Utilizing the ac Stark shift of the clock transition,we propose a new method to detect infrared signals.According to our calculations,the theoretical detection accuracy in the vicinity of its resonance band of 2.6μm can reach the order of 10-14W,while the minimum detectable signal of common detectors is on the order of 10^(-10)W.展开更多
基金supported by the Young Scientists Fund of the National Natural Science Foundation of China (Grant No. 10905028)the Natural Science Foundation of Hunan Province of China (Grant No. 07JJ3013)+1 种基金the Program for Science and Technology Department of Henan Province of China (Grant No. 102300410050)the Foundation of Hunan Provincial Education Department of China (Grant No. 06A038)
文摘Considering a quantum model consisting of two effective two-level atoms and a single-mode cavity, this paper investigates the entanglement dynamics between the two atoms, and studies the effect of the Stark shift on the entanglement. The results show that, on the one hand the atom-atom entanglement evolves periodically with time and the periods are affected by the Stark shift; on the other hand, the two atoms are not disentangled at any time when the Stark shift is considered, and for large values of the Stark shift parameter, the two atoms can remain in a stationary entangled state. In addition, for the initially partially entangled atomic state, the atom-atom entanglement can be greatly enhanced due to the presence of Stark shift. These properties show that the Stark shift can be used to control entanglement between two atoms.
基金Project supported by the Science Fund from the Shaanxi Provincial Education Department,China(Grant No.14JK1402)
文摘Wavelength-dependent AC Stark shifts and magic wavelengths of the terahertz clock transitions between the metastable triplet states 6s5d3D1 and 6s5d3D2are investigated with considering the optical lattice trapping of barium atoms with the linearly polarized laser. The trap depths and the slopes of light shift difference with distinct magic wavelengths of the optical lattices are also discussed in detail. Several potentially suitable working points for the optical lattice trapping laser are recommended and selected from these magic wavelengths.
文摘The exciton Stark shift and polarization in hemispherical quantum dots(HQDs)each as a function of strength and orientation of applied electric field are theoretically investigated by an exact diagonalization method.A highly anisotropic Stark redshift of exciton energy is found.As the electric field is rotated from Voigt to Faraday geometry,the redshift of exciton energy monotonically decreases.This is because the asymmetric geometric shape of the hemispherical quantum dot restrains the displacement of the wave function to the higher orbital state in response to electric field along Faraday geometry.A redshift of hole energy is found all the time while a transition of electron energy from this redshift to a blueshift is found as the field is rotated from Voigt to Faraday geometry.Taking advantage of the diminishing of Stark effect along Faraday geometry,the hemispherical shapes can be used to improve significantly the radiative recombination efficiency of the polar optoelectronic devices if the strong internal polarized electric field is along Faraday geometry.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.91336211,11634013,11622434,11474318,and 11504094)the Chinese Academy of Sciences(Grant No.XDB21030000)
文摘Ac-Stark shift of atom levels is caused by an ac-electromagnetic field. As an electromagnetic wave, laser light does induce ac-Stark shift. It is proved experimentally that if the light is linearly polarized, the dynamic polarizability changes with polarization direction. The polarization direction of the linearly-polarized laser is tuned by 720°, and the ac-Stark shifts of the 4S1/2,m=±1/2→3D5/2,m=±1/2 clock transitions in ^40Ca^＋ are measured in steps of 10°. The frequency shifts change with laser polarization in a periodical manner and have values opposite to each other.
基金Supported by the National Natural Science Foundation of China under Grant Nos. 10674038, 10604042National Basic Research Program of China under Grant No. 2006CB302901
文摘The time evolution of the linear entropy of an atom in k-photon Jaynes-Cummings model is investigatedtaking into consideration Stark shift and Kerr-like medium. The effect of both the Stark shift and Kerr-like medium onthe linear entropy is analyzed using a numerical technique for the field initially in coherent state and in even coherentstate. The results show that the presence of the Kerr-like medium and Stark shift has an important effect on theproperties of the entropy and entanglement. It is also shown that the setting of the initial state plays a significant rolein the evolution of the linear entropy and entanglement.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12334020 and 11927810)the National Key Research and Development Program of China(Grant No.2022YFB3904001).
文摘We construct a power enhancement cavity to form an optical lattice in an ytterbium optical clock.It is demonstrated that the intra-cavity lattice power can be increased by about 45 times,and the trap depth can be as large as 1400Er when laser light with a power of only 0.6 W incident to the lattice cavity.Such high trap depths are the key to accurate evaluation of the lattice-induced light shift with an uncertainty down to~1×10-18.By probing the ytterbium atoms trapped in the power-enhanced optical lattice,we obtain a 4.3 Hz-linewidth Rabi spectrum,which is then used to feedback to the clock laser for the close loop operation of the optical lattice clock.We evaluate the density shift of the Yb optical lattice clock based on interleaving measurements,which is-0.46(62)mHz.This result is smaller compared to the density shift of our first Yb optical clock without lattice power enhancement cavity mainly due to a larger lattice diameter of 344μm.
基金Project supported by the National Natural Science Foundation of China (Grant No.12274045)。
文摘Infrared signal detection is widely used in many fields.Due to the detection principle,however,the accuracy and range of detection are limited.Thanks to the ultra stability of the^(87)Sr optical lattice clock,external infrared electromagnetic wave disturbances can be responded to.Utilizing the ac Stark shift of the clock transition,we propose a new method to detect infrared signals.According to our calculations,the theoretical detection accuracy in the vicinity of its resonance band of 2.6μm can reach the order of 10-14W,while the minimum detectable signal of common detectors is on the order of 10^(-10)W.
