We investigate the quantum motion of two ions stored in a Paul trap and interacting with a time-periodic laser field. In the pseudopotential approximation and large detuning condition, we find that the relative motion...We investigate the quantum motion of two ions stored in a Paul trap and interacting with a time-periodic laser field. In the pseudopotential approximation and large detuning condition, we find that the relative motion is independent of the laser field, but the exact centre-of-mass motion is closely related to the laser field. By adjusting the laser intensity and frequency, we can well control the quantum motion of the centre-of-mass. We illustrate some physical properties described by the centre-of-mass states, such as the squeezed coherent property, the widths and heights of the wavepackets of probability density, the classical-quantum correspondence, the resonance ladders of expectation energy and the transition probabilities between time-dependent quantum levels.展开更多
The 27Al＋ ion optical clock is one of the most attractive optical clocks due to its own advantages such as low black-body radiation shift at room temperature and insensitivity to the magnetic drift. However, it canno...The 27Al＋ ion optical clock is one of the most attractive optical clocks due to its own advantages such as low black-body radiation shift at room temperature and insensitivity to the magnetic drift. However, it cannot be laser-cooled directly in the absence of 167nm laser to date. This problem can be solved by sympathetic cooling. In this work, a linear Paul trap is used to trap both 40Ca＋ and 27A1＋ ions simultaneously, and a single Dopplercooled 40Ca＋ ion is employed to sympathetically cool a single 27A1＋ ion. Thus a ＇bright-dark＇ two-ion crystal has been successfully synthesized. The temperature of the crystal has been estimated to be about 7mK by measuring the ratio of carrier and sideband spectral intensities. Finally, the dark ion is proved to be an 27Al＋ ion by precise measuring of the ion crystal＇s secular motion frequency, which means that it is a great step for our 2Z Al＋ quantum logic clock.展开更多
The effect of double frequency oftrap fieldφ=U-V1 cosΩt-V2 cos 2Ωt in a Paul trap can be described exactly by using a function series expansion to solve the corresponding Mathieu equation.The stability regions of a...The effect of double frequency oftrap fieldφ=U-V1 cosΩt-V2 cos 2Ωt in a Paul trap can be described exactly by using a function series expansion to solve the corresponding Mathieu equation.The stability regions of a trapped ion are plotted and some meaningful physical results are shown.展开更多
We have studied the quantum and classical motions of a single Paul trapped ion interacting with a timeperiodic laser field. By using the test-function method, we construct n exact solutions of quantum dynamics that de...We have studied the quantum and classical motions of a single Paul trapped ion interacting with a timeperiodic laser field. By using the test-function method, we construct n exact solutions of quantum dynamics that describe the generalized squeezed coherent states with the expectation orbits being the corresponding classical ones. The spacetime evolutions of the exact probability densities show some wavepacket trains. It is demonstrated analytically that by adjusting the laser intensity and frequency, we can control the center motions of the wavepacket trains. We also discuss the other physical properties such as the expectation value of energy, the widths and heights of the wavepackets, and the resonance loss of stability.展开更多
The 7Li＋ ion is one of the most important candidates for verifying QED theory and obtaining the precise value of the fine-structure constant ~. However, direct laser cooling of trapped Li＋ ions will lead to strong b...The 7Li＋ ion is one of the most important candidates for verifying QED theory and obtaining the precise value of the fine-structure constant ~. However, direct laser cooling of trapped Li＋ ions will lead to strong background fluorescence which will influence the spectrum detection. The sympathetic cooling technique is a good choice to solve the problem. In this work, we report sympathetic cooling of 7 Li＋ ions to few mK using 40Ca＋ ions in a linear Paul trap. A mixed ion crystal of 40Ca＋ ions and 7Li＋ ions are obtained. We also analyze the motion frequency spectra of pure 40 Ca＋ ions and mixed ions.展开更多
基金Project supported by the National Natural Science Foundation of China （Grant Nos 10575034 and 10275023）, and the Science Foundation of the Laboratory of Magnetic Resonance and Atomic and Molecular Physics, China （Grant No T152504）.
文摘We investigate the quantum motion of two ions stored in a Paul trap and interacting with a time-periodic laser field. In the pseudopotential approximation and large detuning condition, we find that the relative motion is independent of the laser field, but the exact centre-of-mass motion is closely related to the laser field. By adjusting the laser intensity and frequency, we can well control the quantum motion of the centre-of-mass. We illustrate some physical properties described by the centre-of-mass states, such as the squeezed coherent property, the widths and heights of the wavepackets of probability density, the classical-quantum correspondence, the resonance ladders of expectation energy and the transition probabilities between time-dependent quantum levels.
基金Supported by the National High Technology Research and Development Program of China under Grant No 2012AA120701the National Natural Science Foundation of China under Grant No 11174326
文摘The 27Al＋ ion optical clock is one of the most attractive optical clocks due to its own advantages such as low black-body radiation shift at room temperature and insensitivity to the magnetic drift. However, it cannot be laser-cooled directly in the absence of 167nm laser to date. This problem can be solved by sympathetic cooling. In this work, a linear Paul trap is used to trap both 40Ca＋ and 27A1＋ ions simultaneously, and a single Dopplercooled 40Ca＋ ion is employed to sympathetically cool a single 27A1＋ ion. Thus a ＇bright-dark＇ two-ion crystal has been successfully synthesized. The temperature of the crystal has been estimated to be about 7mK by measuring the ratio of carrier and sideband spectral intensities. Finally, the dark ion is proved to be an 27Al＋ ion by precise measuring of the ion crystal＇s secular motion frequency, which means that it is a great step for our 2Z Al＋ quantum logic clock.
基金The project supported by National Natural Science Foundation of China under Grant Nos 19904013 and 1904014
文摘The effect of double frequency oftrap fieldφ=U-V1 cosΩt-V2 cos 2Ωt in a Paul trap can be described exactly by using a function series expansion to solve the corresponding Mathieu equation.The stability regions of a trapped ion are plotted and some meaningful physical results are shown.
基金The project supported by National Natural Science Foundation of China under Grant Nos. 10575034 and 10275023, and the Laboratory of Magnetic Resonance and Atomic and Molccular Physics of China under Grant No. T152504
文摘We have studied the quantum and classical motions of a single Paul trapped ion interacting with a timeperiodic laser field. By using the test-function method, we construct n exact solutions of quantum dynamics that describe the generalized squeezed coherent states with the expectation orbits being the corresponding classical ones. The spacetime evolutions of the exact probability densities show some wavepacket trains. It is demonstrated analytically that by adjusting the laser intensity and frequency, we can control the center motions of the wavepacket trains. We also discuss the other physical properties such as the expectation value of energy, the widths and heights of the wavepackets, and the resonance loss of stability.
基金Supported by the National Basic Research Program of China under Grant No 2010CB832803the National Natural Science Foundation of China under Grant Nos 11004222 and 91121016the Chinese Academy of Sciences
文摘The 7Li＋ ion is one of the most important candidates for verifying QED theory and obtaining the precise value of the fine-structure constant ~. However, direct laser cooling of trapped Li＋ ions will lead to strong background fluorescence which will influence the spectrum detection. The sympathetic cooling technique is a good choice to solve the problem. In this work, we report sympathetic cooling of 7 Li＋ ions to few mK using 40Ca＋ ions in a linear Paul trap. A mixed ion crystal of 40Ca＋ ions and 7Li＋ ions are obtained. We also analyze the motion frequency spectra of pure 40 Ca＋ ions and mixed ions.
