关键词: 超冷Rydberg分子/
双色光缔合/
绝热势能曲线
English Abstract
Two-color photoassociation spectra of ultra-cold Cs (60D5/2)2 Rydberg molecule
Bai Jing-Xu1,Han Xiao-Xuan1,
Bai Su-Ying1,
Jiao Yue-Chun1,2,
Zhao Jian-Ming1,2,
Jia Suo-Tang1,2
1. State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Shanxi University, Taiyuan 030006, China;
2. Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China
Fund Project:Project supported by the National Key R&D Program of China (Grant No. 2017YFA0304203), the National Nature Science Foundation of China (Grant Nos. 61475090, 61675123, 61775124, 11804202), the Key Program of the National Natural Science Foundation of China (Grant No. 11434007, 61835007), the Changjiang Scholars and Innovative Research Team in University of Ministry of Education of China (Grant No. IRT_17R70), and the "1331 Project" of Shanxi Province, China.Received Date:21 September 2018
Accepted Date:21 October 2018
Published Online:05 December 2018
Abstract:The long-range multipole interactions between ultra-cold Rydberg atoms form adiabatic potentials, one of which shows a binding potential that can be used to bind Rydberg-Rydberg molecules. Rydberg-atom molecule, known as macrodimer due to its larger size (~μm), has the properties of the abundant vibrational energy levels and large electric dipole moment and so on. Compared with Rydberg atom, the Rydberg molecule, including Rydberg-ground molecule and Rydberg-Rydberg molecule, is susceptible to manipulate by an external field and possesses potential applications in the weak-signal detection, the quantum gas correlation measurement and the vacuum fluctuation and so on.
In this paper, we investigate a (60D5/2)2 Rydberg macrodimer theoretically and experimentally. In the calculation, we take into account the multipole interaction of a Rydberg-atom pair, including dipole-dipole, dipole-quadrupole, dipole-octupole and quadrupole-quadrupole interaction and so on. The adiabatic potential of 60D5/2 Rydberg-atom pair is obtained by diagonalizing the interaction Hamiltonian on a grid of internuclear separations, R. The potential depth and binding length of the Rydberg molecular potential well are obtained. In experiment, we prepare the ultra-cold Cs (60D5/2)2 Rydberg molecules by a two-color photoassociation method in a cesium ultracold atom trap. The first-color (pulse-A) resonantly excites a seed Rydberg atom A, and the second color (pulse-B) is detuned and resonantly excites the second Rydberg atom B near to the atom A. Both pulse-A and pulse-B are two-photon excitations (852 nm + 510 nm), between which their 852-nm lasers have the same frequency, whereas the 510-nm laser frequency of the pulse-A is set to be resonant with the atomic transition and the frequency of the pulse-B is detuned by using a double-passed acousto-optic modulator. When the pulse-B is detuned to the molecular binding energy, atom-A and-B are bonded, forming an ultra-cold Cs (60D5/2)2 Rydberg molecule. The two-color photoassociation spectra of Rydberg-Rydberg molecules are detected by the field ionization of Rydberg atoms and molecules with a ramped electric field. Molecular spectra are compared with calculated adiabatic molecular potentials, which yields the binding energy and equilibrium internuclear distance. The two-color photoassociation method used in this work has a doubly resonant character that results in the enhanced excitation rate.
Keywords: ultra-cold Rydberg-Rydberg molecule/
two-color photoassociation/
oindent adiabatic potential
