Populating 229mTh via two-photon electronic bridge mechanism

• 作者: Neng-Qiang Cai Guo-Qiang Zhang Chang-Bo Fu Yu-Gang Ma
• 来源期刊: 核技术（英文版）
• 年，卷（期）: 2021,（6）
• 所属期刊栏目: NUCLEAR PHYSICS AND INTERDISCIPLINARY RESEARCH
• 页码范围: 93-101
• 页数: 9页
• 语种: 英文

摘要

The isomer 229mTh is the most promising can-didate for clocks based on the nuclear transition because it has the lowest excitation energy of only 8.10±0.17 eV.Various experiments and theories have focused on methods of triggering the transition between the ground state and isomeric state,among which the electronic bridge(EB)is one of the most efficient.In this paper,we propose a new electronic bridge mechanism via two-photon excitation based on quantum optics for a two-level nuclear quantum system.The long-lived 7s1/2 electronic shell state of 229mTh3+,with a lifetime of approximately 0.6 s,is chosen as the initial state and the atomic shells(7s-10s)could be achieved as virtual states in a two-photon process.When the virtual states return to the initial state 7s1/2,there is a chance of triggering the nucleus 229Th3+to its isomeric state 229mTh3+via EB.Two lasers at moderate intensity((1010-1014)W/m2),with photon energies near the optical range,are expected to populate the isomer at a saturated rate of approximately 109s-1,which is much higher than that due to other mechanisms.We believe that this two-photon EB scheme can help in the development of nuclear clocks and deserves verification via a series of experiments with ordinary lasers in laboratories.