Date: Tuesday 30 July
Time: 10:00am – 11:00pm AWST, 12:00am -1:00pm AEST
Location: Details have been emailed to all EQUS members.
Speaker: Chuankun Zhang
Title: Dawn of a nuclear clock: frequency ratio of the 229mTh isomeric transition and the 87Sr atomic clock.
Bio: Chuankun Zhang is a graduate student working in the group of Prof. Jun Ye at JILA, NIST and University of Colorado, Boulder. His research focuses on the development of the next generation optical clock based on an accessible nuclear clock transition in 229Th. He and colleagues in the Ye group worked on multiple fronts to build the first nuclear clock, involving the development and stabilization of a vacuum-ultraviolet frequency comb, the fabrication and characterization of 229ThF4 thin film targets for future integrated nuclear clocks, and have demonstrated the first quantum state-resolved nuclear laser spectroscopy with the absolute frequency referenced to an atomic clock. During his undergrad study at Tsinghua University, he built lasers and electronics in the group of Prof. Meng Khoon Tey. He was an undergraduate visiting student at EPFL, where he worked on mid-IR comb generation with Prof. Tobias Kippenberg.
Abstract: Optical atomic clocks use electronic energy levels to precisely keep track of time. A clock based on nuclear energy levels promises a next-generation platform for precision metrology and fundamental physics studies. Here, we report quantum state-resolved spectroscopy of the 229mTh isomer to determine the underlying nuclear structure and establish a direct frequency connection with existing atomic clocks using a frequency comb in the vacuum ultraviolet. We also precisely measure the nuclear quadrupole splittings and extract intrinsic nuclear properties. These results mark the start of nuclear-based solid-state optical clock and demonstrate the first comparison of nuclear and atomic clocks for fundamental physics studies. This work represents a confluence of precision metrology, ultrafast strong field physics, nuclear physics, and fundamental physics.
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