An Improved Measurement of Cesium Ground State Tensor Polarizability
Open Access
- Author:
- Zhang, Teng
- Graduate Program:
- Physics
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- June 17, 2021
- Committee Members:
- Nitin Samarth, Program Head/Chair
Mikael Rechtsman, Major Field Member
David Weiss, Chair & Dissertation Advisor
Joan Redwing, Outside Unit & Field Member
Martin Bojowald, Major Field Member - Keywords:
- Precision Measurement
Cold atoms - Abstract:
- Precision measurements with cold atoms can test fundamental symmetries in the standard model of particle physics, in a way that is complementary to experiments carried out with large scale colliders. For example, searches for the electric dipole moments (EDM) of elementary particles can probe time-reversal symmetry violating interactions. Measurements of atomic parity violation can test parity violation in the low-energy electroweak sector. In order to extract the underlying elecroweak physics from atomic parity violation measurements, precise atomic calculations are needed. The ground state tensor polarizability (GSTP) of Cs is sensitive to a range of hyperfine interactions between nuclear moments and electrons, which are among the most challenging parts of atomic parity violation theory. A precise measurement of the GSTP provides a rare opportunity to test the calculations that are used in atomic parity violation theory. This dissertation reports on our GSTP measurement and our future Cs atomic EDM measurement. For both measurements, we use laser-cooled Cs atoms trapped in two parallel optical lattices. The lattices thread three coated electric field plates which are surrounded by a four-layer mu-metal magnetic shield. A series of microwave pulses transfers the atoms into the desired spin state for each measurement. The GSTP measurement looks for a quadratic energy shift in the electric field, while the EDM measurement is a search for a linear energy shift. We separately collect signals from spatially resolved atom groups in order to cancel out residual magnetic gradients and diagnose potential systematic errors. We have taken the GSTP data and studied some of the systematic effects to a level of better than 10^-3. There final data analysis for a final GSTP measurement result is ongoing. We have also developed an alternative measurement scheme for our Cs EDM experiment. This scheme uses spin precession starting from the mF = 0 state. We compared this scheme with the orginal measurement scheme in sensitivity and feasibility given our current apparatus status. We have also developed a measurement scheme for the Stark shift of the clock transition, which can potentially achieve a precision of 10^-3.