Jul 17 – 22, 2022
Royal Conservatory of Music, Toronto
America/Toronto timezone

An Experiment to Measure the Electron's Electric Dipole Moment Using an Ultracold Beam of YbF Molecules

Jul 19, 2022, 5:00 PM
1h 30m
Hart House (Hart House)

Hart House

Hart House

7 Hart House Cir, Toronto, ON M5S 3H3
Poster presentation Precision measurement and tests of fundamental physics Poster session


The standard model predicts that the electron’s electric dipole moment (eEDM, $d_e$) is too small to measure with current technology [1]. Theories that extend the standard model, however, predict much larger values, often exceeding $10^{-29}~e~\text{cm}$. With the current experimental upper limit set at $|d_e| < 1.1 \times 10^{-29}~e~\text{cm}$, [2] we can expect that improved measurements will either discover new physics or rule out most of the remaining parameter space for popular theories beyond the standard model. Measurements of $d_e$ are made by measuring the precession of the electron spin induced by an applied electric field. The precession angle is enhanced when the electron is bound to a heavy polar molecule. The precision can be further improved by increasing the spin precession time and the total number of molecules detected. To this end, we have produced an intense beam of laser-cooled YbF molecules [3] and built an experiment to measure $d_e$ using this beam [4]. The laser cooling lowers the temperature below $100~\mathrm{\mu K}$ and increases the beam brightness by at least a factor of 300, leading to a projected statistical sensitivity better than $10^{-30}~e~\text{cm}$. Realising such high precision requires a spin precession region with exceptionally low magnetic noise. Our apparatus features ceramic electric field plates inside a glass vacuum chamber, minimising magnetic Johnson noise, a four-layer magnetic shield with a shielding factor exceeding $10^6$, and an array of atomic magnetometers. The magnetic noise in the apparatus is below $50~\mathrm{fT} /\sqrt{\mathrm{Hz}}$ at 1 Hz. The poster will present our progress in laser cooling YbF molecules and our characterisation and optimisation of the eEDM apparatus.

[1] M. Pospelov and A. Ritz., CKM benchmarks for electron electric dipole moment experiments., Phys. Rev. D, 89, 056006, (2014).
[2] V. Andreev et al., Improved limit on the electric dipole moment of the electron., Nature, 562, 355–360, (2018).
[3] X. Alauze et al., An ultracold molecular beam for testing fundamental physics, Quantum Sci. Technol., 6, 044005, (2021).
[4] N. J. Fitch, J. Lim, E. A. Hinds, B. E. Sauer, and M. R. Tarbutt., Methods for measuring the electron’s electric dipole moment using ultracold YbF molecules, Quantum Sci. Technol., 6, 014006, (2021).

Presenter name Freddie Collings
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Primary authors

Mr Freddie Collings (Imperial College London) Dr Rhys Jenkins (Imperial College London) Dr Xavier Y Alauze (Imperial College London) Mr Gen Li (Imperial College London) Mr Simon Swarbrick (Imperial College London) Mr Christopher Ho Dr Noah J Fitch (Imperial College London) Prof. Ben E Sauer (Imperial College London) Prof. Michael R Tarbutt (Imperial College London)

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