19 research outputs found
Magnetic and electric dipole moments of the state in ThO
The metastable state in the thorium monoxide (ThO)
molecule is highly sensitive to the presence of a CP-violating permanent
electric dipole moment of the electron (eEDM). The magnetic dipole moment
and the molecule-fixed electric dipole moment of this state are
measured in preparation for a search for the eEDM. The small magnetic moment
displays the predicted cancellation of
spin and orbital contributions in a paramagnetic molecular
state, providing a significant advantage for the suppression of magnetic field
noise and related systematic effects in the eEDM search. In addition, the
induced electric dipole moment is shown to be fully saturated in very modest
electric fields ( 10 V/cm). This feature is favorable for the suppression of
many other potential systematic errors in the ThO eEDM search experiment.Comment: 4 pages, 3 figure
Search for the electric dipole moment of the electron with thorium monoxide
The electric dipole moment of the electron (eEDM) is a signature of
CP-violating physics beyond the Standard Model. We describe an ongoing
experiment to measure or set improved limits to the eEDM, using a cold beam of
thorium monoxide (ThO) molecules. The metastable state in ThO
has important advantages for such an experiment. We argue that the statistical
uncertainty of an eEDM measurement could be improved by as much as 3 orders of
magnitude compared to the current experimental limit, in a first-generation
apparatus using a cold ThO beam. We describe our measurements of the state
lifetime and the production of ThO molecules in a beam, which provide crucial
data for the eEDM sensitivity estimate. ThO also has ideal properties for the
rejection of a number of known systematic errors; these properties and their
implications are described.Comment: v2: Equation (11) correcte
Magnetic and electric dipole moments of the H^3 Δ_1 state in ThO
The metastable H^3 Δ_1 state in the thorium monoxide (ThO) molecule is highly sensitive to the presence of a CP
-violating permanent electric dipole moment of the electron (eEDM) [E. R. Meyer and J. L. Bohn, Phys. Rev. A 78, 010502 (2008)]. The magnetic dipole moment μ_H and the molecule-fixed electric dipole moment D_H of this state are measured in preparation for a search for the eEDM. The small magnetic moment μH=8.5(5)×10^(−3)μ_B displays the predicted cancellation of spin and orbital contributions in a ^3Δ_1 paramagnetic molecular state, providing a significant advantage for the suppression of magnetic field noise and related systematic effects in the eEDM search. In addition, the induced electric dipole moment is shown to be fully saturated in very modest electric fields (<10 V/cm). This feature is favorable for the suppression of many other potential systematic errors in the ThO eEDM search experiment
Shot-noise-limited spin measurements in a pulsed molecular beam
Heavy diatomic molecules have been identified as good candidates for use in
electron electric dipole moment (eEDM) searches. Suitable molecular species can
be produced in pulsed beams, but with a total flux and/or temporal evolution
that varies significantly from pulse to pulse. These variations can degrade the
experimental sensitivity to changes in spin precession phase of an electri-
cally polarized state, which is the observable of interest for an eEDM
measurement. We present two methods for measurement of the phase that provide
immunity to beam temporal variations, and make it possible to reach
shot-noise-limited sensitivity. Each method employs rapid projection of the
spin state onto both components of an orthonormal basis. We demonstrate both
methods using the eEDM-sensitive H state of thorium monoxide (ThO), and use one
of them to measure the magnetic moment of this state with increased accuracy
relative to previous determinations.Comment: 12 pages, 6 figure
Laser cooling of a diatomic molecule
It has been roughly three decades since laser cooling techniques produced
ultracold atoms, leading to rapid advances in a vast array of fields.
Unfortunately laser cooling has not yet been extended to molecules because of
their complex internal structure. However, this complexity makes molecules
potentially useful for many applications. For example, heteronuclear molecules
possess permanent electric dipole moments which lead to long-range, tunable,
anisotropic dipole-dipole interactions. The combination of the dipole-dipole
interaction and the precise control over molecular degrees of freedom possible
at ultracold temperatures make ultracold molecules attractive candidates for
use in quantum simulation of condensed matter systems and quantum computation.
Also ultracold molecules may provide unique opportunities for studying chemical
dynamics and for tests of fundamental symmetries. Here we experimentally
demonstrate laser cooling of the molecule strontium monofluoride (SrF). Using
an optical cycling scheme requiring only three lasers, we have observed both
Sisyphus and Doppler cooling forces which have substantially reduced the
transverse temperature of a SrF molecular beam. Currently the only technique
for producing ultracold molecules is by binding together ultracold alkali atoms
through Feshbach resonance or photoassociation. By contrast, different proposed
applications for ultracold molecules require a variety of molecular
energy-level structures. Our method provides a new route to ultracold
temperatures for molecules. In particular it bridges the gap between ultracold
temperatures and the ~1 K temperatures attainable with directly cooled
molecules (e.g. cryogenic buffer gas cooling or decelerated supersonic beams).
Ultimately our technique should enable the production of large samples of
molecules at ultracold temperatures for species that are chemically distinct
from bialkalis.Comment: 10 pages, 7 figure
Magnetic and electric dipole moments of the H^3 Δ_1 state in ThO
The metastable H^3 Δ_1 state in the thorium monoxide (ThO) molecule is highly sensitive to the presence of a CP
-violating permanent electric dipole moment of the electron (eEDM) [E. R. Meyer and J. L. Bohn, Phys. Rev. A 78, 010502 (2008)]. The magnetic dipole moment μ_H and the molecule-fixed electric dipole moment D_H of this state are measured in preparation for a search for the eEDM. The small magnetic moment μH=8.5(5)×10^(−3)μ_B displays the predicted cancellation of spin and orbital contributions in a ^3Δ_1 paramagnetic molecular state, providing a significant advantage for the suppression of magnetic field noise and related systematic effects in the eEDM search. In addition, the induced electric dipole moment is shown to be fully saturated in very modest electric fields (<10 V/cm). This feature is favorable for the suppression of many other potential systematic errors in the ThO eEDM search experiment
Shot-noise-limited spin measurements in a pulsed molecular beam
Heavy diatomic molecules have been identified as good candidates for use in electron electric dipole moment (eEDM) searches. Suitable molecular species can be produced in pulsed beams, but with a total flux and/or temporal evolution that varies significantly from pulse to pulse. These variations can degrade the experimental sensitivity to changes in the spin precession phase of an electrically polarized state, which is the observable of interest for an eEDM measurement. We present two methods for measurement of the phase that provide immunity to beam temporal variations, and make it possible to reach shot-noise-limited sensitivity. Each method employs rapid projection of the spin state onto both components of an orthonormal basis. We demonstrate both methods using the eEDM-sensitive H^3Δ^1 state of thorium monoxide, and use one of them to measure the magnetic moment of this state with increased accuracy relative to previous determinations
Searching for New Physics Through AMO Precision Measurements
We briefly review recent experiments in atomic, molecular, and optical
physics using precision measurements to search for physics beyond the Standard
Model. We consider three main categories of experiments: searches for changes
in fundamental constants, measurements of the anomalous magnetic moment of the
electron, and searches for an electric dipole moment of the electron.Comment: Prepared for Comments on AMO Physics at Physica Script
Methods, analysis, and the treatment of systematic errors for the electron electric dipole moment search in thorium monoxide
We recently set a new limit on the electric dipole moment of the electron (eEDM) (J Baron et al and ACME collaboration 2014 Science 343 269–272), which represented an order-of-magnitude improvement on the previous limit and placed more stringent constraints on many charge-parity-violating extensions to the standard model. In this paper we discuss the measurement in detail. The experimental method and associated apparatus are described, together with the techniques used to isolate the eEDM signal. In particular, we detail the way experimental switches were used to suppress effects that can mimic the signal of interest. The methods used to search for systematic errors, and models explaining observed systematic errors, are also described. We briefly discuss possible improvements to the experiment