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1. A Synchronous Spin-Exchange Optically Pumped NMR-Gyroscope

   https://doi.org/10.3390/app10207099  

   Sorensen, Susan S. ; Thrasher, Daniel A. ; Walker, Thad G. ( October 2020 , Applied Sciences)

   Inertial navigation systems generally consist of timing, acceleration, and orientation measurement units. Although much progress has been made towards developing primary timing sources such as atomic clocks, acceleration and orientation measurement units often require calibration. Nuclear Magnetic Resonance (NMR) gyroscopes, which rely on continuous measurement of the simultaneous Larmor precession of two co-located polarized noble gases, can be configured to have scale factors that depend to first order only on fundamental constants. The noble gases are polarized by spin-exchange collisions with co-located optically pumped alkali-metal atoms. The alkali-metal atoms are also used to detect the phase of precession of themore »polarized noble gas nuclei. Here we present a version of an NMR gyroscope designed to suppress systematic errors from the alkali-metal atoms. We demonstrate rotation rate angle random walk (ARW) sensitivity of 16μHz/Hz and bias instability of ∼800 nHz.« less
2. Final results for the neutron β -asymmetry parameter A ₀ from the UCNA experiment

   https://doi.org/10.1051/epjconf/201921904004  

   Plaster, B. ; Adamek, E. ; Allgeier, B. ; Anaya, J. ; Back, H.O. ; Bagdasarova, Y. ; Berguno, D.B. ; Blatnik, M. ; Boissevain, J.G. ; Bowles, T.J. ; et al ( January 2019 , EPJ Web of Conferences)

   The UCNA experiment was designed to measure the neutron β-asymmetry parameter A 0 using polarized ultracold neutrons (UCN). UCN produced via downscattering in solid deuterium were polarized via transport through a 7 T magnetic field, and then directed to a 1 T solenoidal electron spectrometer, where the decay electrons were detected in electron detector packages located on the two ends of the spectrometer. A value for A 0 was then extracted from the asymmetry in the numbers of counts in the two detector packages. We summarize all of the results from the UCNA experiment, obtained during run periods in 2007, 2008–2009, 2010,more »and 2011–2013, which ultimately culminated in a 0.67% precision result for A 0 .« less
3. Measurement of the neutron lifetime using a magneto-gravitational trap and in situ detection

   https://doi.org/10.1126  

   Pattie, R.W. ; Callahan, N.B. ; Cude-Woods, C. ; Adamek, E.R. ; Broussard, L.J. ; Clayton, S.M. ; Currie, S.A. ; Dees, E.B. ; Ding, X. ; Engel, E.M. ; et al ( May 2018 , Science)

   The precise value of the mean neutron lifetime, tau_n, plays an important role in nuclear and particle physics and cosmology. It is used to predict the ratio of protons to helium atoms in the primordial universe and to search for physics beyond the Standard Model of particle physics. We eliminated loss mechanisms present in previous trap experiments by levitating polarized ultracold neutrons above the surface of an asymmetric storage trap using a repulsive magnetic field gradient so that the stored neutrons do not interact with material trap walls. As a result of this approach and the use of an inmore »situ neutron detector, the lifetime reported here [877.7 +/- 0.7 (stat) +0.4/-0.2 (sys) seconds] does not require corrections larger than the quoted uncertainties.« less
4. Improved limit on the electric dipole moment of the electron

   https://doi.org/10.1038/s41586-018-0599-8  

   V. Andreev, D. G. ( October 2018 , Nature)

   The standard model of particle physics accurately describes all particle physics measurements made so far in the laboratory. However, it is unable to answer many questions that arise from cosmological observations, such as the nature of dark matter and why matter dominates over antimatter throughout the Universe. Theories that contain particles and interactions beyond the standard model, such as models that incorporate supersymmetry, may explain these phenomena. Such particles appear in the vacuum and interact with common particles to modify their properties. For example, the existence of very massive particles whose interactions violate time-reversal symmetry, which could explain the cosmologicalmore »matter–antimatter asymmetry, can give rise to an electric dipole moment along the spin axis of the electron. No electric dipole moments of fundamental particles have been observed. However, dipole moments only slightly smaller than the current experimental bounds have been predicted to arise from particles more massive than any known to exist. Here we present an improved experimental limit on the electric dipole moment of the electron, obtained by measuring the electron spin precession in a superposition of quantum states of electrons subjected to a huge intramolecular electric field. The sensitivity of our measurement is more than one order of magnitude better than any previous measurement. This result implies that a broad class of conjectured particles, if they exist and time-reversal symmetry is maximally violated, have masses that greatly exceed what can be measured directly at the Large Hadron Collider.« less
5. Prospects for assembling ultracold radioactive molecules from laser-cooled atoms

   https://doi.org/10.1088/1367-2630/ac50ea  

   Kłos, Jacek ; Li, Hui ; Tiesinga, Eite ; Kotochigova, Svetlana ( February 2022 , New Journal of Physics)

   Abstract Molecules with unstable isotopes often contain heavy and deformed nuclei and thus possess a high sensitivity to parity-violating effects, such as the Schiff moments. Currently the best limits on Schiff moments are set with diamagnetic atoms. Polar molecules with quantum-enhanced sensing capabilities, however, can offer better sensitivity. In this work, we consider the prototypical 223 Fr 107 Ag molecule, as the octupole deformation of the unstable 223 Fr francium nucleus amplifies the nuclear Schiff moment of the molecule by two orders of magnitude relative to that of spherical nuclei and as the silver atom has a large electron affinity.more »To develop a competitive experimental platform based on molecular quantum systems, 223 Fr atoms and 107 Ag atoms have to be brought together at ultracold temperatures. That is, we explore the prospects of forming 223 Fr 107 Ag from laser-cooled Fr and Ag atoms. We have performed fully relativistic electronic-structure calculations of ground and excited states of FrAg that account for the strong spin-dependent relativistic effects of Fr and the strong ionic bond to Ag. In addition, we predict the nearest-neighbor densities of magnetic-field Feshbach resonances in ultracold 223 Fr + 107 Ag collisions with coupled-channel calculations. These resonances can be used for magneto-association into ultracold, weakly-bound FrAg. We also determine the conditions for creating 223 Fr 107 Ag molecules in their absolute ground state from these weakly-bound dimers via stimulated Raman adiabatic passage using our calculations of the relativistic transition electric dipole moments.« less