Bulletin of the American Physical Society
52nd Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 66, Number 6
Monday–Friday, May 31–June 4 2021; Virtual; Time Zone: Central Daylight Time, USA
Session K04: Atom-Atom and Atom-Molecule CollisionsLive
|
Hide Abstracts |
Chair: Gil Alexandrowicz, Swansea Univ. |
Wednesday, June 2, 2021 10:30AM - 10:42AM Live |
K04.00001: Three-body universality in ultracold p-wave resonant mixtures Paul Mestrom, Victor Colussi, Thomas Secker, Jinglun Li, Servaas Kokkelmans We study three-body collisions within ultracold mixtures with resonant interspecies p-wave interactions. Our results for the three-body effective interaction strength and decay rate are crucial towards understanding the stability and lifetime of these dilute quantum fluids. On resonance, we find that a class of universal scattering pathways emerges, regardless of the details of the short-range interactions. This gives rise quite generally to a remarkable regime where three-body effective interactions dominate over both inelastic decay and two-body effective interactions. Additionally, we find a series of mass-ratio dependent trimer resonances further from resonance. |
Wednesday, June 2, 2021 10:42AM - 10:54AM Live |
K04.00002: Precision measurement of the Rb-H2 cross-section for the cold atom vacuum standard Pinrui Shen, Riley A Stewart, Perrin Waldock, Kirk W Madison, James Booth We have created a self-defining ultra-high vacuum (UHV) standard based on measuring the loss rate of Rb atoms from a magnetic trap due to collisions with background particles of density n, Γ=n <σv> [New J. Phys. 21 102001 (2019), Metrologia 57 025015 (2020), Metrologia 58 022101 (2021)]. The loss rate coefficient characterizing the collision, <σv>, varies with trap depth, U, and follows a universal law governing quantum diffractive collisions between particles. The value of the loss rate coefficient at zero trap depth can be determined from a fit to the universal function and the precision is dictated by the range of trap depths accessible experimentally. As H2 is the predominant background constituent in the UHV, we have determined the value of the loss rate coefficient for Rb-H2 collisions with an uncertainty of 3% by trapping Rb atoms in the |F = 1, mF = -1> ground hyperfine state. Here, we have doubled the achievable trap depths by preparing the Rb atoms in the |F = 2, mF = 2> hyperfine ground state, which has reduced the uncertainty of the measured loss rate coefficient for Rb-H2 collisions down to the 1% level. This method can be generalized to measure the loss rate coefficients for Rb with other gases to further improve the precision of the cold atom vacuum standard. |
Wednesday, June 2, 2021 10:54AM - 11:06AM Live |
K04.00003: Bootstrapping quantum universality: cross-species calibration of a cold atom pressure sensor Erik B Frieling The atomic sensor is poised to become the first primary UHV pressure standard. The sensor ensemble loss rate is the density of background particles times the loss rate coefficient<σlossv>. Until recently, it was thought that <σlossv>could only be determined from knowledge of the interatomic potentials or from calibration with a known pressure. However, its universal dependence on trap depth allows an experimental determination of the characteristic ”quantum diffractive energy” (Ud) and thus <σlossv>for any background species. This self-calibrating feature opens up the possibility of measuring gases for which the calculation and calibration techniques are not feasible. |
Wednesday, June 2, 2021 11:06AM - 11:18AM Live |
K04.00004: On the formation of molecules through direct three-body recombination: the effect of long-range interactions Marjan Mirahmadi, Jesús Pérez-Ríos We present a study on the role of the long-range tail of pairwise interactions in neutral-neutral-neutral and ion-neutral-neutral direct three-body recombination processes based on a classical trajectory method in hyperspherical coordinates [J. Chem. Phys. 140, 044307 (2014)]. In particular, we focus on the formation of van der Waals molecules X-RG (where RG is a rare gas atom) via X+ RG + RG→X-RG + RG collisions at temperatures relevant for buffer gas cells [J. Chem. Phys. 154, 034305 (2021)], and the formation of molecular ions at low temperatures. As a result, we show that almost any X-RG molecule should appear in a buffer gas cell under appropriate conditions. Furthermore, we investigate the previously derived threshold laws for ion-neutral-neutral systems [J. Chem. Phys. 143, 041105 (2015)] via a systematic method in hyperspherical coordinates. |
Wednesday, June 2, 2021 11:18AM - 11:30AM Live |
K04.00005: Multichannel nature of three-body recombination for ultracold 39K Jinglun Li, Thomas Secker, Paul Mestrom, Servaas Kokkelmans We develop a full multichannel spin model in momentum space to investigate three-body recombination of identical alkali-metal atoms colliding in a magnetic field. The model combines the exact three-atom spin structure and realistic pairwise atom-atom interactions. By neglecting the interaction between two particles when the spectating particle is not in its initial spin state we arrive at an approximate model. With this approximate model, we achieve an excellent agreement with the recent precise measurement of the ground Efimov resonance position in potassium-39 close to 33.58 G [R. Chapurin et al., Phys. Rev. Lett. 123, 233402 (2019)]. We analyze the limitations of our approximation by comparing it to the numerical results for the full system and find that it breaks down for Feshbach resonances at larger magnetic fields in the same spin channel. There the relevant three-body closed channel thresholds are much closer to the open channel threshold, which enhances the corresponding multichannel couplings. Therefore the neglected components of the interaction should be included for those Feshbach resonances. Our model also explains three-body recombination rates observed in the weak interaction regime. |
Wednesday, June 2, 2021 11:30AM - 11:42AM Live |
K04.00006: A van der Waals Characterization of the 4He3 System Daniel M Odell, Lucas Platter, Arnoldas Deltuva The 4He3 system is a playground for universal physics due to the large scattering in the two-body system. The strong -1/r6 van der Waals tail, in particular, uniquely contributes to the features that are worthy of study. As such, I will discuss our efforts the characterize the degree to which the 4He}-4He interaction can be described by a sum of a contact-like interaction and a vdW tail and to understand whether the vdW interaction can be used as the leading order in an effective field theory description of certain classes of atoms. Such a quantification could enhance the understanding and applicability of vdW universality. I will present results in the two- and three-body sectors demonstrating the efficacy of the vdW effective theory and the possible promise of the theory's ability to quantify corrections to predictions from vdW universality. |
Wednesday, June 2, 2021 11:42AM - 11:54AM Live |
K04.00007: AlF-He cold collision: Rotational quenching and buffer gas cooling efficiency Mallikarjun Karra, Miruna Cretu, Jesús Pérez-Ríos We present a study of the state-to-state scattering cross-sections pertaining to the AlF-He collisions at cold temperatures (E > 1mK) with AlF being in its vibrational ground state. The relevant cross sections are obtained via a coupled channel approach fed with a novel two-dimensional ab initio potential energy surface. The coupled channel results for the elastic cross sections are contrasted with a single-channel calculation as well as a semi-classical approach that is commonly used to estimate a molecule's cooling and diffusion properties in a buffer gas. Consequently, we evaluate the role of shape resonances at energies relevant to buffer gas cooling experiments. In addition, relaxation rates for the relevant rotational states of AlF are also calculated. |
Wednesday, June 2, 2021 11:54AM - 12:06PM Live |
K04.00008: Transfer matrix theory of molecular spin-echo experiments of dynamic surfaces Joshua T Cantin, Gil Alexandrowicz Molecular spin-echo experiments are able to quantitatively determine both the amplitudes and phases of the quantum state-to-state transition amplitudes in molecule-surface scattering experiments [1]. The available theoretical frameworks describing these molecular spin-echo experiments can only describe scattering by static surfaces, however. Here, we exploit the short-range nature of the time-dependent molecule-surface interactions to expand the transfer matrix theory of molecular spin-echo experiments to incorporate the effects of surface dynamics. Under the Born approximation and assuming pairwise interactions between the molecule and the adsorbates, we demonstrate that the molecular spin echo signal is a function of the familiar time-dependent pair correlation function of the surface and of a molecular form factor. We then numerically implement this formalism, demonstrate that it reproduces the expected results for ${}^3$He spin-echo experiments and illustrate how the \emph{o}H$_{2}$ spin echo signal is impacted by surface dynamics. This work provides a fully quantum theoretical framework necessary to interpret molecular spin echo experiments studying dynamic surfaces. |
Wednesday, June 2, 2021 12:06PM - 12:18PM Live |
K04.00009: Temperature relaxation in strongly-coupled binary ionic mixtures Robert T Sprenkle, Luciano G Silvestri, Michael S Murillo, Scott D Bergeson New facilities such as the National Ignition Facility and the Linac Coherent Light Source have pushed the frontiers of high energy-density matter. These facilities offer unprecedented opportunities for exploring extreme states of matter, ranging from cryogenic solid-state systems to hot, dense plasmas, with applications to inertial-confinement fusion and astrophysics. However, significant gaps in our understanding of material properties in these rapidly evolving systems still persist. In particular, non-equilibrium transport properties of strongly-coupled Coulomb systems remain an open question. Here, we study ion-ion temperature relaxation in a binary mixture, exploiting a recently-developed dual-species ultracold neutral plasma. We compare measured relaxation rates with atomistic simulations and a range of popular theories. Our work validates the assumptions and capabilities of the simulations and invalidates theoretical models in this regime. This work illustrates an approach for precision determinations of detailed material properties in Coulomb mixtures across a wide range of conditions. |
Wednesday, June 2, 2021 12:18PM - 12:30PM Live |
K04.00010: A simple model to describe electric field shielding of two-body ultracold molecular collisions Lucas Lassablière, Goulven Quéméner Recent experiments have shown that ultracold dipolar molecules, whether they are reactive or not, are prone to two-body molecular losses. This is a main drawback to create long-lived quantum degenerate gases. To overcome this, one can shield the molecules against collisions for which many set-ups have been proposed. |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700