Bulletin of the American Physical Society
47th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 61, Number 8
Monday–Friday, May 23–27, 2016; Providence, Rhode Island
Session U6: Photoassociation and Collisons, Optical Feshbach Resonances |
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Chair: Sebastian Will, Massachusetts Institute of Techology Room: 552AB |
Friday, May 27, 2016 10:30AM - 10:42AM |
U6.00001: Observation of Resonant Effects in Ultracold Collisions between Heteronuclear Feshbach Molecules Xin Ye, Fudong Wang, Bing Zhu, Mingyang Guo, Bo Lu, Dajun Wang Magnetic field dependent dimer-dimer collisional losses are studied with ultracold $^{23}$Na$^{87}$Rb Feshbach molecules. By ramping the magnetic field across the 347.8 G inter-species Feshbach resonance and removing residual atoms with a magnetic field gradient, $\sim$8000 pure NaRb Feshbach molecules with a temperature below 1 $\mu$K are produced. By holding the pure molecule sample in a crossed optical dipole trap and measuring the time-dependent loss curves under different magnetic fields near the Feshbach resonance, the dimer-dimer loss rates with respect to the atomic scattering length a are mapped out. We observe a resonant feature at around $a = 600 a_{0}$ and a rising tail at above $a = 1600 a_{0}$. This behavior resembles previous theoretical works on homonuclear Feshbach molecule, where resonant effects between dimer-dimer collisions tied to tetramer bound states were predicted. Our work shows the possibility of exploring four-body physics within a heteronuclear system. [Preview Abstract] |
Friday, May 27, 2016 10:42AM - 10:54AM |
U6.00002: An optically trapped mixture of alkali-metal and metastable helium atoms Adonis Flores, Hari Prasad Mishra, Wim Vassen, Steven Knoop Ultracold collisions between alkali-metal and metastable triplet helium (He*) atoms provide the opportunity to study Feshbach resonances in the presence of a strong loss channel, namely Penning ionization, which strongly depends on the internal spin-states of the atoms. Recently we have realized the first optically trapped alkali-metal-metastable helium mixture. To prepare the ultracold $^{\mathrm{87}}$Rb$+^{\mathrm{4}}$He* mixture in a single beam optical dipole trap (ODT), we apply evaporative cooling in a strong quadrupole magnetic trap (QMT) for both species and subsequent transfer to the ODT via a hybrid trap [1,2]. We will present lifetime measurements of different spin-state mixtures, testing the application of the universal loss model [3] to this interesting multichannel collision system. [1] H. P. Mishra, A. S. Flores, W. Vassen, S. Knoop, Eur. Phys. J. D 69, 52 (2015) [2] A. S. Flores, H. P. Mishra, W. Vassen, S. Knoop, Appl. Phys. B 121, 391 (2015) [3] Z. Idziaszek and P. S. Julienne, Phys. Rev. Lett. 104, 113202 (2010) [Preview Abstract] |
Friday, May 27, 2016 10:54AM - 11:06AM |
U6.00003: Observation of broad p-wave Feshbach resonances in a $^{85}$Rb-$^{87}$Rb mixture Shen Dong, Yue Cui, Chuyang Shen, Bo Gao, Meng Khoon Tey, Li You Many Feshbach resonances are observed in an ultracold mixture of $^{85}$Rb-$^{87}$Rb atoms, including three previously unknown resonances in the lowest ground state channel of $^{85}$Rb$|2, 2\rangle \otimes ^{87}$Rb$|1, 1\rangle$ and three new ones in the higher ground channel $|2, -2\rangle \otimes |1, -1\rangle$ [1]. Of particular interests, we discover a wide and open-channel-dominated p-wave resonance, implicating exciting opportunities for studying a variety of p-wave interaction dominated physics of superfluid boson mixtures, such as three-body recombination decay and formation of p-wave heteronuclear molecules. This study is made possible by the predictive power of the semi-analytic multi-channel quantum defect theory (MQDT) [2]. \\\\ 1. S. B. Papp and C. E. Wieman,Phys. Rev. Lett. \textbf{97}, 180404 (2006).\\ 2. Bo Gao, Phys. Rev. A \textbf{84}, 022706 (2011). [Preview Abstract] |
Friday, May 27, 2016 11:06AM - 11:18AM |
U6.00004: Testing Universality of Efimov Physics in an Ultracold Mixture of Lithium and Cesium Atoms Jacob Johansen, Brian DeSalvo, Cheng Chin We conduct a survey of Li-Cs-Cs Efimov resonances in a $^6$Li-$^{133}$Cs mixture in the magnetic field range of 800 to 950 G. In this region, limiting our study to the two lowest Zeeman levels of lithium and the lowest Zeeman level of cesium, there are five Feshbach resonances which may be probed. The Cs-Cs scattering length at these resonances varies from -3600 a$_0$ to +1000 a$_0$, allowing us to study the impact of the Cs-Cs scattering length on the Efimov resonance positions. In addition, a combination of broad and narrow Feshbach resonances in this magnetic field range allows us to probe the influence of molecular physics on the Efimov effect, particularly the variation of the three-body parameter. [Preview Abstract] |
Friday, May 27, 2016 11:18AM - 11:30AM |
U6.00005: Strong photoassociation in a degenerate fermi gas Timur Rvachov, Alan Jamison, Li Jing, Hyungmok Son, Sepehr Ebadi, Yijun Jiang, Martin Zwierlein, Wolfgang Ketterle Despite many studies there remain open questions about strong photoassociation in ultracold gases. We study the effects of strong photoassociation in ultracold fermions. Photoassociation occurs only at short range and thus can be used as a tool to probe and control the two-body correlation function in an interacting many-body system. We study the effects of strong photoassociation in $^6$Li, the onset of saturation, and its effects on spin polarized and interacting spin-mixtures. [Preview Abstract] |
Friday, May 27, 2016 11:30AM - 11:42AM |
U6.00006: Spin-sensitive photoassociation in Rb-87 BEC with spin and spin-momentum superposition dressed states David Blasing, Su-Ju Wang, Jesús Pérez-Ríos, Chuan-Hsun Li, Sourav Dutta, Chris Greene, Yong Chen We present our experimental studies of spin-sensitive photoassociation in Rb-87 F=1 spinor Bose-Einstein condensate (BEC) with and without the presence of Raman light-induced mf spin coupling. Without the Raman coupling, the photoassociation transition is only allowed between two atoms of bare mf spin states (0,0) or (1,-1). Copropagating or counterpropagating Raman beams couple bare mf spin states, and can create new “dressed” eigenstates of superpositions between either just mf spin or mf spin-momentum states. We report our observations on how either type of coupling and dressed states affect the PA process. [Preview Abstract] |
Friday, May 27, 2016 11:42AM - 11:54AM |
U6.00007: Production of rovibronic ground-state $^{85}$Rb$^{133}$Cs molecules via photoassociation to $\Omega=1$ states Toshihiko Shimasaki, Jin Tae Kim, David DeMille We have extensively investigated short-range photoassociation (PA) to the $(2)^3\Pi_1$, $(2)^1\Pi_1$, and $(3)^3\Sigma^+_1$ states of $^{85}$Rb$^{133}$Cs in the region between 11650 cm$^{-1}$ and 12100 cm$^{-1}$, where strong mixing between triplet and singlet states is expected. In contrast to the previously observed two-photon cascade decay from the $(2)^3 \Pi_0$ states \footnote{T. Shimasaki {\it et al.} Phys. Rev. A, 91, 021401(R)(2015)}, here we observe that the PA excited states can directly decay to the rovibronic ground state $X^1\Sigma^+ (v=0,J=0)$ by a one-photon transition. We have observed rich hyperfine structures of the PA states, which were unresolved in previous cold beam experiments in the same region \footnote{Y. Lee {\it et al.} J. Phys. Chem. A, 112, 7214(2008)}. Based on the analysis of vibrational and rotational branching ratios in the decay process to the $X^1\Sigma^+$ state, we will discuss the molecule production rate in comparison with that for PA to the $(2)^3 \Pi_0$ states. We will also report on a similar study of PA to the $B^1\Pi$ and $(2)^3 \Sigma^+_1$ states of $^{85}$Rb$^{133}$Cs, which also produce the rovibronic ground state $X^1\Sigma^+ (v=0,J=0)$ via direct one-photon decay. [Preview Abstract] |
Friday, May 27, 2016 11:54AM - 12:06PM |
U6.00008: Radio frequency field assisted cold collisions Yijue Ding, Jose D'Incao, Chris Greene The radio frequency (RF) field is a promising but less developed tool to control cold collisions. From the few-body perspective, we study cold atom collisions in an external magnetic field and a single-color RF field. We employ the multi-channel quantum defect theory and the hyperspherical toolkit to solve the two-body and three-body Schrödinger equations. Our results show that RF fields can effectively control the two-body scattering length through Feshbach resonances. Such RF induced Feshbach resonances can be applied to quenching experiments or spinor condensates. Analogous to photo association, RF fields can also associate cold atoms into molecules with a reasonable rate. Moreover, we will discuss the feasibility of using RF fields to control three-body recombination, which may improve the experimental timescale by suppressing three-body losses. [Preview Abstract] |
Friday, May 27, 2016 12:06PM - 12:18PM |
U6.00009: ABSTRACT WITHDRAWN |
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