Bulletin of the American Physical Society
51st Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 65, Number 4
Monday–Friday, June 1–5, 2020; Portland, Oregon
Session J03: LongRange or Anisotropic Interactions in Cold GasesLive

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Chair: John Bohn, University of Colorado, Boulder Room: D135136 
Wednesday, June 3, 2020 2:00PM  2:12PM Live 
J03.00001: Spin squeezing in the XXZ model with powerlaw interactions Chunlei Qu, Michael A. Perlin, Ana M. Rey Spin squeezed states are known to be a useful resource for quantum metrology. Although there have been many proposals on how to generate spin squeezing, most of the dynamical generations involve collective Ising interactions via the socalled one axis twisting (OAT) model. In this talk, we will present our recent results on spin squeezing generation in the XXZ model with powerlaw interactions. Despite the inhomogeneous character of the spin couplings, we find this system can exhibit a level of spinsqueezing similar to that generated by the OAT model. We will report on our systematic investigation of this model and explain the mechanism responsible for the large spin squeezing generation. Our results are useful for stateoftheart ultracold polar molecular experiments where pinned molecules in an optical lattice can interact with each other by longrange dipolar interactions and for trapped ion crystals featuring longrange interactions mediated by the phonon modes of the crystal. [Preview Abstract] 
Wednesday, June 3, 2020 2:12PM  2:24PM Live 
J03.00002: TransverseField Ising Dynamics by Rydberg Dressing Ognjen Markovic, Victoria Borish, Jacob Hines, Shankari Rajagopal, Monika SchleierSmith Optical control of atomic interactions is a powerful tool for studying quantum manybody physics. I will present recent results on generating longrange Ising interactions between groundstate atoms by Rydberg dressing, i.e., coupling to Rydberg states with an offresonant laser field. We perform Rydberg dressing on a cold dilute gas of cesium atoms and measure the resulting meanfield dynamics via Ramsey spectroscopy, detecting characteristic oneaxis twisting dynamics. We additionally emulate a transversefield Ising model by adding a periodic microwave drive and detect dynamical signatures of the ferromagneticparamagnetic phase transition. This work paves the way for future studies ranging from creating arrays of spinsqueezed states via local optical control to investigating Floquet phases in spin chains with periodically driven interactions. [Preview Abstract] 
Wednesday, June 3, 2020 2:24PM  2:36PM Live 
J03.00003: Imaging Protection of Spin Coherence in a Tunable Heisenberg Model Eric S. Cooper, Emily J. Davis, Avikar Periwal, Gregory Bentsen, Simon J. Evered, Katherine Van Kirk, Monika H. SchleierSmith Optical cavities can be used to engineer longrange interactions between atomic spins, with diverse applications in metrology and quantum simulation. I will present our recent implementation of a family of Heisenberg spin models, where controlled optical and magnetic fields tune between XY (spinexchange) and Ising interactions. By directly imaging atomic spin states, we characterize the atoms’ interactions and explore the transition between regimes of theoretical interest where inhomogeneities lead to complex manybody states and regimes of metrological interest where the system can be described using a collective spin model. In particular, we show that XY interactions protect the collective spin against inhomogeneous fields that completely dephase the noninteracting system. In future work such interactions can be used to enhance spin squeezing protocols. [Preview Abstract] 
Wednesday, June 3, 2020 2:36PM  2:48PM Live 
J03.00004: Probing a strongly interacting bose mixture with ultralongrange Rydberg molecules J. D. Whalen, S. K. Kanungo, Y. Lu, F. B. Dunning, T. C. Killian Recent work has shown that photoexcitation of ultralong range Rydberg molecules (ULRRMs) proivdes an \textit{in situ} probe of spatial correlations in quantum gases. The excitation rate of the groundstate dimer ULRRM is proportional to the nonlocal pair correlation function $g^{(2)}(R)$, with $R$ tunable from roughly $14003200$ $a_0$ by changing the principal quantum number, $n$, of the target Rydberg state [1]. At these length scales, the pair correlation function for a weakly interacting gas is largely determined by the thermal de Broglie wavelength and the symmetry of the manybody wavefunction under particle exchange. In the presence of strong interparticle interactions, however, $g^{(2)}(R)$ reflects the shape of the scattering wavefunction at short range, and a node in the wavefunction leads to a zero in the paircorrelation function at a separation around the swave scattering length, $a_s$. We present measurements of the excitation rate of ULRRM dimers in a strongly interacting mixture of $^{88}$Sr and $^{84}$Sr ($a_s=1800\,a_0$) and progress in our efforts to observe the effect of strong interactions on the pair correlation function $g^{(2)}(R)$.\\\\$[1]$ J. D. Whalen, et al. Phys. Rev. A \textbf{100}, 011402(R) [Preview Abstract] 
Wednesday, June 3, 2020 2:48PM  3:00PM Live 
J03.00005: A protocol to realize triatomic ultralong range Rydberg molecules in an ultracold KRb gas Rosario GonzalezFerez, Seth T. Rittenhouse, Peter Schmelcher, H.R. Sadeghpour Ultralongrange polyatomic Rydberg molecules might be formed when a heteronuclear diatomic molecule is bound to a Rydberg atom [1]. The binding mechanism appears due to the anisotropic scattering of the Rydberg electron from the permanent electric dipole moment of the polar molecule. We propose an experimentally realizable scheme to produce these triatomic ultralongrange Rydberg molecules in ultracold KRb traps, which might use the excitations of both postassium or rubidium atoms. By exploiting the Rydberg electronmolecule anisotropic dipole interaction, we induce a near resonant coupling of the nonzero quantum defect Rydberg levels with the KRb molecule in N=0 and N=2 rotational levels. This coupling enhances the binding of the triatomic ultralongrange Rydberg molecule and produces favorable FranckCondon factors [2]. [1] R. GonzalezFerez et al, New J. Phys. {\bf 17}, 013021 (2015). [2] R. GonzalezFerez et al, J. of Phys. B.: At. Mol. Opt. Phys. in press(2020). [Preview Abstract] 
Wednesday, June 3, 2020 3:00PM  3:12PM Live 
J03.00006: Universal relationships of spectroscopic constants for diatomic molecules Xiangyue Liu, Jesus PerezRios The systematic study of spectroscopic constants in diatomic molecules has been of interest in the atomic, molecular, and optical physics community since the birth of quantum chemistry. However, such a task has never been undertaken within the paradigm of artificial intelligence. Here, we present a study from a data science perspective, based on machine learning techniques, to elucidate the inherent relationship among the principal spectroscopic constants for diatomic molecules. As a result, it is possible to predict the principal spectroscopic constants of a molecule by looking at the simple atomic properties of the parent atoms. [Preview Abstract] 
Wednesday, June 3, 2020 3:12PM  3:24PM Live 
J03.00007: Hamiltonian engineering in strongly interacting Rydberg systems Nithiwadee Thaicharoen, Sebastian Geier, Titus Franz, Andre Salzinger, Annika Tebben, Clement Hainaut, Gerhard Zuern, Matthias Weidemueller We demonstrate an ability to engineer Hamiltonian of manybody Rydberg spin systems using microwave pulse sequences. This allows us to obtain an arbitrary XYZ Heisenberg Hamiltonian out of an original XX Heisenberg Hamiltonian. To quantify this new Hamiltonian, we perform time evolution of our spin system under selected choices of initial state and interaction strength. The results are then compared with numerical simulations to extract the efficiency of the pulse sequences and additional effects. [Preview Abstract] 
Wednesday, June 3, 2020 3:24PM  3:36PM Not Participating 
J03.00008: Calculations of long range interactions for $^{87}$Sr Rydberg states Francis Robicheaux A method for calculating the properties of Rydberg states and RydbergRydberg interaction between two $^{87}$Sr atoms is described.[1] The method is based on a multichannel quantum defect theory (MQDT) description of the Rydberg states that accounts for the hyperfine splitting of the $^{87}$Sr$^+$ ground state. Results are given for the scalar and tensor polarizabilities and the eigenvalues of the $C_6$ matrix for the $5sns$ $F_T=9/2$ series. These results illustrate the new features that arise due to the hyperfine splitting of the thresholds. In particular, there should be several strongly coupled F\"orster resonances above $n=50$ unlike the case of $^{88}$Sr which has none. [1] F. Robicheaux, “Calculations of long range interactions for $^{87}$Sr Rydberg states,” J. Phys. B {\bf 52}, 244001 (2019). [Preview Abstract] 
Wednesday, June 3, 2020 3:36PM  3:48PM Not Participating 
J03.00009: Quantifying the Impact of State Mixing on the Rydberg Excitation Blockade Milo Eder, Tomohisa Yoda, Andrew Lesak, Abigail Plone, Aaron Reinhard The Rydberg excitation blockade has been at the heart of an impressive array of recent achievements in quantum information and simulation. However, statemixing interactions may compromise the effectiveness of the blockade under otherwise favorable conditions. When ultracold atoms are excited to Rydberg states near Forster resonance, up to $\sim $50{\%} of atoms can be found in dipole coupled product states within tens of ns after excitation. There has been disagreement in the literature regarding the mechanism by which this mixing occurs. We use stateselective field ionization spectroscopy to measure, on a shotbyshot basis, the distribution of Rydberg states populated during narrowband laser excitation of ultracold rubidium atoms. Our method allows us to quantify both the number of additional Rydberg excitations added by each mixing event, as well as the extent to which statemixing ``breaks'' the blockade. [Preview Abstract] 
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