Bulletin of the American Physical Society
49th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics APS Meeting
Volume 63, Number 5
Monday–Friday, May 28–June 1 2018; Ft. Lauderdale, Florida
Session K03: Quantum Gases in Low Dimensions 
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Chair: David Weiss, Penn State University Room: Grand B 
Wednesday, May 30, 2018 2:00PM  2:12PM 
K03.00001: Dynamical fermionization of the momentum distribution of a 1D Bose gas Joshua Wilson, Neel Malvania, Yicheng Zhang, Wei Xu, Lin Xia, Marcos Rigol, David Weiss When a harmonic trap confining a 1D Bose gas in the TonksGiardeau limit is suddenly turned off, the initially peaked momentum distribution evolves as it expands in 1D. It ultimately becomes indistinguishable from the momentum distribution of a noninteracting Fermi gas in the original harmonic trap.[1,2] We observe this phenomenon in a bundle of 1D tubes and compare the result to a hard core boson calculation using the experimental trap parameters. We also observe the related dynamics of bosons in a trap after a sudden change of trap depth. [1] In this case, the momentum distribution evolves from bosonic to fermionic, and back, two times per oscillation period. [1]A. Minguzzi, D.M. Gangardt, PRL 94, 240404 (2005) [2]M. Rigol, A. Muramatsu, PRL 94, 240403 (2005) [Preview Abstract] 
Wednesday, May 30, 2018 2:12PM  2:24PM 
K03.00002: Formation of bright matterwave breathers D. Luo, J. H. V. Nguyen, P. Bagge, R. G. Hulet Solitons are 1D nonlinear waves that propagate without changing their shape. In recent years, solitons in quasi1D matterwave systems have been investigated extensively. The nonlinearity in these systems can also give rise to a bound state of two solitons, known as a breather. It is also nondispersive, but its density profile is periodic in time, oscillating at the frequency given by the chemical potential difference between the two solitons. We report the creation of a breather by first forming a bright matterwave soliton from a BoseEinstein condensate of $^7$Li atoms in a quasi1D trap. Then we quench the scattering length by a factor of 4 to create a 1:3norm ratio breather. We measure the breather frequency as a function of the trap aspect ratio. We plan to explore the breather interaction with a potential barrier, which has been predicted to have a quantized tunneling ratio\footnote{V. Dunjko and M. Olschanii, arXiv:1501.00075 (2015)}. In addition, we plan to study the predicted spontaneous dissociation of breathers due to quantum manybody effects\footnote{V. A. Yurovsky et al. Phys. Rev. Lett. 119, 220401 (2017)}. [Preview Abstract] 
Wednesday, May 30, 2018 2:24PM  2:36PM 
K03.00003: Complex Networks on Quantum States Lincoln D. Carr, Marc Andrew Valdez, Daniel Jaschke, David L. Vargas, Bhuvanesh Sundar, Kaden Hazzard We quantify the emergent complexity of quantum states near quantum critical points on regular 1D lattices, via complex network measures based on quantum mutual information as the adjacency matrix, in direct analogy to quantifying the complexity of EEG/fMRI measurements of the brain. Using matrix product state methods, we show that network density, clustering, disparity, and Pearson's correlation obtain the critical point for both quantum Ising and BoseHubbard models to a high degree of accuracy in finitesize scaling for three classes of quantum phase transitions, $Z_2$, mean field superfluid/Mott insulator, and a BKT crossover. Moreover, they uncover new kinds of structure in the quantum critical region not visible in correlation length and other established measures. For the Ising model we then analytically explore the effect of temperature on the complex network structure, covering mutual information, twopoint correlations, and Renyi entropies, and find reentrant behavior in the quantum critical fan. [Preview Abstract] 
Wednesday, May 30, 2018 2:36PM  2:48PM 
K03.00004: Correlation induced localization of lattice trapped bosons coupled to a BoseEinstein condensate Peter Schmelcher, Kevin Keiler, Sven Kroenke We investigate the ground state properties of a lattice trapped bosonic system coupled to a LiebLiniger type gas. Our main goal is the exploration and analysis of the twospecies manybody quantum system including all relevant correlations beyond the standard meanfield approach. To achieve this, we use the MultiConfiguration TimeDependent Hartree method for Mixtures (MLMCTDHX). Increasing the lattice depth and the interspecies interaction strength, the wave function undergoes a transition from an uncorrelated to a highly correlated state, which manifests itself in the localization of the lattice atoms in the latter regime. For small interspecies couplings, we identify the process responsible for this crossover in a singleparticlelike picture. Moreover, we give a full characterization of the wave function's structure in both regimes, using Bloch and Wannier states of the lowest band, and we find an order parameter, which can be exploited as a corresponding experimental signature. To deepen the understanding, we use an effective Hamiltonian approach, which introduces an induced interaction and is valid for small interspecies interaction. We finally compare the ansatz of the effective Hamiltonian with the results of the MLMCTDHX simulations. [Preview Abstract] 
Wednesday, May 30, 2018 2:48PM  3:00PM 
K03.00005: Quasimomentum distribution and expansion of an anyonic gas Dario Juki\'{c}, Tena Dub\v{c}ek, Bruno Klajn, Robert Pezer, Hrvoje Buljan We point out that the momentum distribution is not a proper observable for a system of anyons in two dimensions. In view of anyons as Wilczek's composite charged flux tubes, this is a consequence of the fact that the orthogonal components of the kinetic momentum operator do not commute at the position of a flux tube, and thus cannot be diagonalized in the same basis. As a substitute for the momentum distribution of an anyonic (spatially localized) state, we propose to use the asymptotic singleparticle density after the expansion of anyons in free space from the state. This definition is identical to the standard one when the statistical parameter approaches that for bosons or fermions. Exact examples which underpin our proposal are shown. They reveal that the quasimomentum distribution can be used to identify anyonic statistics in standard timeofflight measurements. [Preview Abstract] 
Wednesday, May 30, 2018 3:00PM  3:12PM 
K03.00006: Entanglement induced interactions in binary mixtures Jie Chen, Johannes Schurer, Peter Schmelcher We establish a conceptual framework for the identification and the characterization of induced interactions in binary mixtures and reveal their intricate relation to entanglement between the components or species of the mixture. Exploiting an expansion in terms of the strength of the entanglement among the two species, enables us to deduce an effective singlespecies description. In this way, we naturally incorporate the mutual feedback of the species and obtain induced interactions for both species which are effectively present among the particles of same type. Importantly, our approach incorporates fewbody and inhomogeneous systems extending the scope of induced interactions where two particles interact via a bosonic bathtype environment. Employing the example of a onedimensional spinpolarized ultracold BoseFermi mixture, we obtain induced BoseBose and FermiFermi interactions with shortrange attraction and longrange repulsion. With this, we show how beyond species meanfield physics visible in the twobody correlation functions can be understood via the induced interactions. [Preview Abstract] 
Wednesday, May 30, 2018 3:12PM  3:24PM 
K03.00007: Quantum Droplet of OneDimensional Bosons with a Threebody Attraction Yuta Sekino, Yusuke Nishida We study onedimensional bosons with a weak threebody attractive interaction and show that they form a manybody droplet stabilized by asymptotic freedom of the system [1]. The ratio of the binding energy of the droplet to that of three bosons are universal and grow exponentially as the number of bosons increases. The realization of our system with coupled twocomponent bosons in an optical lattice is also discussed [1,2]. [1] Y. Sekino and Y. Nishida, accepted as a Rapid Communication in Phys. Rev. A. [2] D. S. Petrov, Phys. Rev. A 90, 021601(R) (2014). [Preview Abstract] 
Wednesday, May 30, 2018 3:24PM  3:36PM 
K03.00008: Measurement of the Dynamic Structure Factor of a Strongly Interacting 1D Fermi Gas YaTing Chang, Tsung Lin Yang, Pjotrs Grisins, Zhenghao Zhao, ChungYou Shih, Thierry Giamarchi, Randall G. Hulet An interacting Fermi gas in one dimension (1D) cannot be explained by the familiar Landau Fermi liquid theory since excitations are collective, rather than quasiparticle excitations. Instead, such a system can be described by TomonagaLuttinger liquid (TTL) theory, where excitations near the Fermi surface are characterized by a linear, soundlike spectrum having different speeds for spin and charge waves. We present measurements of the dynamical structure factor $S(q,\omega)$ of an interacting 1D Fermi gas. We confine a spin1/2 system of $^6$Li atoms to 1D by using a 2D optical lattice. Bragg spectroscopy is used to measure the response of the gas to density ("charge") mode excitations at momentum $q$ and frequency $\omega$. By fixing $q$ at $q_0$ and varying $\omega$, we obtain the spectrum $S(q_0, \omega)$. We vary the strength of the repulsive interactions using a Feshbach resonance. [Preview Abstract] 

K03.00009: ABSTRACT WITHDRAWN 
Wednesday, May 30, 2018 3:48PM  4:00PM 
K03.00010: TwoBody Relaxation of Fermions in 1D near a PWave Resonance Arif Mawardi Ismail, Andrew Marcum, Francisco Fonta, Kenneth O'Hara Degenerate Fermi gases with pwave interactions hold many exciting prospects for observing novel quantum phases of matter. Dilute ultracold gases were thought to be an ideal platform to study such phenomena as pwave interactions can be strongly and controllably enhanced near a magnetically tunable pwave Feshbach resonance. Unfortunately, the enhancement of the pwave interaction strength near a Feshbach resonance has been accompanied by a corresponding strong enhancement of twobody and threebody inelastic collision rates which leads to significant atom loss on short time scales. Recently, however, it has been predicted that twobody and threebody decay can be significantly reduced as the dimension of the system is decreased (see Kurlov & Shlyapnikov, PRA 95, 032710 (2017)). Indeed, a study of twobody decay near a pwave resonance in 2D has already shown a significant reduction (Waseem et al, PRA 96, 062704 (2017)). Here, we study the twobody decay of the same twocomponent mixture of fermions but in one dimensions (1D). In 1D, the reduction in the two and threebody decay rate is expected to be much more significant, perhaps so much so that it would allow for oddwave superfluid pairing in a 1D Fermi gas. [Preview Abstract] 
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