Bulletin of the American Physical Society
46th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 60, Number 7
Monday–Friday, June 8–12, 2015; Columbus, Ohio
Session C6: Bosons in Optical Lattices: Entanglement and Topology |
Hide Abstracts |
Chair: David Pekker, University of Pittsburgh Room: Delaware AB |
Tuesday, June 9, 2015 2:00PM - 2:12PM |
C6.00001: Direct measurements of entanglement entropy in one-dimensional bosonic systems Ruichao Ma, Eric Tai, Alexander Lukin, Philipp Preiss, Matthew Rispoli, Rajibul Islam, Markus Greiner The presence of large-scale entanglement is a defining characteristic of exotic quantum phases of matter. However, its experimental verification is an outstanding challenge in condensed matter physics. Within small quantum information processing units, entanglement may be detected via resource-intensive state tomography or class-specific entanglement witnesses. Here, we demonstrate a novel approach to the measurement of entanglement entropy of any bosonic system, using a quantum gas microscope with tailored potential landscapes. We extend the concept of Hong-Ou-Mandel interference from two particles to many-body states. Interfering two copies of identically prepared states measures the quantum mechanical purity of the system and its subsystems, placing bounds on the entanglement entropy. We apply this technique to observe the entanglement dynamics in a few-particle quench of a bosonic system. Our protocol may be applied to any many-body state and provides a new platform for the characterization of strongly correlated states in optical lattices. [Preview Abstract] |
Tuesday, June 9, 2015 2:12PM - 2:24PM |
C6.00002: Quantitative Probes of Entanglement Using Collisional Microscopy Craig Price, Qi Liu, Nathan Gemelke Though entanglement is understood to play a critical role in determining the ground state structure and macroscopic properties of many known physical systems, its definitive quantification has until recently, through the creation of entanglement entropy (EE), spectrum and related measures, escaped a simple definition. Moreover, few if any of these measures have been directly extracted in experiments on strongly correlated matter. In this talk, we present a novel method to measure quantifiers of many-body entanglement by pair-wise entangling a small portion of an atomic gas with an optical-lattice-bound array of secondary atoms serving as quantum-non-destructive probes. For a sample with significant pre-existing long range entanglement, such as in a Bose-Hubbard system near its quantum critical point, the quantum back-action following probe detection affects the sample gas in regions spatially extended beyond where measured. This results in a non-local thermal effect; subsequent measurement of the thermal entropy through the local equation of state can reveal the EE. Quantitative analysis of thermodynamic back action and background effects, such as classical propagation of entropy after a measurement quench, will be discussed. [Preview Abstract] |
Tuesday, June 9, 2015 2:24PM - 2:36PM |
C6.00003: Generation of long-range entanglement in a macroscopic spin singlet Robert J. Sewell, Ferran Martin Ciurana, Giorgio Colangelo, Naeimeh Behbood, Geza Toth, Morgan W. Mitchell We report the generation of long-range entanglement in a macroscopic spin singlet (MSS) [1,2] via collective quantum non-demolition (QND) measurement [3] a global entanglement method predicted [4] to produce entan- glement at all length scales. In a cold $^{87}$Rb spin ensemble of up to $2\times10^6$ atoms, we generate a MSS, entangling at least half of the atoms. Using a gradient field to convert singlets to triplets, we detect the decay of entanglement in the MSS via spin noise spectroscopy [4] consistent with a mean entanglement length comparable to the size of the atom cloud ($\sim4$mm), three orders of magnitude larger than previously detected in atomic spin systems [5]. [1] N. Behbood {\it et al.}, Phys. Rev. Lett. {\bf 113}, 093601 (2014). [2] G. T\'{o}th and M.W. Mitchell, New J. Phys. {\bf 12}, 053007 (2010). [3] R. J. Sewell {\it et al.}, Nat. Photon. {\bf 7}, 517 (2013). [4] I. Urizar-Lanz {\it et al.}, Phys. Rev. A {\bf 88}, 013626 (2013). [5] D. Greif {\it et al.}, Science {\bf 340}, 1307 (2013). [Preview Abstract] |
Tuesday, June 9, 2015 2:36PM - 2:48PM |
C6.00004: Interspecies entanglement of two-component Bose-Hubbard model Wei Wang, Vittorio Penna, Barbara Capogrosso-Sansone We studied the two-component Bose-Hubbard model by means of perturbation theory. As previously observed numerically, in the presence of a second component, the boundaries of the Mott insulator lobe shift differently on the particle and hole side. In order to explain this observation, we studied the interspecies entanglement. In the calculation, we reduced the computation by considering the group of symmetry operations on the lattice (graph automorphisms). This group partitions the Fock basis into symmetry classes whose contribution to the ground state can be used to give a criterion of entanglement. [Preview Abstract] |
Tuesday, June 9, 2015 2:48PM - 3:00PM |
C6.00005: Growing scheme for topologically ordered states in interacting systems Fabian Letscher, Fabian Grusdt, Michael Fleischhauer We present a protocol for growing states with topological order in interacting many-body systems. The basic ingredients are explained using the superlattice Bose-Hubbard model as a simple toy model. Firstly, a topologically protected Thouless pump is used to create a local quasi-hole excitation. Secondly, a coherent pump refills the quasi-hole excitation with a single particle by making use of a blockade mechanism due to the repulsive interaction between the particles. In finite systems with dispersive bands, we discuss extensions to the protocol to maintain a high efficiency. The scheme can be used to grow the highly correlated Laughlin state in the fractional quantum Hall effect. We use an effective model based on the composite fermion description to simulate large lattice systems with many particles. [Preview Abstract] |
Tuesday, June 9, 2015 3:00PM - 3:12PM |
C6.00006: Topological order in interacting one-dimensional Bose Systems Fabian Grusdt, Michael H\"oning, Michael Fleischhauer We discuss topological aspects of one-dimensional inversion-symmetric systems of interacting bosons, which can be implemented in current experiments with ultra cold atoms. We consider both integer and fractional fillings of a topologically non-trivial Bloch band. Our starting point is the chiral-symmetric Su-Schrieffer-Heeger (SSH) model of non-interacting fermions, which can be realized by hard-core bosons. When the hard-core constraint is removed, we obtain a bosonic system with inversion-symmetry protected topological order. Because the chiral symmetry is broken by finite interactions, the bulk-boundary correspondence of the SSH model is no longer valid. Nevertheless we show that the fractional part of the charge which is localized at the edge can distinguish topologically trivial- from non-trivial states. We generalize our analysis by including nearest neighbor interactions and present a topological classification of the resulting quarter-filling Mott insulating phase. In this case fractionally charged bulk excitations exist, which we identify in the grand-canonical phase diagram. [Preview Abstract] |
Tuesday, June 9, 2015 3:12PM - 3:24PM |
C6.00007: Detecting spin-entanglement dynamics with a quantum microscope Manuel Endres, Leonardo Mazza, Davide Rossini, Rosario Fazio, Takeshi Fukuhara, Sebastian Hild, Peter Schauss, Immanuel Bloch, Christian Gross In a first theory part, I will present new experimentally measurable lower bounds for the two-site entanglement of the spin-degrees of freedom of many-body systems with local particle-number fluctuations. The method aims at enabling the spatially resolved detection of spin-entanglement in Hubbard systems using high-resolution imaging in optical lattices. More generally, the scheme can simplify the entanglement detection in ion chains, Rydberg atoms, or similar atomic systems. Concerning the experimental implementatioin, I will present progress towards the observation of entanglement generation and spreading during spin impurity dynamics. Main reference: Leonardo Mazza~\textit{et al}~2015~\textit{New J. Phys.}~\textbf{17 }013015 [Preview Abstract] |
Tuesday, June 9, 2015 3:24PM - 3:36PM |
C6.00008: Entangled Dynamics of the Transverse Quantum Ising Model at Finite Temperature Daniel Jaschke, Kenji Maeda, Wei Han, Tommaso Calarco, Simone Montangero, Lincoln D. Carr An outstanding question in entangled dynamics of quantum phase transitions is the role of finite temperature. We study this problem in the context of ultracold molecules in optical lattices, which exhibit the tranverse quantum Ising model. We use both time-dependent matrix product density operator (MPDO) and matrix-product-state (MPS) methods based on tensor networks to compare zero and finite temperature dynamics, the latter represented by the Gibbs distribution. Explorations include local and global quantum quenches and the spreading of correlations. [Preview Abstract] |
Tuesday, June 9, 2015 3:36PM - 3:48PM |
C6.00009: Probe knots and Hopf insulators with ultracold atoms Dong-Ling Deng, Sheng-Tao Wang, Kai Sun, Lu-Ming Duan Knots and links are fascinating and intricate topological objects that have played a prominent role in physical and life sciences. Their influence spans from DNA and molecular chemistry to vortices in superfluid helium, defects in liquid crystals and cosmic strings in the early universe. Here, we show that knotted structures also exist in a peculiar class of three dimensional topological insulators---the Hopf insulators. In particular, we demonstrate that the spin textures of Hopf insulators in momentum space are twisted in a nontrivial way, which implies various knot and link structures. We further illustrate that the knots and nontrivial spin textures can be probed via standard time-of-flight images in cold atoms as preimage contours of spin orientations in stereographic coordinates. The extracted Hopf invariants, knots, and links are validated to be robust to typical experimental imperfections. Our work establishes the existence of knotted structures in cold atoms and may have potential applications in spintronics and quantum information processings. [Preview Abstract] |
Tuesday, June 9, 2015 3:48PM - 4:00PM |
C6.00010: On demand generation of 1D topological chains with Majorana fermions in 2D non-topological optical lattices Lei Jiang, Chuanwei Zhang Majorana fermion appears near the topological phase boundary. In 2D, Majorana fermions are proposed when vortices, which stand for topological defects, are formed in topological superfluids only with Rashba spin-orbit coupling. Majorana fermions are not easily achievable in 2D cold atom systems. In our work, we show, by imprinting 1D local potentials in a finite 2D system, we can realize a 1D topological chain on demand even in originally non-topological 2D systems. A pair of zero-energy Majorana fermions can be stable in this system and exists at the ends of the topological chain. We also demonstrate the possibility to arrange an array of Majorana fermions by separating topological chains with non-topological ones. Compared with strictly 1D systems, quantum fluctuations are strongly suppressed in such high dimensional optical lattices. Because all requirements of our model are within the reach of current experiments, our proposed scheme may provide an experimental feasible platform for observing Majorana states in 2D ultra-cold atom optical lattices. [Preview Abstract] |
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