Fall 2007 Atomic Molecular and Optical Physics Seminars @ Stony Brook


Date:   Oct. 15, 2007:  Prof. Markus Greiner, Harvard

Title: “Quantum Gas Microscopy: Towards Lattices with Optical Addressability”


Date: Oct. 22, 2007: Dr. Pascal Naidon, NIST

Title: “Two-Body Transients in Coupled Atom-Molecule Bose-Einstein Condensates”



Ultracold atoms can be associated into diatomic molecules by applying a resonant

laser. This two-body process, known as photoassociation, may be limited at high

laser intensities by the unitarity of the S-matrix. In the case of a Bose-

Einstein condensate of atoms, many-body models have predicted that the

conversion to molecules may be limited at even lower intensities, because of

molecules breaking up into noncondensate atoms, a process called "rogue



In the talk, I will show that there are three regimes of photoassociation in a

Bose-Einstein condensate, and that they all can be understood on the basis of

time-dependent two-body theory. In particular, the rogue dissociation is not a

many-body effect, but results from a "universal" transient response of

individual atom pairs. Finally, I will illustrate how the three regimes could be

observed by photoassociating condensates of alkaline-earth atoms.



Date Oct. 29, 2007: Dr. Ippei Danshita, NIST:

Title: “Quantum Phases of Ultracold Bosons in Double Well Optical Lattices.”


Abstract: Recently, the experimental realization of double-well optical lattices

has attracted much interest [1]. In this talk, I will discuss the superfluid and

insulating phases of bosons in double-well optical lattices and focus on the

specific example of a two-legged ladder, which is currently accessible in

experiments. Applying both mean-field and time-evolving block decimation [2]

techniques to the two-leg Bose-Hubbard Hamiltonian, the zero-temperature phase

diagrams are obtained. The critical points separating the insulating and

superfluid phases at commensurate fillings, where the

Berezinskii-Kosterlitz-Thouless transition occurs, are determined. I will show

that the phase diagram depends significantly on the interchain hopping and tilt

between double wells. In particular, the insulating phase at unit filling

exhibits a non-monotonic behavior as a function of the tilt parameter, producing

a reentrant phase transition between superfluid and insulating phases.


[1] J. Sebby-Strabley et al., Phys. Rev. A 73, 033605 (2006); M. Anderlini et

al., Nature (London) 448, 452 (2007).

[2] G. Vidal, Phys. Rev. Lett. 93, 040502 (2004); ibid. 98, 070201 (2007).



Date: Nov. 5, 2007: Dr. Hua-Gen Yu, BNL

Title: Strategies to Study Large Amplitude Motions in Molecular Spectroscopy


Abstract: Molecules in highly excited vibrational states undergo large amplitude motions (LAM).

These motions often make molecular spectra complicated through the anharmonicity of

potential energy surfaces, and/or the quantum nonadiabatic effects. Therefore, it becomes

a challenge to study the large amplitude motions of molecules in quantum dynamics

calculations, especially, for many-body systems. This is also partially due to the failure of

traditional theories such as the normal mode picture and perturbation approaches. In this

talk, we will discuss a few of strategies to deal with the LAMs for polyatomic molecules.

They include the coherent discrete variable representation (ZDVR)[1], the two-layer

Lanczos iterative diagonalization algorithm[2], and the orthogonal scattering

coordinates[3-4] together with applications.

[1] H.-G. Yu, J. Chem. Phys., 122 (2005) 164107.

[2] H.-G. Yu, J. Chem. Phys., 120 (2004) 2270.

[3] H.-G. Yu, J.T. Muckerman, and T.J. Sears, J. Chem. Phys., 116 (2002) 1435.

[4] H.-G. Yu, and J. T. Muckerman, J. Mol. Spectrosc. 214 (2002) 11.



Date: Nov. 12 and 15, 2007: Prof. Pierre Meystre, University of Arizona (Simons Lecturer)

Nov. 12: Title: “Matter-Wave Superradiance

Nov. 15: Title: “Polar Condensates”






Date: Nov. 26, 2007: Prof. Chris Search, Stevens Institute of Technology

Title:  Spin Current from Quantum Dots Embedded in a Microcavity

Abstract: Experiments with self-assembled quantum dots have recently progressed towards electrical control of the charge state of dots embedded in microcavities. At the same time, a number of experiments have shown strong coupling to a single optical microcavity mode while others have studied the conductance and current noise through self-assembled dots.

These parallel avenues of research have motivated us to study theoretically how electrical transport through a quantum dot would be effected by coupling to a cavity mode. We have developed a model for quantum dots coupled to a lead at zero bias with one of the Zeeman states lying below the Fermi level of the lead and the other above. Raman transitions involving a pump laser and a quantized cavity mode induce spin flips inside the dot that result in a pure spin current flowing from the dot. We have studied the characteristics of the spin current generated by this quantum dot spin battery as well as the associated current noise. The spin current is strongly correlated with the photon current associated with photons leaking out of the cavity as are their associated noise spectra. We find that in our system, the spin current can be significantly larger than for the case of spin flips induced by electron spin resonance. The spin current noise spectra show clear structures that are a result of the discrete nature of photon states in the cavity. For the case of a driven cavity mode, the spin current also exhibits bistability as a function of the laser amplitude that drives the cavity.



Date: Dec. 3, 2007 (4:00 PM in S-141): Ana Maria Rey, Harvard

Title: Quantum magnetism in optical superlattices


Abstract: By loading   spinor atoms in optical lattices it is now possible to

simulate quantum spin models  in  controlled environments and to

study  quantum  magnetism   in  strongly correlated systems. In this talk I will

describe a technique that allows one to prepare,

detect and control superexchange   interactions  in ultra-cold

spinor atoms loaded in optical superlattices. I will focus this

discussion in the context of recent experiments that  measured for the

first time such super-exchange interactions.

  I shall also discuss the many-body dynamics arising from coherent

coupling between singlet-triplet pairs in adjacent double-wells,

in particular the generation of complex magnetic and maximally

entangled   states by non-equilibrium dynamics.



Date: Friday, Dec. 7, 2007 (2:45 PM in S-141) Prof. Anatoly Kuklov, CUNY Staten Island

Title: "Strongly interacting quantum phases of ultracold atomic mixtures in

optical lattices"


I will discuss mixtures of non-convertible atomic species in optical

lattices. The case of integer total filling per site with strong

repulsion may lead to so called supercounterfluidity which finds

analogy in spin systems in the case of two-component mixtures. In

general, it is a state characterized by zero net transfer of atoms

and superfluid counterflows of all species. Depending on

interactions, the order parameter may feature quasi-molecular

complexes consisting of several atomic units and can be characterized

by additional symmetries.  Results of Monte-Carlo simulations for

phase diagram of a two-component bosonic mixture are presented.

Detection scheme relying on the noise analysis of the absorption

image is discussed. Possibilities of inducing phases characterized by

broken lattice symmetries are considered as well.



Date: Friday, Dec. 14, 2007 (3:00 PM in S141): Kyung Soo Choi, Caltech


Title: “A reversible matter-light quantum interface for mapping entanglement”


Abstract: In the field of quantum information science, a considerable activity has been focused on the development of scalable quantum network. A promising architecture for quantum network is composed of quantum nodes for storing and processing information, and photonic channels which link the remote nodes for distributing entanglement [1]. In this talk, I will briefly review progresses towards this goal utilizing the interactions of single photons with atomic ensembles (as a quantum node), and show a recent experimental demonstration of coherent conversion of photonic entanglement into and out of atomic memories. In contrast to (probabilistic) progresses to date, this strategy allows the intrinsically deterministic creation and subsequent state-transfer of the entangled state. Thus, this protocol provides a promising avenue to generate photonic entanglement, and distribute the entanglement between matter and light in a “push-button” fashion for quantum networks.


[1] H. J. Briegel, W. Dur, J. I. Cirac and P. Zoller, Phys. Rev. Lett. 81, 5932 (1998)