Bulletin of the American Physical Society
Joint Fall 2012 Meeting of the Texas Sections of the APS, AAPT, and Zone 13 of the SPS
Volume 57, Number 10
Thursday–Saturday, October 25–27, 2012; Lubbock, Texas
Session E4: Atomic, Molecular, and Optical Physics I |
Hide Abstracts |
Chair: Wallace Glab, Texas Tech University Room: Holiday Inn Towers University A |
Friday, October 26, 2012 3:30PM - 3:42PM |
E4.00001: Phase Manipulating Refractive Index form Positive to Negative in a Four-level Atomic System Hongjun Zhang We propose a four-level loop atomic scheme based on quantum coherence. Electric and magnetic responses of the medium to the probe field are discussed by taking into account the relative phase of the applied fields. It is shown that a change of the refractive index from positive to negative can occur by modulating the relative phase of the applied fields under suitable conditions. Then the medium can be switched from positive-index material to negative-index material or vice verse. In addition, a negative index material can be realized in different frequency regions by adjusting the relative phase. [Preview Abstract] |
Friday, October 26, 2012 3:42PM - 3:54PM |
E4.00002: Topological phase transitions of attractive fermions with spin-orbit coupling in an optical lattice Chunlei Qu, Ming Gong, Chuanwei Zhang It has been shown by Zhang et al [Chuanwei Zhang et al, Phys. Rev. Lett. 101, 160401 (2008)] that an effective px + ipy order can be created from a conventional s-wave pairing with spin-orbit coupling and Zeeman field, two essential ingredients that have already been realized in experiments by Spielman's group at NIST. The same idea has been extended to semiconductor nanowires to search for the Majorana Fermions, which is a basic building block for the fault-tolerant topological quantum computation. Here we studied the the spin-orbit coupled Fermi gas in a one dimensional optical lattice with finite length in the mean field theory. In our model, the s-wave interaction induced Hartree shift term has been included. We solve the Bogoliubov-de-Gennes (BdG) equation self-consistently and find that the Hartree shift and the spin-orbit coupling can greatly enlarge the topological phase area in the $h-\mu$ phase diagram. We derive an exact expression for the topological quantum phase transition. We also show that the end of the optical lattice plays an important role in the formation of topological superfluid in our model. [Preview Abstract] |
Friday, October 26, 2012 3:54PM - 4:06PM |
E4.00003: Searching for Majorana Fermions in 2D Spin-orbit Coupled Fermi Superfluids at Finite Temperature Ming Gong, Gang Chen, Suotang Jia, Chuanwei Zhang Recent experimental breakthrough in realizing spin-orbit (SO) coupling for cold atoms has spurred considerable interest in the physics of 2D SO coupled Fermi superfluids, especially topological Majorana fermions (MFs) which were predicted to exist at zero temperature. However, it is well known that long-range superfluid order is destroyed in 2D by the phase fluctuation at finite temperature and the relevant physics is the Berezinskii-Kosterlitz-Thouless (BKT) transition. In this Letter, we examine finite temperature effects on SO coupled Fermi gases and show that finite temperature is indeed necessary for the observation of MFs. MFs are topologically protected by a quasiparticle energy gap which is found to be much larger than the temperature. The restricted region for the observation of MFs have been obtained. Phys. Rev. Lett. In Press. [Preview Abstract] |
Friday, October 26, 2012 4:06PM - 4:18PM |
E4.00004: Route to Observable Fulde-Ferrell-Larkin-Ovchinnikov Phases in 3D Spin-Orbit Coupled Degenerate Fermi Gases Chuanwei Zhang, Ming Gong, Zhen Zheng, Xubo Zhou, Guangcan Guo The Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) phase, a superconducting state with non-zero total momentum Cooper pairs in a large magnetic field, was first predicted about 50 years ago, and since then became an important concept in many branches of physics. In recent years, the possibility of observing FFLO states using ultracold degenerate Fermi gases has sparked tremendous interest. However, unambiguous experimental evidence for FFLO states is still elusive because of the stringent parameter requirement in experiments. In this Letter, we show that a giant parameter region for FFLO states can be obtained in 3D degenerate Fermi gases in the presence of spin-orbit coupling and an in-plane Zeeman field, two ingredients that were already developed for cold atoms in recent experiments. The predicted FFLO state is stable against quantum fluctuations due to the 3D geometry, and can be observed with experimentally already achieved temperature (T~0.05E\_F). [Preview Abstract] |
Friday, October 26, 2012 4:18PM - 4:30PM |
E4.00005: Generation of high frequency coherent light by means of superradiant parametric resonance Anatoly Svidzinsky, Luqi Yuan Extended atomic ensembles excited collectively act as a cavity for photons resonant with the atomic frequency $\omega $. In such a system the energy of electromagnetic field goes back and forth between the field and the atoms on a superradiant time scale determined by the collective frequency $\Omega $ $<<\omega $. We show that if atomic ensemble is driven by a laser with frequency $\Omega $ this can yield exponential grows of the high frequency atomic field in the direction opposite to the propagation direction of the driving field. We demonstrate that using the effect of collective parametric resonance one can, e.g., make a device which converts IR laser beam into XUV coherent light with the gain about 100 per cm. Our findings can lead to development of a new type of table-size coherent sources of XUV and X-ray radiation. [Preview Abstract] |
Friday, October 26, 2012 4:30PM - 4:42PM |
E4.00006: Anomalous switching of optical bistability in a Bose-Einstein condensate Shuai Yang, M. Al-Amri, M. Suhail Zubairy The nonlinear dynamics of the photon number in an optical cavity filled with a cigar-shaped Bose-Enistein condensate is investigated. We find that the way of adding the field is crucial to the switching close to the critical transition point. If the pump field is changed abruptly, the system may jump from one branch to the other even if the pump field intensity has not reached the critical transition point yet. This behavior is similar to the anomalous switching in the dispersive optical bistability. [Preview Abstract] |
Friday, October 26, 2012 4:42PM - 4:54PM |
E4.00007: Nonlocal effects in light emission by N atoms: collective eigenstates and their decay rates Xiwen Zhang, Anatoly Svidzinsky, Luqi Yuan Collective emission of light by atomic ensembles yields fascinating phenomena of superradiance and radiation trapping even at the single photon level. Here we discuss how time retardation caused by the finite value of the speed of light modifies collective evolution of atoms. In particular, we consider spherical geometry and show that nonlocal effects can substantially modify eigenstates of the system and their decay rates for small atomic samples due to large collective Lamb shift in this limit. We also show how cross-over between local (monotonic decay) and non-local (collective oscillations) dynamics occurs for an extended atomic cloud prepared by absorption of a spherical photon. [Preview Abstract] |
Friday, October 26, 2012 4:54PM - 5:06PM |
E4.00008: Coherent control of Casimir force in a chiral medium Jabir Hakami, M. Suhail Zubairy Chirality has been previously reported as a way to observe both attractive and repulsive Casimir forces. Here we propose the coherent control of the Casimir force between two identical atomic chiral media. A magnetic field is applied to a specific example system to split the detuning as well as the refractive indices for the two circularly polarizations, which leads to chirality. It is shown that, by controlling the strength of an external magnetic field, the Casimir force can switch between attractive and repulsive force. [Preview Abstract] |
Friday, October 26, 2012 5:06PM - 5:18PM |
E4.00009: Resonance Fluorescence Localization Microscopy with Subwavelength Resolution Zeyang Liao, M. Al-Amri, M. Suhail Zubairy We evaluate the resonance fluorescence spectrum of a bunch of two-level atoms driven by a gradient coherent laser field. The result shows that we can determine the positions of atoms from the spectrum even when the atoms locate within subwavelength range and the dipole-dipole interaction is significant. This far-field resonance fluorescence localization microscopy method does not require point-by-point scanning and it may be more time-efficient. [Preview Abstract] |
Friday, October 26, 2012 5:18PM - 5:30PM |
E4.00010: Challenging subjects behind using a liquid crystal display as an optical lens Javad R. Gatabi, Wilhelmus Geerts, Dan Tamir Adjustable lenses are widely used in compound optical systems, including cameras and microscopes. Different techniques are used to build lenses with adjustable focusing. One of the recent techniques uses a liquid crystal spatial light modulator (LC-SLM) to generate the adjustable lens phase function. LC-SLMs provide a robust capability to design fast adjustable optical components without any movable mechanical parts. This paper presents a general method to design a compound lens with an adjustable focal length using a LC-SLM for a laser lithography application. The article describes the challenging matters behind using phase modulators in an imaging system. The maximum and minimum accessible focal lengths have been calculated for different LC-SLMs, taking into account the modulator resolution, bit depth and aperture size. A new type of random aberration caused by bit depth limitation is introduced and its dependency on the focal lengths is discussed. The proposed theoretical model to determine the lens parameters is compared with numerical and experimental data. The experimental results agree well with the theory. The focusing capabilities of a Holoeye LC-SLM will be demonstrated. [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