Bulletin of the American Physical Society
2013 Joint Meeting of the APS Division of Atomic, Molecular & Optical Physics and the CAP Division of Atomic, Molecular & Optical Physics, Canada
Volume 58, Number 6
Monday–Friday, June 3–7, 2013; Quebec City, Canada
Session P7: Collective Effects in Atom-light Interactions |
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Chair: Jacob Sherson, University of Aarhus Room: 303 |
Thursday, June 6, 2013 2:00PM - 2:12PM |
P7.00001: Collective shifts and frequency chirping in a superradiant system Guin-Dar Lin, Susanne Yelin In quantum optics, the energy shift and the stimulated emission rate are Kramers-Kronig pairs. Therefore when a superradiant system is considered, the cooperatively enhanced decay rate results in collective shifts and hence frequency chirping during the decay process. This effect, including the so-called collective Lamb shift, is investigated under a framework of two-body effective description, where we take into account the actual contribution of dipole-dipole interaction and inter-particle coherence. [Preview Abstract] |
Thursday, June 6, 2013 2:12PM - 2:24PM |
P7.00002: Characterizing collective spontaneous emission in simple geometries Yi Li, Juha Javanainen Under suitable conditions, notably the absence of saturation, the collective response of atoms to light may be simulated numerically, in principle exactly, by applying classical electromagnetism to a medium of model atoms with a dipole moment linear in the driving light. In spite of being entirely classical, such an analysis correctly accounts for collective spontaneous emission in the atomic sample. We report on quantitative characterization of spontaneous emission in atomic samples with simple geometries such as a spherically symmetric Gaussian cloud and a two-dimensional sheet. Collective effects are seen at unexpectedly low atom densities, with $n(\lambda/2\pi)^3\ll1$. [Preview Abstract] |
Thursday, June 6, 2013 2:24PM - 2:36PM |
P7.00003: Stability and Cavity Feedback in a Superradiant Raman Laser Justin G. Bohnet, Joshua M. Weiner, Kevin C. Cox, Zilong Chen, James K. Thompson We experimentally study the amplitude stability properties of a superradiant laser operating deep into the bad-cavity regime of laser physics using a cold-atom $^{87}$Rb Raman laser. Deep in the bad-cavity regime, the stimulation of light can be viewed as arising from the self-synchronization of the optical dipoles within the atomic ensemble. Here, we study the dynamics of the atomic ensemble's collective Bloch vector when subjected to external perturbations. This is achieved by combining measurements of the laser light field's amplitude, non-demolition measurements of the atomic populations, and fast dynamic control of the superradiant emission enabled by the Raman transition. In addition to characterizing the stability of the system using a simple model based on the optical Bloch equations for the laser, we observe that the dispersive coupling of the atomic inversion to the cavity resonance frequency provides a feedback mechanism that can either enhance or diminish the amplitude stability of the laser. These results will guide future development of superradiant lasers with ultranarrow linewidths. [Preview Abstract] |
Thursday, June 6, 2013 2:36PM - 2:48PM |
P7.00004: Dispersive optical non-linearity at the single-photon level Ofer Firstenberg, Thibault Peyronel, Qi-Yu Liang, Alexey Gorshkov, Mikhail Lukin, Vladan Vuletic Realizing and engineering optical non-linearity at the level of single photons is a goal of scientific and technological significance, pertaining to non-classical light sources, all-optical switches and phase gates, and correlated many-photon states. We obtain strong interaction between propagating photons by coupling them to high-laying Rydberg levels in an atomic gas. The resulting ``Rydberg polaritons'' possess a large electric dipole-moment and interact via the Van-der-Waals forces, while slowly traversing the medium. The interaction potential can be varied from real to imaginary; consequently, the dynamics of the two-photon wavefunction varies from dispersive (Schrodinger-like) to dissipative (diffusion-like). To characterize the final two-photon state, we use time-dependent tomography, and by that delineate the two-photon bound-state. We observe strong bunching and anti-bunching, and large conditional phase-shifts, with an effective interaction range much larger than the Van-der-Waals blockade range. [Preview Abstract] |
Thursday, June 6, 2013 2:48PM - 3:00PM |
P7.00005: All-Optical Switching in an Add-Drop Resonator using Two-Photon Absorption in Warm Rubidium Vapor Chad Weiler, Scott Hendrickson, Ryan Camacho, Peter Rakich, Jonathan Cox, Michael Shaw, Todd Pittman, James Franson, Bryan Jacobs The need for low-power optical switching in the fields of quantum information and classical logic has been well documented. Here we present results showing all-optical switching using a Si$_3$N$_4$ micro-disk cavity, in an add/drop configuration, evanescently coupled to hot Rubidium (Rb) vapor. The atomic vapor only dissipates the energy in the cavity when control and signal frequencies sum to a Rb two-photon S-P-D transition. This suppresses the cavity build-up and alters the output path of the signal light. Devices of this type can exhibit fast switching times with ultra-low energy dissipation which make them viable technologies for application in classical logic or quantum information processing. [Preview Abstract] |
Thursday, June 6, 2013 3:00PM - 3:12PM |
P7.00006: Scalable generation of multiple quantum correlated beams from hot rubidium vapors Jietai Jing, Zhongzhong Qin, Hailong Wang, Jia Kong, Leiming Cao, Weiping Zhang Quantum correlation and quantum entanglement shared among multiple quantum nodes are the fundamental ingredients for the future quantum internet. In order to make an efficient quantum interface between multi-mode quantum light sources and the atomic ensemble which has been proven to be a good candidate for quantum memory and quantum repeater, it is necessary to generate the multimode quantum light sources which match the atomic transition lines of the atomic ensemble. Here we present a scalable method for generating the multiple quantum correlated beams by using multiple four wave mixing processes in hot Rubidium vapor and we experimentally showed that the strong quantum correlation among the three bright beams. Their relative intensity difference is -5.6dB below the correspondent shot noise limit and the squeezing from only one vapor cell in such system is -3.5dB. This result agrees with our theoretical prediction that the quantum correlation in our scheme increases as the number of quantum modes increases. Our method also has the advantages of scalability and potential applications in producing multipartite quantum entangled images. [Preview Abstract] |
Thursday, June 6, 2013 3:12PM - 3:24PM |
P7.00007: Efficient Frequency Translation via Bragg Scattering in Rb-Filled Photonic Band-Gap Fibers Prathamesh Donvalkar, Vivek Venkataraman, Stephane Clemmen, Kasturi Saha, Alexander Gaeta Bragg scattering via the nonlinear process of four-wave mixing is a promising approach to manipulate the frequency content of photonic quantum states. Here we report the first experimental demonstration of frequency translation from a signal to an idler wave at microwatt pump power levels in Rubidium vapor confined to hollow core photonic band gap fibers using Bragg scattering. Conversion at lower powers is facilitated by generating optical depths of around 100 in the fibers resulting in large nonlinear susceptibilities. We employ a four wave mixing scheme using the 5S$_{1/2} \to $ 5D$_{3/2}$ two-photon transition in $^{85}$Rb. The continuous-wave pump beams are tuned to the D2 and D1 lines at 780 nm and 795 nm respectively. A weak signal beam tuned near the 5P$_{3/2} \to $ 5D$_{3/2}$ transition at 776 nm is translated to a wavelength of 761 nm, corresponding to the 5P$_{1/2} \to $ 5D$_{3/2}$ transition. Conversion of 12{\%} for this 15-nm translation is achieved at pump powers as low as 40 $\mu $W, which is more than 3 orders of magnitude lower than previously reported for solid-state waveguides. [Preview Abstract] |
Thursday, June 6, 2013 3:24PM - 3:36PM |
P7.00008: Generation of a Coherent, Continuous-Wave Spectrum with Two Octaves of Optical Bandwidth Joshua Weber, Deniz Yavuz From a single input laser, we generate roughly 30 output beams with linewidths on the order of 10 kHz whose wavelengths range from 800 nm to 3.2 microns, nearly two octaves of optical bandwidth. We use continuous-wave (CW) stimulated Raman scattering inside a deuterium-filled, high-finesse cavity as a wavelength-independent molecular modulator for optical light. CW laser beams, whose frequency difference is slightly detuned from a molecular Raman resonance, are used to drive vibrational and rotational transitions in deuterium. The high intensity of these fields inside the cavity induces coherent rotations and vibrations, and in this coherent state the molecules act as a CW modulator. The modulation frequencies, which correspond to vibrational and rotational transitions in molecular deuterium, range from 5 to 90 THz. [Preview Abstract] |
Thursday, June 6, 2013 3:36PM - 3:48PM |
P7.00009: Generating controllable frequency-comb-like structures in terahertz range via Rabi sidebands Alex Filin, Dmitri Romanov, Robert Levis When broad, coherent Rabi sidebands are invoked by a moderately intense picosecond laser pulse, they typically exhibit spectral interference fringes. We demonstrate the possibility of controlling this fringe pattern toward a comb-like structure. We investigated the influence of the driving pulse (normalized to 1 ps FWHM) shape parameters on the structural characteristics of the sideband spectra: the spectrum envelope, the fringe contrast, and the fringe spacing variation. The envelope was found to depend drastically on the sharpness of the driving pulse, that is, on the rate at which the temporal distance between the leading and trailing edges grows away from the pulse maximum. Increase in this parameter effectively flattens the envelope. The fringe contrast, that is, the maximum-to-minimum difference, depends strongly on the asymmetry of the driving pulse. The imbalance between the driving and the trailing edges leads to fast decrease of the contrast. The variation of inter-peak distance within a sideband was controlled using super-Gaussian shape of the driving pulse. While for the Gaussian pulse the inter-peak distance increases almost 5 times over the interval from 1.60 to 1.66 eV (in the case of oxygen), sufficiently super-Gaussian shape leads to almost equidistant fringes (comb-like spectrum). [Preview Abstract] |
Thursday, June 6, 2013 3:48PM - 4:00PM |
P7.00010: ABSTRACT WITHDRAWN |
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