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 U7: Coherent Processes in Multi-level Atoms |
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Chair: Michael Gullans, Joint Quantum Institute Room: Delaware CD |
Friday, June 12, 2015 10:30AM - 10:42AM |
U7.00001: Developments in Coherent Perfect Polarization Rotation Michael Crescimanno, James Andrews, Chaunhong Zhou, Michael Baker Coherent Perfect Polarization Rotation (CPR) is a useful technique akin to Coherent Perfect Absorption (CPA, also known as the anti-laser) but that results in very high efficiency optical mode conversion. We describe the analysis of recent experimental data from our CPR testbed, the use of CPR in miniaturizing optical isolators and CPR phenomena in non-linear optics. [Preview Abstract] |
Friday, June 12, 2015 10:42AM - 10:54AM |
U7.00002: Anti-parity-time-symmetry optics in an atomic vapor Peng Peng, Wanxia Cao, Jianming Wen, Liang Jiang, Yanhong Xiao Recently, there has been growing interest to create optical systems with parity-time (PT) symmetry for manipulation of light. A new addition to this line of research is the study of anti-PT-symmetry optics. Unlike a PT symmetry system which requires balanced gain and loss and equal refractive index, the anti-PT symmetry system requires balanced positive and negative refractive index but with the same gain or loss. As in PT-symmetry systems, anti-PT symmetry systems can also display spontaneous phase transition. We have experimentally demonstrated an anti-PT symmetry optical system using a warm atomic vapor cell containing 87Rb. Coupling of two optical modes under Electromagnetically-induced-transparency (EIT) is realized by coherent diffusion of atomic coherence. Our theory predicts that, in a PT-symmetry system, coupling of the two optical channels would increase the gap between their initially separated EIT peaks, but in an anti-PT symmetry system, it would do the opposite. Especially, when the coupling is large enough, the gap vanishes, which indicates that the system is under phase transition. We will report experiment observation of these predictions. [Preview Abstract] |
Friday, June 12, 2015 10:54AM - 11:06AM |
U7.00003: Spinor Slow Light and Two-Color Qubits Ite Yu, Meng-Jung Lee, Julius Ruseckas, Chin-Yuan Lee, Viaceslav Kudriasov, Kao-Fang Chang, Hung-Wen Cho, Gediminas Juzeliunas, Ite A. Yu We report the first experimental demonstration of two-component or spinor slow light (SSL) using a double tripod (DT) atom-light coupling scheme [1]. The scheme involves three atomic ground states coupled to two excited states by six light fields. The oscillation due to the interaction between the two components was observed. SSL can be used to achieve high conversion efficiencies in the sum frequency generation and is a better method than the widely-used double-$\Lambda$ scheme. On the basis of the stored light, our data showed that the DT scheme behaves like the two outcomes of an interferometer enabling precision measurements of frequency detuning. Furthermore, the single-photon SSL can be considered as the qubit with the superposition state of two frequency modes or, simply, as the two-color qubit. We experimentally demonstrated a possible application of the DT scheme as quantum memory/rotator for the two-color qubit. This work opens up a new direction in the EIT/slow light research.\\[4pt] [1] Nature Commun. 5, 5542 (2014). [Preview Abstract] |
Friday, June 12, 2015 11:06AM - 11:18AM |
U7.00004: Electromagnetically Induced Absorption (EIA) and a ``Twist'' on Nonlinear Magneto-optical Rotation (NMOR) with Cold Atoms Paul Kunz, David Meyer, Qudsia Quraishi Within the class of nonlinear optical effects that exhibit sub-natural linewidth features, electromagnetically induced transparency (EIT) and nonlinear magneto-optical rotation (NMOR) stand out as having made dramatic impacts on various applications including atomic clocks, magnetometry, and single photon storage. A related effect, known as electromagnetically induced absorption (EIA), has received less attention in the literature. Here, we report on the first observation of EIA in cold atoms using the Hanle configuration, where a single laser beam is used to both pump and probe the atoms while sweeping a magnetic field through zero along the beam direction. We find that, associated with the EIA peak, a ``twist'' appears in the corresponding NMOR signal. A similar twist has been previously noted by Budker et al., in the context of warm vapor optical magnetometry [1], and was ascribed to optical pumping through nearby hyperfine levels. By studying this feature through numerical simulations and cold atom experiments, thus rendering the hyperfine levels well resolved, we enhance the understanding of the optical pumping mechanism behind it, and elucidate its relation to EIA. Finally, we demonstrate a useful application of these studies through a simple and rapid method for nulling background magnetic fields within our atom chip apparatus. \\[4pt] [1] D. Budker, et al.\textit{ PRL}, vol. 81, no. 26, pp. 5788--5791, Dec. 1998. [Preview Abstract] |
Friday, June 12, 2015 11:18AM - 11:30AM |
U7.00005: Simple and Efficient Single Photon Filter for a Rb-based Quantum Memory Daniel Stack, Xiao Li, Qudsia Quraishi Distribution of entangled quantum states over significant distances is important to the development of future quantum technologies such as long-distance cryptography, networks of atomic clocks, distributed quantum computing, etc.~ Long-lived quantum memories and single photons are building blocks for systems capable of realizing such applications. The ability to store and retrieve quantum information while filtering unwanted light signals is critical to the operation of quantum memories based on neutral-atom ensembles. We report on an efficient frequency filter which uses a glass cell filled with $^{\mathrm{85}}$Rb vapor to attenuate noise photons by an order of magnitude with little loss to the single photons associated with the operation of our cold $^{\mathrm{87}}$Rb quantum memory. An Ar buffer gas is required to differentiate between signal and noise photons or similar statement. Our simple, passive filter requires no optical pumping or external frequency references and provides an additional 18 dB attenuation of our pump laser for every 1 dB loss of the single photon signal. We observe improved non-classical correlations and our data shows that the addition of a frequency filter increases the non-classical correlations and readout efficiency of our quantum memory by $\approx $ 35{\%}. [Preview Abstract] |
Friday, June 12, 2015 11:30AM - 11:42AM |
U7.00006: Generating Low-Frequency Squeezed Light from Four-Wave Mixing Meng-Chang Wu, Travis Horrom, Brian Anderson, Paul Lett We generate squeezed light near the D1 atomic resonance using four-wave mixing (4WM) in a warm Rb vapor. Given the desire in many applications to have squeezed light for measurement improvements at low (typically acoustic) frequencies, we are investigating what operating parameters affect the low-frequency squeezing in this system. We use an amplified, feedback-narrowed ($\sim$ 10 kHz linewidth) diode laser to pump and seed the process and we examine the effects of laser linewidth as well as the detuning, beam alignment and intensity parameters used in the generation process on the low frequency limit of the squeezing. Squeezing limits below 500 Hz are obtained. [Preview Abstract] |
Friday, June 12, 2015 11:42AM - 11:54AM |
U7.00007: The effect of off-resonant excitation on intensity-intensity correlation spectra in three-level, lambda systems Christopher DiLoreto, Chitra Rangan Developing methods for the detection of single molecules interacting with the environment has been a large area of research. These methods are quite varied in their execution and include antigen binding, surface plasmon resonance and fluorescence among many others. These methods all take advantage of the fact that molecular processes often change how a substrate interacts with light when a certain molecule is bound to it. With this in mind, we investigate if energy level changes of a fluorescent molecule due to ambient interactions can be detected by monitoring the two-time intensity-intensity correlation spectrum of the molecule when driven by electromagnetic waves. As these correlations depend on the severity of the off-resonance driving excitation, if the two-time intensity-intensity correlation spectrum were to be continuously monitored for a target transition in a three-level system, any changes that occur in the correlation spectrum could used to determine if the energy levels have changed and if any interactions have taken place. [Preview Abstract] |
Friday, June 12, 2015 11:54AM - 12:06PM |
U7.00008: Controlled rephasing of single spin-waves in a quantum memory based on cold atoms Pau Farrera, Boris Albrecht, Georg Heinze, Matteo Cristiani, Hugues de Riedmatten Quantum memories for light allow a reversible transfer of quantum information between photons and long lived matter quantum bits. In atomic ensembles, this information is commonly stored in the form of single collective spin excitations (spin-waves). In this work we demonstrate that we can actively control the dephasing of the spin-waves created in a quantum memory based on a cold Rb87 atomic ensemble. The control is provided by an external magnetic field gradient, which induces an inhomogeneous broadening of the atomic hyperfine levels. We show that acting on this gradient allows to control the dephasing of individual spin-waves and to induce later a rephasing. The spin-waves are then mapped into single photons, and we demonstrate experimentally that the active rephasing preserves the sub-Poissonian statistics of the retrieved photons. Finally we show that this rephasing control enables the creation and storage of multiple spin-waves in different temporal modes, which can be selectively readout. This is an important step towards the implementation of a functional temporally multiplexed quantum memory for quantum repeaters. [Preview Abstract] |
Friday, June 12, 2015 12:06PM - 12:18PM |
U7.00009: Control of Raman transitions between magnetic sublevels using circularly polarized light Svetlana Malinovskaya We study magnetic properties of ultracold alkali atoms trapped in a magneto-optical trap or in the optical lattice. The basis set is made of multiple magnetic sublevels existing within the hyperfne states of $^{87}Rb$. To perform quantum operations on the magnetic sublevels, we make use of crafted optical pulses and pulse trains with various polarizations. We will discuss a possibility to control selective excitation from and to specific magnetic sublevels by circularly polarized light and its combination with the constant magnetic field. [Preview Abstract] |
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