Bulletin of the American Physical Society
40th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 54, Number 7
Tuesday–Saturday, May 19–23, 2009; Charlottesville, Virginia
Session J1: Quantum Interferometry and Spin Squeezing |
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Chair: Juha Javanainen, University of Connecticut Room: Chemistry Building 402 |
Thursday, May 21, 2009 8:00AM - 8:12AM |
J1.00001: State Preparation for Rare-Earth Ion Based Quantum Memory Elizabeth Goldschmidt, Sarah Beavan, Matthew Eisaman, Jingyun Fan, Michael Hohensee, Zachary Levine, Ludwig Mathey, Sergey Polyakov, Alan Migdall We report progress in using spectral hole-burning in praseodymium doped yttrium orthosilicate to prepare an ensemble of Pr ions with a spectral distribution optimized for use in a Duan-Lukin-Cirac-Zoller-type (DLCZ) quantum-repeater scheme. We are studying the feasibility of this spectral hole-burning scheme for the DLCZ protocol and computationally optimizing parameters including the Rabi frequencies of the hole-burning fields and the pulsing parameters. We are experimentally studying the time required to reach steady state for each of the steps of the hole-burning sequence and find that this time differs for the various steps when all other parameters are kept the same. We discuss our computational and experimental progress toward implementing this state preparation scheme and our plans for further work. [Preview Abstract] |
Thursday, May 21, 2009 8:12AM - 8:24AM |
J1.00002: Practical quantum metrology with Bose-Einstein condensates Alexandre Tacla, Sergio Boixo, Animesh Datta, Matthew Davis, Anil Shaji, Carlton Caves We analyze in detail the recently proposed experiment [Boixo et al., Phys. Rev. Lett. {\bf 101}, 040403 (2008)] for achieving better than $1/n$ scaling in a quantum metrology protocol using a two mode Bose-Einstein condensate of $n$ atoms. There were several simplifying assumptions in the original proposal that made it easy to see how a scaling approaching $1/n^{3/2}$ may be obtained. We look at these assumptions in detail to see when they may be justified. We present numerical results that confirm our theoretical predictions for the effect of the spreading of the BEC wave function with increasing $n$ on the scaling. Numerical integration of the coupled Gross-Pitaevskii equations for the two mode BEC also shows that the assumption that the two modes share the same spatial wave function is justified for a length of time that is sufficient to run the metrology scheme. [Preview Abstract] |
Thursday, May 21, 2009 8:24AM - 8:36AM |
J1.00003: A Simple Criterion for Quantum States of Light to Be Applicable for the Heisenberg-Limited Interferometry Hwang Lee, Yang Gao Based on quantum information theory we present a criterion for quantum states of light to determine whether a certain input state can be used to achieve the Heisenberg limit. It provides a necessary condition for the Heisenberg-limited optical interferometry. This criterion can be expressed by the distance, between the input and output states, should depend linearly on the change of the phase difference in the limit of vanishing phase difference. On the other hand, since it does not rely on, nor specify what detection scheme to be adopted, the detection scheme needs be constructed independently. We also show that it is consistent with the previously known result suggested by Ou, based on a quantum nondemolition measurement scheme. [Preview Abstract] |
Thursday, May 21, 2009 8:36AM - 8:48AM |
J1.00004: Quantum Eraser for Improved Spin Squeezing in a Double-Pass Optical-Feedback Geometry Collin Trail, Ivan Deutsch Squeezed collective atomic spin states can be generated using the Faraday effect, by passing light through an atomic sample twice, imprinting the spin component along the direction of the propagation of light on to the light on the first pass, and rotating the atoms proportionally to this spin component on the second pass, thus creating an effective nonlinearity (M. Takeuchi et al., 2005, Phys. Rev. Lett. 94, 023003). The squeezing produced is reduced by loss of light still entangled to the atoms. We show how this scheme can be improved by a quantum eraser effect, where measuring the light properly reduces it's entanglement to our atomic sample. Grant NSF 0653599 [Preview Abstract] |
Thursday, May 21, 2009 8:48AM - 9:00AM |
J1.00005: Optimization of States in a Lossy Interferometer Blane McCracken, Tae-Woo Lee, Sean D. Huver, Lev Kaplan, Hwang Lee, Changjun Min, Dmitry B. Uskov, Christoph F. Wildfeuer, Georgios Veronis, Jonathan P. Dowling We have utilized a genetic algorithm to determine the minimum possible phase sensitivity in a lossy interferometer, and the corresponding quantum states that yield this optimization. The setup involves an arbitrary source with a finite number of photons which is sent through the two lossy arms of the interferometer. The detection process passes the two arms through a beam splitter and measures the output with number resolving detectors. The detection probability is used in calculating the Fisher information and minimum phase sensitivity of the interferometer. The optimization parameters consisted of relative phase shift between the arms of the interferometer in addition to input state amplitude and phase coefficients. We found that maintaining no loss in the control arm of the interferometer increases phase sensitivity for all values of loss in the target arm. Although no single state is optimally phase sensitive over the entire regime of loss, the optimum sensitivity as a function of loss for any number of photons has a nearly identical exponential dependence in the high loss regime. [Preview Abstract] |
Thursday, May 21, 2009 9:00AM - 9:12AM |
J1.00006: Interferometry with a photon-number resolving detector Christoph Wildfeuer, Aaron Pearlman, Jun Chen, Jingyun Fan, Alan Migdall, Jonathan Dowling In this contribution, we present our studies of Michelson and Fabry-Perot interferometers with a photon-number resolving detector. We show experimentally that with a weak coherent light beam, the use of a photon-number resolving detector leads to a compression of the interference fringes. We also discuss how to improve the sensitivity of interferometers below the shot-noise limit by using nonclassical light and photon-number resolving detectors. [Preview Abstract] |
Thursday, May 21, 2009 9:12AM - 9:24AM |
J1.00007: Optimized Double-Well Quantum Interferometry with Gaussian Squeezed States Yuping Huang, Michael Moore Previous Hiesenberg-limited interferometry schemes using NOON, Twin-Fock and similar states perform worse than shot-noise when measuring a nonzero phase. We have found that a Mach-Zehnder interferometer with a Gaussian number-difference squeezed input state can exhibit sub-shot-noise phase resolution over a large phase interval, accomplished by optimizing the level of squeezing based on the phase interval $\Delta \theta_0$ and particle number $N$ [1]. This can be combined with an adaptive measurement sequence in which the amount of squeezing is increased with each measurement, with the result that any phase on $(-\Delta\theta_0, \Delta\theta_0)$ can be measured with a precision of $3.5/N$, requiring only 2-4 measurements, provided only that $N \tan(\Delta\theta_0)<10^ {40}$. In a double-well Bose-Einstein condensate, the optimized input states can be created by adiabatic manipulation of the interaction to tunneling ratio, and is robust against imprecise control of squeezing and inaccurate knowledge of $N$. [1] Y. P. Huang and M. G. Moore, Phys. Rev. Lett. 100, 250406 (2008). [Preview Abstract] |
Thursday, May 21, 2009 9:24AM - 9:36AM |
J1.00008: Quantum transport in a nonlinear optical fiber: single-photon switching, photonic bound states and more Mohammad Hafezi, Darrick E. Chang, Vladimir Lukin, Eugene Demler, Mikhail D. Lukin We examine the quantum transport properties of a few photons inside a one-dimensional nonlinear waveguide when the evolution is determined by the quantum nonlinear Schrodinger equation. The tight transverse confinement of the photonic modes enables a large atom-field coupling strength. Therefore, by coupling light to atoms loaded in a fiber, such a system is capable of acting as a single-photon switch, where the transmission of single photons occurs with high probability while that of multiple photons is strongly suppressed. This switching behavior also manifests itself in higher-order correlation functions of the transmitted field. In particular, when the interaction between photons is effectively repulsive, the suppression of multi-photon components results in anti-bunching of the transmitted field. In the attractive case, the switch can exhibit both anti-bunching and bunching behaviors. We show that the bunching is due to the resonant excitation of bound states of photons by the input field. Finally, an experimental implementation of such a system in hollow-core fibers loaded with cold atoms is discussed. [Preview Abstract] |
Thursday, May 21, 2009 9:36AM - 9:48AM |
J1.00009: Decoherence-enhanced measurements Daniel Braun, John Martin The idea of quantum-enhanced measurements (QEM) is to use quantum-engineered states, such as squeezed light, as probes of classical system properties, such as the length of an optical cavity. These methods promise to beat the standard quantum limit (SQL), in which the uncertainty of the measured quantity scales as the inverse square root of the number of quantum constituents N of the probe (such as the number of photons), and to potentially achieve the Heisenberg limit, where the scaling is 1/N. However, experimental progress has been slow, as the highly non-classical quantum states required are in general very prone to decoherence. In this talk we show that decoherence itself can be exploited to reach the Heisenberg limit, without the need to produce highly entangled states. We will discuss this new method of ``Decoherence-enhanced measurements'' in detail for the example of the measurement of the length of an optical cavity. [Preview Abstract] |
Thursday, May 21, 2009 9:48AM - 10:00AM |
J1.00010: Parity detection in Quantum Optical metrology Aravind Chiruvelli, Hwang Lee We show the utility of parity detection to achieve Heisenberg-limited phase estimation for optical interferometry. We consider the parity detection with several input states that have been shown to exhibit sub shot-noise interferometry with their respective detection schemes. We show that with parity detection, all these states achieve the sub-shot noise limited phase estimate. Thus making the parity detection a unified detection strategy for quantum optical metrology. [Preview Abstract] |
Thursday, May 21, 2009 10:00AM - 10:12AM |
J1.00011: Two-photon absorption of path-entangled number states Petr Anisimov, William N. Plick, Christoph F. Wildfeuer, Hwang Lee, Jonathan P. Dowling In this contribution, we present our studies of two-photon absorption of path-entangled number states $\vert $M,M+2$>+\vert $M+2,M$>$. We show theoretically that these states with detection scheme based on a two-photon absorber are super-resolving and provide high absorption rate with a visibility of 20{\%} in the limit of large M. We also discuss sensitivity of a two-photon absorber based detection scheme of above mentioned states and show that the phase sensitivity suffers significant reduction. [Preview Abstract] |
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