Bulletin of the American Physical Society
39th Annual Meeting of the APS Division of Atomic, Molecular, and Optical Physics
Volume 53, Number 7
Tuesday–Saturday, May 27–31, 2008; State College, Pennsylvania
Session U2: Focus Session: Strongly Correlated Photons |
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Chair: Matt Mackie, Temple University Room: Kern Building 112 |
Saturday, May 31, 2008 8:00AM - 8:36AM |
U2.00001: Strong Interactions of Photon Pairs in Cavity QED Invited Speaker: The charge and spin degrees of freedom of massive particles have relatively large long-range interactions, which enable nonlinear coupling between pairs of atoms, ions, electrons, and diverse quasi-particles. By contrast, photons have vanishingly small cross-sections for direct coupling. Instead, photon interactions must be mediated by a material system. Even then,typical materials produce photon-photon couplings that are orders of magnitude too small for nontrivial dynamics with individual photon pairs. The leading exception to this state of affairs is cavity quantum electrodynamics (cQED), where strong interactions between light and matter at the single-photon level have enabled a wide set of scientific advances [1]. My presentation will describe two experiments in the Caltech Quantum Optics Group where strong interactions of photon pairs have been observed. The work in Ref. [2] provided the initial realization of photon blockade for an atomic system by using a Fabry-Perot cavity containing one atom strongly coupled to the cavity field. The underlying blockade mechanism was the quantum anharmonicity of the ladder of energy levels for the composite atom-cavity system. Beyond this \textit{structural} effect, a new \textit{% dynamical} mechanism was identified in Ref. [3] for which photon transport is regulated by the conditional state of one intracavity atom, leading to an efficient mechanism that is insensitive to many experimental imperfections and which achieves high efficiency for single-photon transport. The experiment utilized the interaction of an atom with the fields of a microtoroidal resonator [4]. Regulation was achieved by way of an interference effect involving the directly transmitted optical field, the intracavity field in the absence of the atom, and the polarization field radiated by the atom, with the requisite nonlinearity provided by the quantum character of the emission from one atom.\smallskip \newline \newline [1] R. Miller, T. E. Northup, K. M. Birnbaum, A. Boca, A. D. Boozer, and H. J. Kimble, J. Phys. B: At. Mol. Opt. Phys. \textbf{38}, S551-S565 (2005). \newline [2] K. M. Birnbaum, A. Boca, R. Miller, A. D. Boozer, T. E. Northup, and H. J. Kimble, Nature \textbf{436}, 87 (2005). \newline [3] B. Dayan, A. S. Parkins, T. Aoki, H. J. Kimble, E. Ostby, and K. J. Vahala, Science (in press, 2008). \newline [4] Takao Aoki, B. Dayan, E. Wilcut, W. P. Bowen, A. S. Parkins, H. J. Kimble, T. J. Kippenberg, and K. J. Vahala, Nature \textbf{443}, 671 (2006). [Preview Abstract] |
Saturday, May 31, 2008 8:36AM - 8:48AM |
U2.00002: Coherent control of a single atom in cavity QED T.E. Northup, A.D. Boozer, R. Miller, A. Boca, D. Wilson, H.J. Kimble In order to construct cavity QED-based quantum networks, we require both the coherent manipulation of trapped intracavity atoms as well as the ability to map quantum states between the atom and the cavity field. We have demonstrated the reversible transfer of a coherent state of light to and from the hyperfine states of an atom trapped within the mode of a high-finesse optical cavity. \footnote{A. D. Boozer, A. Boca, R. Miller, T. E. Northup, and H. J. Kimble, Phys. Rev. Lett. 98, 193601 (2007).} Following preparation of an atom in a specific Zeeman state \footnote{ A. D. Boozer, R. Miller, T. E. Northup, A. Boca, and H. J. Kimble, Phys. Rev. A 76, 063401 (2007).}, we can also transfer population between hyperfine ground states via Raman transitions, where we make use of an efficient state detection scheme enabled by strong atom-cavity coupling. Here we discuss and quantify the decoherence mechanisms present in the system and present a mapping from a superposition of the atom's Zeeman states onto its hyperfine states, a prerequisite for detection of entanglement between atomic and photonic qubits. [Preview Abstract] |
Saturday, May 31, 2008 8:48AM - 9:00AM |
U2.00003: Combining Cavity QED and Atom Chips Thomas Purdy, Daniel Brooks, Dan Stamper-Kurn We have integrated the magnetic trapping technology of atom chips with high finesse optical cavities. Our high current capacity atom chip, consisting of a micromachined silicon substrate with thick, buried copper wires, can confine clouds of cold atoms to dimensions much less than an optical wavelength. Multiple Fabry-Perot optical resonators in the single-atom strong coupling regime of cavity QED are integrated with the chip in a configuration where the optical cavity modes form through micromachined holes which perforate the chip substrate. Because the atom chip affords precise control of the position of atoms within the standing-wave structure of the cavity mode, we will be able to study the coupling between optical and mechanical degrees of freedom of the atom-cavity system at the level where quantum effects play an important role. [Preview Abstract] |
Saturday, May 31, 2008 9:00AM - 9:12AM |
U2.00004: Progress Toward a Cavity-QED Realization of the Dicke Model Quantum Phase Transition Robert Cook, Ben Baragiola, JM Geremia We present progress towards a Cavity-QED realization of the quantum phase transition seen in the Dicke Model Hamiltonian for $N > 1$ spins coupled to a single Bosonic field mode, as proposed by Dimer \emph{et. al.} Phys. Rev. A. \textbf{75}, 013804 (2007). The implementation is based upon cesium atoms held within a high finesse optical cavity. Cavity-mediated Raman transitions between magnetically detuned Zeeman sublevels provides near critical coupling between a collective pseudo-spin and a quantized cavity mode. Progress has been made in building the necessary infrastructure to collect $\sim10^{6}$ atoms in an intracavity optical lattice, while still maintaining a background pressure of $\sim10^{-10}$ torr. A tandem vacuum chamber provides a pressure difference of 2 orders of magnitude. A 2D-MOT will funnel atoms from a high pressure chamber into the lower pressure science chamber. Current efforts are directed towards capturing the funneled atoms. [Preview Abstract] |
Saturday, May 31, 2008 9:12AM - 9:48AM |
U2.00005: Strongly correlated photons in one-dimensional waveguides Invited Speaker: One-dimensional waveguide naturally arises in nanophotonic systems. A line defect state in a photonic crystal with a complete band gap, for example, forms a true one-dimensional continuum of photons, since, within a certain frequency range, except for the guided modes, there are no other modes. To a great extent, all waveguides that are strongly confined, including high-index contrast dielectric nanowires, and plasmonic waveguides, can be well approximated as a one-dimensional system as well. Here we discuss a set of very unusual quantum optical effects, when a two-level atom is coupled to such a one-dimensional waveguide. We show that this system is described by a Hamiltonian that is an exact photonic analogue of the Anderson Hamiltonian in the infinite-U limit. Using this Hamiltonian, we show that a single photon injected into such a waveguide will be completely reflected on resonance by the two-level atom. In one-dimensional systems, therefore, one can use the spontaneous emission property of the atom, which was commonly thought of as a decoherence mechanism, to coherently control the transport properties of light. Moreover, we show that when two photons are incident, their transport properties become strongly correlated. We have developed a Bethe Ansatz technique to exactly solve for the transport properties of two photons in such a system. The theoretical predictions include the effects of single-photon switching, background fluorescence, as well as strong spatial attraction and repulsion of photons. [Preview Abstract] |
Saturday, May 31, 2008 9:48AM - 10:00AM |
U2.00006: Conditional Quantum Beats in Cavity QED David Norris, Rebecca Olson Knell, Jietai Jing, L.A. Orozco We study optical correlations in a cavity QED system, which supports two modes of orthogonal linear polarization, traversed by Rb atoms from a low velocity beam. The combination of the two modes with the magnetic structure of the atoms allows us to separate photons originating from spontaneous emission from those that come from the drive. Conditional measurement of the undriven mode intensity (intensity autocorrelation) reveals quantum beats at the Larmor frequency for an applied magnetic field. Detection of the first fluorescent photon prepares a superposition of two magnetic sublevels of the ground state that evolves dynamically until the next excitation event. The detection probability for a second fluorescent photon then exhibits a modulation with frequency proportional to the magnitude of the weak magnetic field (less than 10 G.) The appearance of these fringes depends upon the geometry of the applied magnetic field, the polarization of the drive, and the detuning of the cavity, providing several options for the implementation of quantum control. The transition to strong driving causes the oscillations to disappear. We explore the implications of this coherence for the realization of a quantum eraser in cavity QED. Work supported by NSF. [Preview Abstract] |
Saturday, May 31, 2008 10:00AM - 10:12AM |
U2.00007: Can we make precision measurements more precise? James K. Thompson, Shannon R. Sankar, Zilong Chen Precision measurements using atoms and molecules--including searches for permanent electric dipole moments, variation of the fine-structure constant with time, clocks, magnetometers, and inertial sensors--are fundamentally limited by the quantum projection noise in the read out of the atomic or molecular state. One approach to reducing this source of imprecision is to measure the quantum noise at the beginning of an experiment and then to simply subtract it out at the end of the experiment. If the optical depth of the atomic ensemble can be made large, phase shifts or polarization rotation of laser light can serve as the required non-destructive probe of the quantum noise present in the initial state of an atomic ensemble. This talk will present recent progress on using optical cavities to boost the effective optical depth of an atomic ensemble by 3 to 4 orders of magnitude with the goal of suppressing quantum projection noise by amounts of real interest to precision measurements. [Preview Abstract] |
Saturday, May 31, 2008 10:12AM - 10:24AM |
U2.00008: Spin squeezing in optical lattice clocks through lattice based quantum non-demolition measurements Dominic Meiser, Murray J. Holland Optical lattice clocks based on neutral earth alkaline atoms have made dramatic progress recently and are now competitive with the most stable frequency standards. In the current generation of experiments the short time stability of the clocks is within a factor of two of the spin projection noise limited stability. In this presentation we show that the atoms imprint information on the lattice beams that can be used to perform a quantum non-demolition measurement of the atomic state. Such a quantum non-demolition measurement can reduce the spin-projection noise below the standard quantum limit through measurement back-action induced spin squeezing thus enabling still better short time stability of the lattice clock. In addition to potentially leading to better clocks this work also opens up new areas of research at the interface of cavity QED, condensed matter physics and precision measurements. [Preview Abstract] |
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