1,993 research outputs found

    Strong interactions of single atoms and photons in cavity QED

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    An important development in modern physics is the emerging capability for investigations of dynamical processes for open quantum systems in a regime of strong coupling for which individual quanta play a decisive role. Of particular significance in this context is research in cavity quantum electrodynamics which explores quantum dynamical processes for individual atoms strongly coupled to the electromagnetic field of a resonator. An overview of the research activities in the Quantum Optics Group at Caltech is presented with an emphasis on strong coupling in cavity QED which enables exploration of a new regime of nonlinear optics with single atoms and photons

    Comment on "Deterministic Single-Photon Source for Distributed Quantum Networking" by Kuhn, Hennrich, and Rempe

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    I comment on the experiment to realize an "on-demand," reversible single-photon source by Kuhn, Hennrich, and Rempe [Phys. Rev. Lett. 89, 067901 (2002)].Comment: 2 pages, 1 figur

    Near-Field Emission of Lead-Sulfide-Selenide Homojunction Lasers

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    Measurements of the near-field intensity distributions of three lead-sulfide-selenide diode lasers operating near 4.8 μm have been made as a function of injection current. Localized emission in the near field exhibits peaked structure of full width from 5 to 10 μm for operation above threshold. From the dependence of the emission profiles on injection current estimates of 25 cm ^(-1) and 0.09 cm/A are made for the distributed loss and gain coefficients for one of the lasers. Optical confinement perpendicular to the p-n junction can be explained in terms of the homojunction properties

    Atom galleries for whispering atoms: binding atoms in stable orbits around an optical resonator

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    The external fields of optical whispering gallery modes may be used to confine atoms in stable orbits around a dielectric microsphere. As an example, a toroidal dipole-force trap (atom gallery) for three-level atoms is investigated, and the possibility of achieving an atomic (matter-wave) resonator is discussed. The extremely small electromagnetic mode volumes and high Q's of the whispering gallery modes should permit a circulating photon to be repeatedly absorbed and reemitted by a trapped whispering atom

    Observation of a single atom in a magneto-optical trap

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    Fluorescence from Cs atoms in a magneto-optical trap is detected under conditions of very low atomic density. Discrete steps are observed in the fluorescent signal versus time and are associated with the arrival and departure of individual trapped atoms. Histograms of the frequency of occurrence of a given level of fluorescence exhibit a series of uniformly spaced peaks that are attributed to the presence of N = 0, 1, 2 atoms in the trap

    Quantum structure and dynamics for atom galleries

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    The bound state structure and dynamics for an atom trap formed from the whispering gallery modes (WGMs) of a dielectric microsphere are investigated. The coupling of the quantized internal and external atomic degrees of freedom plays a fundamental role in the quantum dynamics of this atom gallery. The radiative processes for a cold atom near a microsphere are modified due to the special symmetry of the atom gallery, the WGM mode structure, and the finite extent of the center-of-mass (c.m.) wave packet. Finally, interesting implications of the quantized c.m. for atomic matter waves and cavity QED with a quantum field are mentioned

    Teleportation of continuous quantum variables

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    Quantum teleportation is analyzed for states of dynamical variables with continuous spectra, in contrast to previous work with discrete (spin) variables. The entanglement fidelity of the scheme is computed, including the roles of finite quantum correlation and nonideal detection efficiency. A protocol is presented for teleporting the wave function of a single mode of the electromagnetic field with high fidelity using squeezed-state entanglement and current experimental capability

    Well-dressed states for wave-packet dynamics in cavity QED

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    The quantization of atomic center-of-mass motion is considered within the context of cavity QED with particular emphasis on the dynamics of localized wave packets. “Well-dressed” states are introduced as an eigenbasis that incorporates both the quantized atom-field interaction and the external bound states of a potential well. The interplay of internal and external time scales generates qualitatively new dynamics such as novel “collapses” and “revivals.

    Efficient Quantum Computation with Probabilistic Quantum Gates

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    With a combination of the quantum repeater and the cluster state approaches, we show that efficient quantum computation can be constructed even if all the entangling quantum gates only succeed with an arbitrarily small probability p. The required computational overhead scales efficiently both with 1/p and n, where n is the number of qubits in the computation. This approach provides an efficient way to combat noise in a class of quantum computation implementation schemes, where the dominant noise leads to probabilistic signaled errors with an error probability 1-p far beyond any threshold requirement

    Quantum Optics with Atomic Ensembles and Single Atoms in Cavities

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    Current experiments in our group explore the quantum interface between matter and light, with the goal of achieving coherent control for implementing quantum information protocols and quantum networks. We outline recent progress in this direction, including localization to the ground state of motion for an atom trapped in an optical cavity, observation of strong coupling between single Cesium atoms and a monolithic resonator, and generation and characterization of entanglement stored in remote atomic ensembles
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