Bulletin of the American Physical Society
43rd Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 57, Number 5
Monday–Friday, June 4–8, 2012; Orange County, California
Session N6: Quantum Networks and Hybrid Quantum Systems |
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Chair: Luming Duan, University of Michigan - Ann Arbor Room: Garden 4 |
Thursday, June 7, 2012 10:30AM - 10:42AM |
N6.00001: An Elementary Quantum Network of Single Atoms in Optical Cavities Andreas Reiserer, Stephan Ritter, Christian Noelleke, Carolin Hahn, Andreas Neuzner, Manuel Uphoff, Martin Muecke, Eden Figueroa, Joerg Bochmann, Gerhard Rempe A quantum network consists of stationary nodes that are connected by quantum channels. Besides fundamental interest, such a quantum network is a prerequisite for distributed quantum computing architectures and has numerous applications in quantum communication. Here we present a prototype of such a quantum network based on two single atoms that are trapped in remote optical cavities and connected by an optical fiber link. The atom-cavity systems form universal quantum nodes in the sense that they are capable of sending, receiving, processing, storing and releasing quantum information that is encoded in the polarization of single photons. Via the temporal control of a coherent dark state we demonstrate the faithful transfer of a quantum state from one atom to the other. This is accomplished in the conceptually most fundamental way: by the coherent emission and absorption of a single photon. In the same way, we create a maximally entangled state between the two nodes that are in independent laboratories and separated by 20m. Due to its high efficiency and high fidelity ($\sim $0.9) our cavity-based approach paves the way towards large-scale quantum networks and their applications. [Preview Abstract] |
Thursday, June 7, 2012 10:42AM - 10:54AM |
N6.00002: Heralded entanglement of two remote atoms Michael Krug, Julian Hofmann, Norbert Ortegel, Lea Gerard, Kai Redeker, Florian Henkel, Wenjamin Rosenfeld, Markus Weber, Harald Weinfurter Entanglement between atomic quantum memories at remote locations will be a key resource for future applications in quantum communication. One possibility to generate such entanglement over large distances is entanglement swapping starting from two quantum memories each entangled with a photon. The photons can be transported to a Bell-state measurement where after the atomic quantum memories are projected onto an entangled state. We have set up two independently operated single atom experiments separated by 20 m. Via a spontaneous decay process each quantum memory, in our case a single Rb-87 atom, emits a single photon whose polarization is entangled with the atomic spin. The photons one emitted from each atom are collected into single-mode optical fibers guided to a non-polarizing 50-50 beam-splitter and detected by avalanche photodetectors. Bunching of indistinguishable photons allows to perform a Bell-state measurement on the photons. Conditioned on the registration of particular two-photon coincidences the spin states of both atoms are measured. The observed correlations clearly prove the entanglement of the two atoms. This is a first step towards creating a basic node of a quantum network as well as a key prerequisite for a future loophole-free test of Bell's inequality. [Preview Abstract] |
Thursday, June 7, 2012 10:54AM - 11:06AM |
N6.00003: Spectral control of spin qubits in diamond photonic structures Victor Acosta, Charles Santori, Andrei Faraon, Zhihong Huang, Raymond Beausoleil Integrated photonic networks based on cavity-coupled spin impurities offer a promising platform for scalable quantum computing. A key ingredient for this technology involves heralding entanglement by interfering indistinguishable photons emitted by pairs of identical spin qubits. The nitrogen-vacancy (NV) center in diamond is an attractive candidate for such a spin-photon interface, as it exhibits long-lived electronic spin coherence, rapid spin manipulation and readout, and the coexistence of both robust cycling and spin-altering Lambda-type transitions. We discuss current research in our lab to control the spectral properties of single NV centers by dynamic Stark tuning [1] and cavity Purcell enhancement [2]. In particular, we report progress on fabricating photonic structures in ultra-pure diamond, where NV centers are likely to have favorable optical properties. \\[4pt] [1] V. M. Acosta et al., Dynamic stabilization of the optical resonances of single nitrogen-vacancy centers in diamond, \underline {arXiv:1112.5490v1} [quant-ph]. \\[0pt] [2] A. Faraon et al., Coupling of nitrogen-vacancy centers to photonic crystal cavities in monocrystalline diamond, Submitted. [Preview Abstract] |
Thursday, June 7, 2012 11:06AM - 11:18AM |
N6.00004: Ultrafast Quantum Processing at Room-Temperature in Bulk Diamond Phonons Benjamin Sussman, Philip Bustard, K.C. Lee, Michael Sprague, Joshua Nunn, Nathan Langford, X.-M. Jin, Ian Walmsley, Doug Moffatt, Rune Lausten The two-level system comprised of the acoustic phonon and optical phonon of bulk diamond provides a unique opportunity for quantum processing at room-temperature with ultrafast rates. We present several applications including the generation of macroscopic non-classical states, a quantum memory for storing broad-band photons, and the generation of true random numbers from vacuum fluctuations. [Preview Abstract] |
Thursday, June 7, 2012 11:18AM - 11:30AM |
N6.00005: Entangled Optical Phonons in Diamond at Room Temperature Michael R. Sprague, Ka Chung Lee, Benjamin J. Sussman, Joshua Nunn, Nathan K. Langford, Xian-Min Jin, Tessa Champion, Patrick Michelberger, Klaus F. Reim, Duncan G. England, Dieter Jaksch, Ian A. Walmsley Diamond's many superlative features include a Raman-active optical phonon that is well-isolated from thermal fluctuations at room temperature. We enlist this mode to demonstrate entanglement between two macroscopic, spatially separated diamonds at room temperature with ultrashort pulses and a far-off-resonance Raman interaction. We measured the concurrence of the joint state of the Raman-scattered photons to determine that the optical phonon modes in the two diamonds were entangled. Our results demonstrate that entanglement can persist in the vibrational motion of macroscopic solids at room temperature. [Preview Abstract] |
Thursday, June 7, 2012 11:30AM - 11:42AM |
N6.00006: Spectroscopy of composite solid-state spin environments in diamond Nir Bar-Gill, My Linh Pham, Chinmay Belthangady, David Le Sage, Mikhail Lukin, Amir Yacoby, Paola Cappellaro, Ronald Walsworth We apply dynamical decoupling pulse sequences to nitrogen-vacancy centers in diamond in order to spectrally decompose the dynamics of their spin environment, which consists of nuclear and electronic spin impurities. We study a variety of diamond samples to identify the dynamics of the different spin baths and the interplay between them. These results are useful for the basic understanding of spin dynamics in solid-state systems and the central spin problem and could inform efforts in engineering optimized samples for collective quantum information processing and quantum metrology. [Preview Abstract] |
Thursday, June 7, 2012 11:42AM - 11:54AM |
N6.00007: Coupling ultra-cold atoms with nano-mechanics Andrew Geraci, Matt Eardley, Cris Montoya, John Kitching Recently there has been a significant interplay between the fields of solid-state and atomic physics, ranging from using ultra-cold atoms to simulate condensed-matter systems to physically coupling cold atoms with solid state devices such as micro-resonators. In particular, micro-mechanical resonators can be used to manipulate and probe cold atomic samples with single-spin sensitivity and sub-micron spatial resolution. We describe ongoing experimental efforts to couple laser-cooled Rb atoms to a magnetic cantilever tip, and discuss prospects for using nano-resonators for individual lattice-site addressing of atoms trapped in optical lattices [1]. Looking forward, hybrid quantum systems consisting of cold atoms interfaced with mechanical devices may have applications in quantum information science.\\[4pt] [1] A. A. Geraci and J. Kitching, Phys. Rev. A 80, 032317 (2009). [Preview Abstract] |
Thursday, June 7, 2012 11:54AM - 12:06PM |
N6.00008: Quantum interface between an electrical circuit and a single atom David Kielpinski, D. Kafri, M.J. Woolley, G.J. Milburn, J.M. Taylor We show how to bridge the divide between atomic systems and electronic devices by engineering a coupling between the motion of a single ion and the quantised electric field of a resonant circuit. The coupling uses parametric modulation of the circuit capacitance by a MEMS device to bridge the gap in timescales between the ion motion and circuit frequency. Our method can be used to couple the internal state of an ion to the quantised circuit with the same speed as the internal-state coupling between two ions. The parametric driving of the coupling adds negligible decoherence to the system. All the well-known quantum information protocols linking ion internal and motional states can be converted to protocols between circuit photons and ion internal states. Our results enable quantum interfaces between solid state qubits, atomic qubits, and light, and lay the groundwork for a direct quantum connection between electrical and atomic metrology standards. [Preview Abstract] |
Thursday, June 7, 2012 12:06PM - 12:18PM |
N6.00009: Atomic excitation with propagating light pulse and quantum memory with a half cavity Yimin Wang, Ji\v{r}\'{I} Min\'{a}\v{r}, Valerio Scarani, Gabriel H\'{e}tet State mapping between atoms and photons and photon-photon interactions play an key role in scalable quantum information processing. First, we consider the interaction of a single atom with a quantized light pulse propagating in free space. We show the dependence of the atomic excitation on (i) the quantum state of the pulse and (ii) the overlap between the pulse waveform and the atomic dipole pattern. We present a detailed study for both n-photon Fock state and coherent state pulses with various temporal shapes. The work is extended to the dynamics of two spatial modes propagating from opposite directions to the atom. Second, we propose a setup for quantum memory based on a single two-level atom in a half cavity with a moving mirror. We show that various temporal shapes of incident photon can be efficiently stored and readout by shaping the time-dependent decay rate $\gamma(t)$ describing the interaction between the atom and the light. We present an analytical expression for the efficiency of the storage and study its dependence on the ratio between the incident light field bandwidth and the atomic decay rate. We discuss possible implementations and experimental issues, particularly for a single atom or ion in a half cavity as well as a superconducting qubit in the circuit QED. [Preview Abstract] |
Thursday, June 7, 2012 12:18PM - 12:30PM |
N6.00010: Strongly interacting quantum excitations of a cold atomic gas Yaroslav Dudin, Alex Kuzmich Strong interactions of Rydberg atoms in a mesoscopic ensemble can be employed for fast preparation of desired many-particle states. In this work, Rydberg excitations are generated in an ultra-cold atomic Rb gas and are converted into light. As the principal quantum number n is increased beyond $\sim $ 70, no more than a single excitation is retrieved from a mesoscopic ensemble. These results hold promise for studies of dynamics and disorder in many-body systems with tunable interactions and for scalable quantum information networks. [Preview Abstract] |
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