Bulletin of the American Physical Society
47th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 61, Number 8
Monday–Friday, May 23–27, 2016; Providence, Rhode Island
Session H4: Quantum Networks and Protocols |
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Chair: Paul Hess, Joint Quantum Institute, University of Maryland-College Park Room: 554AB |
Wednesday, May 25, 2016 10:30AM - 10:42AM |
H4.00001: A single ion coupled to a UV fiber-cavity Hendrik-Marten Meyer, Timothy Ballance, Ashwin Boddeti, Pascal Kobel, Kilian Kluge, Jakob Reichel, Michael K\"ohl Trapped ions offer long trapping and coherence times, which is why they are of great interest for the use as stationary qubits in a quantum network. Here we investigate the integration of fiber based cavities into ion traps, which due to their small mode volume and direct coupling to a single mode fiber present an efficient interface between single ions and single photons. In the past, ions and fiber-cavities have been successfully combined in the infra-red spectral range. Since ions typically have their strongest dipole transition in the ultra-violet (UV), the extension of fiber cavities to work in the UV is necessary. We will present our latest results on trapping Ytterbium ions inside approximately 150 micro-meter long fiber-cavities, which are resonant with the S-P electric dipole transition at 370nm. [Preview Abstract] |
Wednesday, May 25, 2016 10:42AM - 10:54AM |
H4.00002: Cross-species gates in a Ba/Yb ion trap for modular networked quantum computing Martin Lichtman, Ismail Inlek, Clay Crocker, Ksenia Sosnova, Chris Monroe A modular network of many ion traps is a promising approach to building a scalable quantum computer. Generation of entanglement between remote atomic qubits has been demonstrated using interference of simultaneously emitted photons from one qubit in each trap. However, stray photons emitted during this process may corrupt information stored in nearby qubits. To avoid this problem we have implemented co-trapping of two different elements in the same ion trap. $^{171}$Yb$^+$ is used as a quantum memory and processor, while $^{138}$Ba$^+$ is used for communication. The 493 nm photons from Ba$^+$ do not couple to the Yb$^+$ system, and suffer less attenuation in fiber optics than wavelengths available from most commonly trapped ion species. In this talk we report demonstration of state mapping between the Yb$^+$ and Ba$^+$ internal qubits, and progress towards utilizing these techniques in entanglement of remote qubits. [Preview Abstract] |
Wednesday, May 25, 2016 10:54AM - 11:06AM |
H4.00003: Barium Qubit State Detection and Ba Ion-Photon Entanglement Ksenia Sosnova, Ismail Volkan Inlek, Clayton Crocker, Martin Lichtman, Christopher Monroe A modular ion-trap network is a promising framework for scalable quantum-computational devices. In this architecture, different ion-trap modules are connected via photonic buses while within one module ions interact locally via phonons. To eliminate cross-talk between photonic-link qubits and memory qubits, we use different atomic species for quantum information storage ($^{171}$Yb$^+$) and intermodular communication ($^{138}$Ba$^+$). Conventional deterministic Zeeman-qubit state detection schemes require additional stabilized narrow-linewidth lasers. Instead, we perform fast probabilistic state detection utilizing efficient detectors and high-NA lenses to detect emitted photons from circularly polarized 493 nm laser excitation. Our method is not susceptible to intensity and frequency noise, and we show single-shot detection efficiency of $\sim$2\%, meaning that we can discriminate between the two qubits states with 99\% confidence after as little as 50 ms of averaging. Using this measurement technique, we report entanglement between a single $^{138}$Ba$^+$ ion and its emitted photon with 86\% fidelity. [Preview Abstract] |
Wednesday, May 25, 2016 11:06AM - 11:18AM |
H4.00004: Quantum teleportation from light beams to vibrational states of a macroscopic diamond. Panyu Hou, Yuanyuan Huang, Xinxing Yuan, Xiuying Chang, Chong Zu, Li He, Luming Duan Quantum teleportation is an unusual disembodied form of quantum information transfer through pre-shared entanglement and classical communication, which has found important applications for realization of various quantum technologies. It is of both fundamental interest and practical importance to push quantum teleportation towards macroscopic objects. With the recent development of optomechanics, the vibration in solids, involving collective motion of trillions of atoms, gradually enters into the realm of quantum control. Built on the recent remarkable progress in optical control of motional states in diamond, we report an experimental demonstration of quantum teleportation from light beams to vibrational states of a macroscopic diamond under ambient conditions. Through quantum state tomography, we demonstrate an average teleportation fidelity (90.6\pm 1.0){\%}, exceeding the classical limit of 2/3. The experiment pushes the target of quantum teleportation to the biggest object so far, with interesting implications for quantum foundational studies, optomechanical quantum control and quantum information science. [Preview Abstract] |
Wednesday, May 25, 2016 11:18AM - 11:30AM |
H4.00005: Experimental demonstration of a quantum router Xinxing Yuan, JIajun Ma, Panyu Hou, Xiuying Chang, Chong Zu, Luming Duan The router is a key element for a network. We describe a scheme to realize genuine quantum routing of single-photon pulses based on cascading of conditional quantum gates in a Mach-Zehnder interferometer and report a proof-of-principle experiment for its demonstration using linear optics quantum gates. The polarization of the control photon routes in a coherent way the path of the signal photon while preserving the qubit state of the signal photon represented by its polarization. We demonstrate quantum nature of this router by showing entanglement generated between the initially unentangled control and signal photons, and confirm that the qubit state of the signal photon is well preserved by the router through quantum process tomography. [Preview Abstract] |
Wednesday, May 25, 2016 11:30AM - 11:42AM |
H4.00006: Quantum repeater with continuous variable encoding Linshu Li, Victor V. Albert, Marios Michael, Sreraman Muralidharan, Changling Zou, Liang Jiang Quantum communication enables faithful quantum state transfer between different parties and protocols for cryptographic purposes. However, quantum communication over long distances (\textgreater 1000km) remains challenging due to optical channel attenuation. This calls for investigation on developing novel encoding schemes that correct photon loss errors efficiently. In this talk, we introduce the generalization of multi-component Schr\"{o}dinger cat states [1] and propose to encode quantum information in these cat states for ultrafast quantum repeaters [2,3]. We detail the quantum error correction procedures at each repeater station and characterize the performance of this novel encoding scheme given practical imperfections, such as coupling loss. A comparison with other quantum error correcting codes for bosonic modes will be discussed. [1] M. Mirrahimi, Z. Leghtas, V. V. Albert, S. Touzard, R. J. Schoelkopf, L. Jiang, and M. H. Devoret, New J. Phys. 16, 045014 (2014). [2] S. Muralidharan, J. Kim, N. L\"{u}tkenhaus, M. D. Lukin, and L. Jiang, Phys. Rev. Lett. 112, 250501 (2014). [3] S. Muralidharan, L. Li, J. Kim, N. L\"{u}tkenhaus, M. D. Lukin, and L. Jiang, arXiv:1509.08435 [Preview Abstract] |
Wednesday, May 25, 2016 11:42AM - 11:54AM |
H4.00007: Proposal for a telecom quantum repeater with single atoms in optical cavities Manuel Uphoff, Manuel Brekenfeld, Dominik Niemietz, Stephan Ritter, Gerhard Rempe Quantum repeaters hold the promise to enable long-distance quantum communication via entanglement generation over arbitrary distances. Single atoms in optical cavities have been shown to be ideally suited for the experimental realization of many tasks in quantum communication. To utilize these systems for a quantum repeater, it would be desirable to operate them at telecom wavelengths. We propose to use a cascaded scheme employing transitions at telecom wavelengths between excited states of alkali atoms for entanglement generation between a single photon at telecom wavelength and a single atom at the crossing point of two cavity modes. A cavity-assisted quantum gate can be used for entanglement swapping. We estimate the performance of these systems using numerical simulations based on experimental parameters obtained for CO$_2$ laser-machined fiber cavities in our laboratory. Finally, we show that a quantum repeater employing the aforementioned scheme and current technology could outperform corresponding schemes based on direct transmission. [Preview Abstract] |
Wednesday, May 25, 2016 11:54AM - 12:06PM |
H4.00008: A controllable single photon beam-splitter as a node of a quantum network. Santosh Kumar, Gaurav Gautam, Saikat Ghosh, Deepak Kumar A theoretical model for a controlled single-photon beam-splitter is proposed and analysed. It consists of two crossed optical-cavities with overlapping waists, dynamically coupled to a single flying atom. The system is shown to route a single photon with near-unity efficiency in an effective ``weak-coupling'' regime. Furthermore, two such nodes, forming a segment of a quantum network, are shown to perform several controlled quantum operations. All one-qubit operations involve a transfer of a photon from one cavity to another in a single node, while two-qubit operations involve transfer from one node to a next one, coupled via an optical fiber. Novel timing protocols for classical optical fields are found to simplify possible experimental realizations along with achievable effective parameter regime. This model can be extended to various other physical systems including gated quantum dots, circuit-QED or opto-mechanical elements. [Preview Abstract] |
Wednesday, May 25, 2016 12:06PM - 12:18PM |
H4.00009: Saving entangled photons from sudden death is a single-mode fiber ---- Interplay of Decoherence and dynamical decoupling. Manish Kumar Gupta, Chenglong You, Jonathan P. Dowling, Hwang Lee We study the dynamics of decoherence in an optical fiber for the case of entangled photons. Such a study will allow us to increase the physical length of fiber for transmission of entangled photon from the sources such as SPDC. We analytically derive the model for Decoherence of entangled state photons in a single-mode fiber. We also show that entanglement lifetime can be increased for Bell state and Werner state with open loop control technique called Dynamical decoupling. [Preview Abstract] |
Wednesday, May 25, 2016 12:18PM - 12:30PM |
H4.00010: Unconditional polarization qubit quantum memory at room temperature Mehdi Namazi, Connor Kupchak, Bertus Jordaan, Reihaneh Shahrokhshahi, Eden Figueroa The creation of global quantum key distribution and quantum communication networks requires multiple operational quantum memories. Achieving a considerable reduction in experimental and cost overhead in these implementations is thus a major challenge. Here we present a polarization qubit quantum memory fully-operational at 330K, an unheard frontier in the development of useful qubit quantum technology. This result is achieved through extensive study of how optical response of cold atomic medium is transformed by the motion of atoms at room temperature leading to an optimal characterization of room temperature quantum light-matter interfaces. Our quantum memory shows an average fidelity of 86.6 $\pm$ 0.6{\%} for optical pulses containing on average 1 photon per pulse, thereby defeating any classical strategy exploiting the non-unitary character of the memory efficiency. Our system significantly decreases the technological overhead required to achieve quantum memory operation and will serve as a building block for scalable and technologically simpler many-memory quantum machines. [Preview Abstract] |
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