Bulletin of the American Physical Society
2013 Joint Meeting of the APS Division of Atomic, Molecular & Optical Physics and the CAP Division of Atomic, Molecular & Optical Physics, Canada
Volume 58, Number 6
Monday–Friday, June 3–7, 2013; Quebec City, Canada
Session C5: Trapped Ion Technology |
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Chair: Chenglin Cao, University of Maryland Room: 301 |
Tuesday, June 4, 2013 2:00PM - 2:12PM |
C5.00001: Fast, High Fidelity State Detection of a $^{171}$Yb$^{+}$ Ion Using Large Numerical Aperture Optics Rachel Noek, Geert Vrijsen, Daniel Gaultney, Emily Mount, So-Young Baek, Peter Maunz, Jungsang Kim Trapped ions provide a viable choice for quantum bits (qubits) for quantum information as most of the DiVincenzo criteria have been demonstrated [1]. However, some scalability challenges remain including the qubit measurement speed, which is typically much slower than gate times, and remote entanglement generation rate, which is currently much slower than qubit coherence times. Current photon collection rates limit the overall speed and fidelity of the qubit detection in a trapped ion quantum processor. Recent advances have been made in improving the state detection fidelity, but the detection time remains long ($\sim$ ms) compared to typical gate operations ($\sim$10$^{1}$-10$^{2}$ us). Here, we use a high numerical aperture (NA$=$0.6) lens capable of collecting 10{\%} of the solid angle of light emitted by a single ion to measure a detection fidelity of 99.7{\%} (99.85{\%}) with an integration time of 50 us (150 us). Advanced discrimination schemes can further improve the state detection speed. The $^{171}$Yb$^{+}$ ion is trapped in a Thunderbird type surface trap designed and fabricated at Sandia National Laboratories. \\[4pt] [1] D. J. Wineland, et al., J. Res. Natl. Inst. Stand. Technol. 103, 259 (1998). [Preview Abstract] |
Tuesday, June 4, 2013 2:12PM - 2:24PM |
C5.00002: New technology for quantum control of multi-species ion chains Ben Keitch I will present recent results of the trapping and control of calcium ions in a microfabricated, segmented Paul trap. The trap is a four-layer design that includes segmented compensation electrodes and that is optimized for implementing quantum control, separation and shuttling of mixed-species ion strings. The key features of the experimental apparatus include: \\[4pt] $\,\bullet$ Two high NA imaging systems, consisting of a custom in-vacuum objective for simultaneous diffraction-limited imaging at 313nm and 397nm. \\ $\,\bullet$ A $>$1W 313nm laser system for high-fidelity gate operations.\\ $\,\bullet$ A custom-built FPGA-based control system that uses an embedded processor controlling many distributed programmable DDS systems in a scalable architecture.\\[4pt] I will explain how these new technological elements will enable us to explore mixed-species gates, and perform open system quantum simulations by using one ion species as an artificial environment for the other. [Preview Abstract] |
Tuesday, June 4, 2013 2:24PM - 2:36PM |
C5.00003: Scalable Trapped Ion Quantum Computing using Multiple Ion Species John Wright, Richard Graham, Tomasz Sakrejda, Zichao Zhou, Boris Blinov We are investigating the use of co-trapped Ytterbium and Barium ions to build a scalable quantum computer. The ground state hyperfine levels of Ytterbium-171 will be used as qubits, while Barium-138 will be used to sympathetically cool the system. Further, Ba-138 will be used to extend quantum operations over multiple traps (possibly in separate physical vacuum chambers) by performing photon-mediated remote ion-ion entanglement. The 493 nm transition of Ba$+$ allows the use of low attenuation fibers and fiber beamsplitters for this procedure. Operations within the Yb$+$ hyperfine manifold, as well as local interspecies entanglement, will be generated by stimulated Raman transitions driven by the second (532 nm) and third (355 nm) harmonics of a modelocked 1064nm YAG laser for Ba$+$ and Yb$+$, respectively. We report progress towards realizing this system in a standard Paul trap, as well as an analogous system in a microfabricated chip trap, where separate ion chains can be operated on simultaneously. [Preview Abstract] |
Tuesday, June 4, 2013 2:36PM - 2:48PM |
C5.00004: Surface ion trap structures with excellent optical access for quantum information processing P. Maunz, M. Blain, F. Benito, C. Chou, C. Clark, M. Descour, R. Ellis, R. Haltli, E. Heller, S. Kemme, J. Sterk, B. Tabakov, C. Tigges, D. Stick Microfabricated surface electrode ion traps are necessary for the advancement of trapped ion quantum information processing as it offers a scalable way for realizing complex trap structures capable of storing and controlling many ions. The most promising way of performing two-qubit quantum gates in a chain of trapped ions is to focus laser beams on individual ions of the chain to drive gates. However, in surface ion traps the close proximity of the ions to the surface and the size of the chips usually cannot accommodate the tightly focused laser beams necessary to address individual ions parallel to the chip surface. Here we present a surface electrode ion trap monolithically fabricated in standard silicon technology that implements a linear quadrupole trap on a bowtie shaped chip with a narrow section that is only 1.2mm wide. Laser beams parallel to the surface can be focused down to a waist of 4$\mu $m with enough separation from the trap chip to prevent light scattering. The trap structure incorporates two Y-junctions for reordering ions and is optimized for quantum information processing. This work was supported by the Intelligence Advanced Research Projects Activity (IARPA). Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the US Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000. [Preview Abstract] |
Tuesday, June 4, 2013 2:48PM - 3:00PM |
C5.00005: Robust quantum control of $^{171}$Yb$^+$ qubits in a surface-trap with integrated microwave elements J. True Merrill, Christopher M. Shappert, Kenton R. Brown, Curtis Volin, Harley Hayden, C.-S. Pai, Alexa W. Harter We present a microfabricated surface-electrode ion trap with a pair of on-chip microwave waveguides for coherent operations on hyperfine $^{171}$Yb$^+$ qubits. Our design uses common silicon-on-aluminum microfabrication techniques compatible with integration in other surface-trap designs. We demonstrate sub-microsecond $\pi$-times, microwave polarization control, and coherence lifetimes exceeding $T_2 > 0.1$ s. We also demonstrate coherent transport of qubits over a 1.8 mm distance. Further, we utilize compensating composite pulses which reduce sensitivity to field variations to produce extremely uniform gates over a 0.9 mm qubit manipulation region. [Preview Abstract] |
Tuesday, June 4, 2013 3:00PM - 3:12PM |
C5.00006: A System for Trapping Barium Ions in a Microfabricated Surface Trap Zichao Zhou, John Wright, Richard Graham, Tomasz Sakrejda, Bing Chen, Boris Blinov We have developed a vacuum chamber and control system for rapid testing and development of microfabricated surface traps. Barium ions have been successfully cooled and trapped in this system. The dark lifetime of a single 138Ba$+$ in this trap is up to 30s. And we can shuttle of ions at rate of 8 cm/s between different potential zones. Our system uses a modular design and is based on an in-vacuum PCB with integrated filters. Control of up to 96 DC electrodes is achieved with an update rate of 20 kHz using a custom FPGA based control system. Collection of fluorescence light over a numerical aperture of 0.28 has been achieved. [Preview Abstract] |
Tuesday, June 4, 2013 3:12PM - 3:24PM |
C5.00007: Stability of Ion Chains in a Cryogenic Surface-Electrode Ion Trap Grahame Vittorini, S. Charles Doret, Kenneth R. Brown, Alexa W. Harter Cryogenic environments offer significant advantages for ion trapping due to their potential for low trap heating rates and exceptional vacuum. This makes cooled ion traps well suited to the study of chains of ions, which ordinarily suffer from melting and short lifetimes in conventional room temperature ion trapping systems. We have developed a simple, modular cryostat for use with surface-electrode ion traps that provides flexible optical access, high numerical aperture imaging, and excellent vacuum. Using this system we are investigating the stability of and ion loss from small chains of ions as a function of local factors such as vacuum quality, laser cooling parameters, and modifications to trapping potentials. [Preview Abstract] |
Tuesday, June 4, 2013 3:24PM - 3:36PM |
C5.00008: Fast ion shuttling methods for segmented ion traps Ludwig de Clercq, Joseba Alonso, Matteo Fadel, Karin Fisher, Ben Keitch, Daniel Kienzler, Florian Leupold, Frieder Lindenfelser, Hsiang-Yu Lo, Vlad Negnevitsky, Jonathan Home I will present a new scheme for fast diabatic control of ion trap potentials, based on the use of in-vacuum high-speed switched electronics [1]. We have investigated theoretically the use of this method for transport within a single oscillation cycle of the ion in the trap, and for producing squeezed vacuum states. I will describe the cryogenic apparatus we are developing for investigating these possibilities using a micro-fabricated surface-electrode trap. In a second approach to ion transport using analog waveforms, I will describe the use of Tikhonov regularization to calculate voltage sequences required for shuttling chains containing Ca$^{+}$ and Be$^{+}$ ions in a segmented linear Paul trap. \\[4pt] [1] Alonso et al. arxiv:quant-ph/1208.3986, to be published in New Journal of Physics (2013) [Preview Abstract] |
Tuesday, June 4, 2013 3:36PM - 3:48PM |
C5.00009: Coupled Resonance Laser Frequency Stabilization Shaun Burd, Hermann Uys We have demonstrated simultaneous laser frequency stabilization of a UV and IR laser, to the same photodiode signal derived from the UV laser only. For trapping and cooling Yb$^+$ ions, a frequency stabilized laser is required at 369.9nm to drive the S$_{1/2}$-P$_{1/2}$ cooling cycle. Since that cycle is not closed, a repump beam is needed at 935.18nm to drive the D$_{3/2}$-D$_{[3/2]}$ transition, which rapidly decays back to the S$_{1/2}$ state. Our 369nm laser is locked using Doppler free polarization spectroscopy of Yb$^+$ ions, generated in a hollow cathode discharge lamp. Without pumping, the metastable D$_{3/2}$ level is only sparsely populated, making direct absorption of 935nm light difficult to detect. A resonant 369nm pump laser can populate the D$_{3/2}$ state, and fast repumping to the S$_{1/2}$ ground state by on resonant 935nm light, can be detected via the change in absorption of the 369nm laser. This is accomplished using lock-in detection on the same photodiode signal to which the 369nm laser is locked. In this way, simultaneous locking of two frequencies in very different spectral regimes is accomplished, while exploiting only the photodiode signal from one of the lasers. A rate equation model gives good qualitative agreement with experimental observation. [Preview Abstract] |
Tuesday, June 4, 2013 3:48PM - 4:00PM |
C5.00010: Sideband cooling for improved sympathetic heating spectroscopy James Goeders, Charles Nichols, Kenneth Brown Sympathetic Heating Spectroscopy (SHS), in which the laser-frequency dependent heating of an (spectroscopy) ion of interest is measured by observing the fluorescence of a second (control) ion as the system is re-cooled, may be used to detect weak spectral lines via atomic fluorescence. Low photon scattering rates from the spectroscopy ion can still create a significant stochastic optical force, Doppler shifting the resonance of the control ion in a way which can be observed during recooling. Previous work in our lab has demonstrated observable signals from scattering rates as low as 1500 photons/s. To observe transitions with still lower scattering rates, such as those present in molecular ions, the sensitivity of SHS must be improved. One method is to sideband cool the Coulomb crystal to the ground state and observe heating by measuring the relative heights of the first order secular motion sidebands. As a first step, sideband cooling of both ions must be demonstrated. This talk will discuss progress towards this goal of sympathetic ground state cooling. [Preview Abstract] |
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