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Closed-loop optimization of fast trapped-ion shuttling with sub-quanta excitation

npj Quantum Information

Sterk, Jonathan D.; Coakley, Henry J.; Goldberg, Joshua D.; Hietala, Vincent &.; Lechtenberg, Jason L.; McGuinness, Hayden J.; McMurtrey, Daniel L.; Parazzoli, Lambert P.; Van Der Wall, Jay W.; Stick, Daniel L.

Shuttling ions at high speed and with low motional excitation is essential for realizing fast and high-fidelity algorithms in many trapped-ion-based quantum computing architectures. Achieving such performance is challenging due to the sensitivity of an ion to electric fields and the unknown and imperfect environmental and control variables that create them. Here we implement a closed-loop optimization of the voltage waveforms that control the trajectory and axial frequency of an ion during transport in order to minimize the final motional excitation. The resulting waveforms realize fast round-trip transport of a trapped ion across multiple electrodes at speeds of 0.5 electrodes per microsecond (35 m∙s-1 for a one-way transport of 210 μm in 6 s) with a maximum of 0.36 ± 0.08 mean quanta gain. This sub-quanta gain is independent of the phase of the secular motion at the distal location, obviating the need for an electric field impulse or time delay to eliminate the coherent motion.

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Entangling-gate error from coherently displaced motional modes of trapped ions

Physical Review A

Ruzic, Brandon R.; Barrick, Todd A.; Hunker, Jeffrey D.; Law, Ryan L.; McFarland, Brian M.; McGuinness, Hayden J.; Parazzoli, L.P.; Sterk, Jonathan D.; Van Der Wall, Jay W.; Stick, Daniel L.

Entangling gates in trapped-ion quantum computers are most often applied to stationary ions with initial motional distributions that are thermal and close to the ground state, while those demonstrations that involve transport generally use sympathetic cooling to reinitialize the motional state prior to applying a gate. Future systems with more ions, however, will face greater nonthermal excitation due to increased amounts of ion transport and exacerbated by longer operational times and variations over the trap array. In addition, pregate sympathetic cooling may be limited due to time costs and laser access constraints. In this paper, we analyze the impact of such coherent motional excitation on entangling-gate error by performing simulations of Mølmer-Sørenson (MS) gates on a pair of trapped-ion qubits with both thermal and coherent excitation present in a shared motional mode at the start of the gate. Here, we quantify how a small amount of coherent displacement erodes gate performance in the presence of experimental noise, and we demonstrate that adjusting the relative phase between the initial coherent displacement and the displacement induced by the gate or using Walsh modulation can suppress this error. We then use experimental data from transported ions to analyze the impact of coherent displacement on MS-gate error under realistic conditions.

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Engineering the Quantum Scientific Computing Open User Testbed

IEEE Transactions on Quantum Engineering

Clark, Susan M.; Lobser, Daniel L.; Revelle, Melissa R.; Yale, Christopher G.; Bossert, David B.; Burch, Ashlyn D.; Chow, Matthew N.; Hogle, Craig W.; Ivory, Megan K.; Pehr, Jessica; Salzbrenner, Bradley S.; Stick, Daniel L.; Sweatt, W.C.; Wilson, Joshua M.; Winrow, Edward G.; Maunz, Peter

The Quantum Scientific Computing Open User Testbed (QSCOUT) at Sandia National Laboratories is a trapped-ion qubit system designed to evaluate the potential of near-term quantum hardware in scientific computing applications for the U.S. Department of Energy and its Advanced Scientific Computing Research program. Similar to commercially available platforms, it offers quantum hardware that researchers can use to perform quantum algorithms, investigate noise properties unique to quantum systems, and test novel ideas that will be useful for larger and more powerful systems in the future. However, unlike most other quantum computing testbeds, the QSCOUT allows both quantum circuit and low-level pulse control access to study new modes of programming and optimization. The purpose of this article is to provide users and the general community with details of the QSCOUT hardware and its interface, enabling them to take maximum advantage of its capabilities.

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TICTOC: Compact Atomic Clock with Integrated Photonics

Ivory, Megan K.; Ivory, Megan K.; Gehl, M.; Gehl, M.; Setzer, William J.; Setzer, William J.; McGuinness, Hayden J.; McGuinness, Hayden J.; Haltli, Raymond A.; Haltli, Raymond A.; Blain, Matthew G.; Blain, Matthew G.; Stick, Daniel L.; Stick, Daniel L.; Parazzoli, Lambert P.; Parazzoli, Lambert P.

Atomic clocks are precision timekeeping devices that form the basis for modern communication and navigation. While many atomic clocks are room-sized systems requiring bulky free space optics and detectors, the Trapped-lon Clock using Technology-On-Chip (TICTOC) project integrates these components into Sandia's existing surface trap technology via waveguides for beam delivery and avalanche photodiodes for light detection. Taking advantage of a multi-ensemble clock interrogation approach, we expect to achieve record time stability (< 1 ns error per year) in a compact (< /1 2 L) clock. Here, we present progress on the development of the integrated devices and recent trapped ion demonstrations.

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Micro-fabricated ion traps for Quantum Information Processing; Highlights and lessons learned

Maunz, Peter L.; Blume-Kohout, Robin J.; Blain, Matthew G.; Benito, Francisco B.; Berry, Christopher W.; Clark, Craig R.; Clark, Susan M.; Colombo, Anthony P.; Dagel, Amber L.; Fortier, Kevin M.; Haltli, Raymond A.; Heller, Edwin J.; Lobser, Daniel L.; Mizrahi, Jonathan M.; Nielsen, Erik N.; Resnick, Paul J.; Rembetski, John F.; Rudinger, Kenneth M.; Scrymgeour, David S.; Sterk, Jonathan D.; Tabakov, Boyan T.; Tigges, Chris P.; Van Der Wall, Jay W.; Stick, Daniel L.

Abstract not provided.

Assembling a Ring-Shaped Crystal in a Microfabricated Surface Ion Trap

Physical Review Applied

Tabakov, Boyan; Benito, Francisco; Blain, Matthew; Clark, Craig R.; Clark, Susan; Haltli, Raymond A.; Maunz, Peter; Sterk, Jonathan D.; Tigges, Chris; Stick, Daniel L.

We report on experiments with a microfabricated surface trap designed for confining a chain of ions in a ring. Uniform ion separation over most of the ring is achieved with a rotationally symmetric design and by measuring and suppressing undesired electric fields. After reducing stray fields, the ions are confined primarily by a radio-frequency pseudopotential and their mutual Coulomb repulsion. Approximately 400 Ca40+ ions with an average separation of 9 μm comprise the ion crystal.

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Micro-fabricated ion traps for Quantum Information Processing

Maunz, Peter L.; Hollowell, Andrew E.; Lobser, Daniel L.; Nordquist, Christopher N.; Benito, Francisco M.; Clark, Craig R.; Clark, Susan M.; Colombo, Anthony P.; Fortier, Kevin M.; Haltli, Raymond A.; Heller, Edwin J.; Resnick, Paul J.; Rembetski, John F.; Sterk, Jonathan D.; Stick, Daniel L.; Tabakov, Boyan T.; Tigges, Chris P.; Van Der Wall, Jay W.; Dagel, Amber L.; Blain, Matthew G.; Scrymgeour, David S.

Abstract not provided.

Frequency Translation to Demonstrate a Hybrid Quantum Architecture: Final Report

Clark, Susan M.; Fortier, Kevin M.; El-Kady, I.; McGuinness, Hayden J.; Stick, Daniel L.; Reinke, Charles M.

The Frequency Translation to Demonstrate a Hybrid Quantum Architecture project focused on developing nonlinear optics to couple two different ion species and make their emitted UV photons indistinguishable. Successful demonstration of photonic coupling of different ion species lays the foundation for coupling drastically different types of qubits, such as ions and quantum dots. Frequency conversion of single photons emitted from single ions remains a "hot" topic with many groups pursing this effort; however due to challenges in producing short period periodically poled crystal it has yet to be realized. This report details the efforts of trying to frequency convert single photons emitted from trapped ions to other wavelengths. We present our theoretical studies of candidate platforms for frequency conversion: photonic crystal fibers, X(2) nonlinear crystals in optical cavities, and photonic crystal cavities. We also present experiment results in ion trapping X(2) nonlinear crystals measurements and photonic crystal fabrication

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Precision alignment of integrated optics in surface electrode ion traps for quantum information processing

Proceedings of SPIE - The International Society for Optical Engineering

Young, Amber L.; Hunker, Jeffrey D.; Ellis, A.R.; Samora, S.; Wendt, J.R.; Stick, Daniel L.

The integration of optics for efficient light delivery and the collection of fluorescence from trapped ions in surface electrode ion traps is a key component to achieving scalability for quantum information processing. Diffractive optical elements (DOEs) present a promising approach as compared to bulk optics because of their small physical profile and their flexibility in tailoring the optical wavefront. The precise alignment of the optics for coupling fluorescence to and from the ions, however, poses a particular challenge. Excitation and manipulation of the ions requires a high degree of optical access, significantly restricting the area available for mounting components. The ion traps, DOEs, and other components are compact, constraining the manipulation of various elements. For efficient fluorescence collection from the ions the DOE must be have a large numerical aperture (NA), which results in greater sensitivity to misalignment. The ion traps are sensitive devices, a mechanical approach to alignment such as contacting the trap and using precision motors to back-off a set distance not only cannot achieve the desired alignment precision, but risks damage to the ion trap. We have developed a non-contact precision optical alignment technique. We use line foci produced by off-axis linear Fresnel zone plates (FZPs) projected on alignment targets etched in the top metal layer of the ion trap and demonstrate micron-level alignment accuracy. © 2014 SPIE.

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Sandia Micro-fabricated Ion Traps for the MUSIQC architecture

Maunz, Peter L.; Heller, Edwin J.; Hollowell, Andrew E.; Kemme, S.A.; Loviza, Becky G.; Mizrahi, Jonathan A.; Ortega, Anathea C.; Scrymgeour, David S.; Sterk, Jonathan D.; Tigges, Chris P.; Dagel, Amber L.; Clark, Craig R.; Stick, Daniel L.; Blain, Matthew G.; Clark, Susan M.; Resnick, Paul J.; Arrington, Christian L.; Benito, Francisco M.; Boye, Robert B.; Ellis, A.R.; Haltli, Raymond A.

Abstract not provided.

Microfabricated surface ion traps for quantum computation

Highstrete, Clark H.; Stick, Daniel L.; Tigges, Chris P.; Blain, Matthew G.; Fortier, Kevin M.; Haltli, Raymond A.; Kemme, S.A.; Lindgren, Thomas L.; Moehring, David L.

We will present results of the design, operation, and performance of surface ion micro-traps fabricated at Sandia. Recent progress in the testing of the micro-traps will be highlighted, including successful motional control of ions and the validation of simulations with experiments.

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Demonstrating Robustness of Analogue Quantum Simulators (AQS)

Clark, Susan M.; Hogle, Craig W.; Young, Kevin C.; Stick, Daniel L.

In this report we describe the construction and characterization of a small quantum processor based on trapped ions. This processor could ultimately be used to perform analogue quantum simulations with an engineered computationally-cold bath for increasing the system's robustness to noise. We outline the requirements to build such a simulator, including individual addressing, distinguishable detection, and low crosstalk between operations, and our methods to implement and characterize these requirements. Specifically for measuring crosstalk, we introduce a new method, simultaneous gate set tomography to characterize crosstalk errors.

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75 Results
75 Results