Bulletin of the American Physical Society
51st Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 65, Number 4
Monday–Friday, June 1–5, 2020; Portland, Oregon
Session T03: New Techniques in Ion TrappingLive
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Chair: Paul Hess, Middlebury Room: D135-136 |
Friday, June 5, 2020 10:30AM - 10:42AM Live |
T03.00001: Buffer gas cooling of a trapped ion to the quantum regime Michal Tomza, Thomas Feldker, Henning Furst, Henrik Hirzler, Norman Ewald, Matteo Mazzanti, Dariusz Wiater, Rene Gerritsma Significant advances in precision measurements in the quantum regime have been achieved with trapped ions and atomic gases at the lowest possible temperatures. These successes have inspired ideas to merge the two systems [1]. In this way, one can study the unique properties of ionic impurities inside a quantum fluid. Remarkably, in spite of its importance, experiments with ion-atom mixtures remained firmly confined to the classical collision regime. Here, we report buffer gas cooling of a single ion in a Paul trap to the quantum regime of ion-atom collisions [2]. We have achieved collision energy as small as 1.15(0.23) times the $s$-wave energy (or 9.9(2.0) $\mu$K) for a trapped ytterbium ion in an ultracold lithium gas. We have observed a deviation from classical Langevin theory by studying the spin-exchange dynamics, indicating quantum effects in the ion-atom collisions. By developing a theoretical model of measured energy-dependent spin-exchange rate constants, we have obtained singlet and triplet ion-atom scattering lengths. Our results open up numerous opportunities, such as the exploration of ion-atom Feshbach resonances, in analogy to neutral systems. [1] Tomza et al, Rev. Mod. Phys. 91, 035001 (2019) [2] Feldker et al, Nature Physics, doi:10.1038/s41567-019-0772-5 (2020) [Preview Abstract] |
Friday, June 5, 2020 10:42AM - 10:54AM Live |
T03.00002: Double-EIT Ground-State Cooling of Stationary Two-Dimensional Ion Lattices Mu Qiao, Ye Wang, Zhengyang Cai, Botao Du, Pengfei Wang, Chunyang Luan, Wentao Chen, Kihwan Kim We theoretically and experimentally study the electromagnetically-induced-transparency (EIT) cooling of two-dimensional ion lattices in a Paul trap. We realize the EIT ground-state cooling with $^{171}\mathrm{Yb}^+~$ ions with hyperfine-energy levels different from other ions with a simple $\Lambda$-scheme that has already been used. We observe a cooling rate $\dot{\bar n}=3\times 10^4$quanta/s and a cooling limit $\bar n=0.06\pm 0.059$ for a single ion. The measured cooling rate and limit are consistent with theoretical predictions. We apply the double-EIT cooling on two-dimensional (2D) lattices with up to 12 ions and observe an average phonon number $\bar n =0.54\pm 0.12$ for the center of mass mode. Different from the 2D crystal in the Penning trap, cooling rates of multiple ions are similar to that of a single ion. The ground-state cooling of a 2D lattice with a large number of $^{171}\mathrm{Yb}^+~$ ions will advance the field of the quantum simulation of 2D systems. Our method can be also extended to the other hyperfine qubits. [Preview Abstract] |
Friday, June 5, 2020 10:54AM - 11:06AM Live |
T03.00003: A Miniature Room Temperature Trapped Ion System Geert Vrijsen, Yuhi Aikyo, Tom Noel, Alex Kato, Jungsang Kim Trapped ion systems are among the leading platforms for practical quantum computers thanks to their long coherence times, high-fidelity gates, and potential for full connectivity of qubits. The main limitations on the gate fidelities of current state-of-the-art systems come from systematic control errors in the laser beam delivery, primarily due to mechanical and temperature instabilities. We are addressing these problems by designing and building a miniaturized ($3\,$cm$^3$ internal volume) ultra-high-vacuum (UHV) system with an integrated surface ion trap and $0.2\,$L/s ion pump. The final seal between the trap and vacuum lid is performed under UHV conditions, which enables processing capabilities such as argon-ion sputtering to clean trap electrodes in order to reduce anomalous heating effects. Neutral ytterbium (Yb) atoms are generated from a metallic sample by laser ablation with a pulsed Nd:YAG laser, are subsequently photo-ionized, and then trapped. The vacuum level was characterized by placing a single trapped ion in a double well potential and monitoring the collision-driven well-to-well hopping rate. Lastly, the ion re-ordering rate in a 6-ion chain was measured by including several ions of a different non-fluorescing Yb isotope. [Preview Abstract] |
Friday, June 5, 2020 11:06AM - 11:18AM Live |
T03.00004: Characterization of a Compact Cryogenic Package Approach to Ion Trapping Robert Spivey, Zhubing Jia, Ismail Inlek, Ke Sun, Stephen Crain, Rachel Noek, Kenneth Brown, Jungsang Kim We present a novel ion trapping environment where conventional ultra-high vacuum (UHV) chambers are replaced with a compact enclosure sealed to a ceramic package operating in a cryogenic environment. A microfabricated surface ion trap mounted on a modified ceramic pin grid array (CPGA) package is covered with a copper lid containing the vacuum environment. The small environment is differentially pumped via cryogenic pumping at 7K, where UHV pressures are reached. To load the ions, metallic ytterbium (Yb) is ablated using a Q-switched Nd:YAG laser at 532 nm. Heating rates of 90 quanta/s are measured in a Sandia HOA trap. Single qubit and two qubit M{\o}lmer--S{\o}rensen gates are demonstrated using a stable and compact Raman beam delivery system. We present an estimation of internal pressure calculated from zig-zag phase changes in ion chains. [Preview Abstract] |
Friday, June 5, 2020 11:18AM - 11:30AM Live |
T03.00005: Crystals of $^{\mathrm{40}}$Ca$^{\mathrm{+}}$ and $^{\mathrm{9}}$Be$^{\mathrm{+}}$ in a Compact Penning Trap Brian McMahon, Brian Sawyer Penning ion traps are useful experimental platforms for quantum simulation, mass spectrometry, precision metrology, molecular spectroscopy, and measurements of fundamental constants. We recently developed a compact, permanent-magnet based Penning trap that is compatible with cold ion physics experiments at 0.6 T [1]. We will describe the results of trap magnetic field characterization (both stability and uniformity) using confined, laser-cooled $^{\mathrm{40}}$Ca$^{\mathrm{+}}$ and $^{\mathrm{9}}$Be$^{\mathrm{+}}$ as probes. We have also demonstrated a laser cooling technique for $^{\mathrm{40}}$Ca$^{\mathrm{+}}$ at high magnetic field that allows for spin state detection without the need for shelving to metastable D levels. This cooling and detection scheme reduces the laser requirements for Penning trap experiments with atomic ions possessing low-lying D states. [1] B. J. McMahon, C. Volin, W. G. Rellergert, and B. C. Sawyer, Phys. Rev. A \textbf{101}, 013408 (2020) [Preview Abstract] |
Friday, June 5, 2020 11:30AM - 11:42AM Live |
T03.00006: Isotope selective ion trap loading with pulsed laser ablation of BaCl targets Brendan White, Pei Jiang Low, Matt Day, Usman Khan, Crystal Senko We present our efforts towards laser ablating Barium atoms from a salt compound and using photoionization to selectively load different ion isotopes. Commonly, ion trapping groups use a resistively heated oven as a source for atoms, a method which takes on the order of minutes and results in a high rate of contamination on trap electrodes. Pulsed laser ablation allows one to trap and turn off the loading mechanism instantaneously, allowing us to load a particular chain of ions much more quickly and displace less material. In addition, the heat load applied near the ion trap is much lower. We show that laser ablation can be applied to BaCl salt targets to produce and trap Barium ions. Further, we demonstrate that by controlling the frequency of the first photoionization laser, we can discriminate between the different isotopes of Barium; we can then selectively ionize a desired isotope for loading in our ion trap. [Preview Abstract] |
Friday, June 5, 2020 11:42AM - 11:54AM Live |
T03.00007: Progress towards optically trapping 2d ion crystals Matt Grau, Oliver Wipfli, Christoph Fischer, Jonathan Home Arrays of trapped ions and Rydberg atoms are both attractive platforms for quantum simulation due to high-level single particle of control and the presence of long-range interactions. However, current techniques for trapped ions are limited by micromotion and lattice geometry, while Rydberg atoms remain challenging to trap in attractive potentials. We are developing a new apparatus to trap arrays of ions in optical lattices, which combine the flexible geometry found in neutral atom experiments with the high degree of control and large interaction strengths found in ion experiments. Two-dimensional arrays of around 40 ions could be trapped with inter-ion distances of under 10 microns, and also with low residual heating rates due to off-resonant scattering and laser fluctuations. This will be made possible by using a deep lattice potential formed by the large optical intensity in a high-finesse optical cavity. In a complementary effort, the polarizability of the alkali-like ion core of an alkaline earth atom could be used to trap neutral atoms excited to Rydberg states. Sufficiently high angular momentum Rydberg states should suppress loss of atoms from the trap by autoionization. Experimental progress towards these goals will be described. [Preview Abstract] |
Friday, June 5, 2020 11:54AM - 12:06PM Live |
T03.00008: Multi-zone parallel qubit addressing via multi-wavelength integrated photonics Robert Niffenegger, Jules Stuart, Colin Bruzewicz, David Reens, Cheryl Sorace-Agaskar, Dave Kharas, Jeremy Sage, John Chiaverini The integration of photonics within surface-electrode ion-trap chips could enable the development of larger quantum computers and portable quantum sensors. Here, we demonstrate operation of an ion-trap chip where integrated waveguides and grating couplers deliver all required wavelengths, from the violet to the infrared, necessary to control Sr$^{+}$ qubits. Using these integrated photonics, we demonstrate photoionization of neutral Sr, Doppler cooling, electronic-state repumping, sideband cooling, coherent qubit operations, and qubit-state preparation and detection. Laser light is coupled onto the chip via an optical-fiber array, creating an inherently stable optical path that we use to demonstrate qubit coherence resilient to platform vibrations approaching 1g. We also explore using multiple zones of interaction to perform parallel qubit operations on multiple ions using multiple integrated beam paths. [Preview Abstract] |
Friday, June 5, 2020 12:06PM - 12:18PM Live |
T03.00009: Multi-tone RF generation for trapped-ion control with low-latency feedback Martin Stadler, Vlad Negnevitsky, Utku Altunkaya, Maciej Malinowski, Karan Mehta, Chi Zhang, Thanh-Long Nguyen, Cagri Oenal, Jonathan Home The complexity of classical control systems for trapped-ion experiments is increasing steadily with the need for more complex control of laser pulse shapes and fast-feedback for quantum error correction as well as classical feedback control. I will give an overview of our in-house developed control system which is capable of performing integrated feedback to stabilize laser pulse intensities during a pulse sequence. We are currently implementing a second generation using one GS/s arbitrary waveform generator driven by multiple independent DDS cores per channel. This allows the use of multiple frequency tones per channel, which we have used to cancel spurious frequency components coming from higher-order effects in AOMs when driven with two tones e.g. for a Mølmer-Sørensen gate. Additional features include pulse area stabilization with 1 micro-second feedback latency. I will put the use of this system into the context of recent experiments working with micro-fabricated ion traps. [Preview Abstract] |
Friday, June 5, 2020 12:18PM - 12:30PM Not Participating |
T03.00010: Progress Towards Integrated Photonic Waveguides for UV Light F. W. Knollmann, D. Kharas, C. Sorace-Agaskar, G. West, J. M. Sage, J. Chiaverini, D. Leibfried, A. C. Wilson, D. H. Slichter Microfabricated photonic waveguides and chip-integrated light delivery holds promise for a variety of atomic physics applications, including quantum computing and portable atomic clocks. For trapped ion applications, integrated photonics can potentially ease scaling to large numbers of trapping zones and improve beam pointing stability and vibration insensitivity. Recent results have demonstrated integrated photonic delivery of all wavelengths necessary to control a single Sr+ ion, from 1092 nm to 405 nm [1]. However, many trapped ions have transitions in the UV at wavelengths below 400 nm, where integrated photonic waveguides can exhibit high losses. Previous work has tested microfabricated waveguide losses down to wavelengths of 371 nm [2]. We report progress on characterizing similar waveguides deeper in the UV, at 313 nm and 280 nm, wavelengths relevant for Be+ and Mg+ ions. [1] R. J. Niffenegger et al., arXiv 2001.05052 (2020) [2] G. N. West et al., APL Photonics 4, 026101 (2019) [Preview Abstract] |
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