Bulletin of the American Physical Society
53rd Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 67, Number 7
Monday–Friday, May 30–June 3 2022; Orlando, Florida
Session H09: Advances in Trapped Ion Quantum ComputingRecordings Available
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Chair: Crystal Senko, UWaterloo Room: Salon 11/12 |
Wednesday, June 1, 2022 8:00AM - 8:12AM |
H09.00001: Microwave-driven quantum logic in Ca43+ at 288 Gauss Marius Weber, Clemens Loschnauer, Jochen Wolf, Mario F Gely, Ryan K Hanley, Joseph F Goodwin, Thomas Harty, Andrew Steane, David M Lucas Magnetic field gradients, generated by microwave circuitry in the proximity of trapped ions, can couple the ions internal and motional degrees of freedom to implement two-qubit gates [1,2]. This approach presents many advantages with respect to laser-driven gates: the hardware is cheaper and more readily scalable, phase control is facilitated, and photon scattering errors are eliminated. |
Wednesday, June 1, 2022 8:12AM - 8:24AM |
H09.00002: A next-generation trapped ion quantum computing system Yichao Yu, Lei Feng, LIUDMILA ZHUKAS, Marko Cetina, Crystal Noel, Debopriyo Biswas, Andrew Risinger, Alexander Kozhanov, Christopher R Monroe The first generation of a universal trapped ion integrated quantum processor, constructed in a collaboration between universities and industrial partners, was used to perform quantum algorithms with high-fidelity on 12 qubits, and high-fidelity quantum gates with up to 23 qubits. We present progress on the second-generation system, which has several design improvements, such as a capacity of 32 qubits, parallel addressing capability using an RF-System-On-Chip, a next-generation micro-fabricated surface ion trap from Sandia National Laboratories, and the integration with the upgraded Raman and CW laser systems built by L3Harris. |
Wednesday, June 1, 2022 8:24AM - 8:36AM |
H09.00003: Comparison of Quantum Entangling Gates for Ions in Penning and RF Paul Traps Allison L Carter, Jennifer F Lilieholm, Bryce B Bullock, Matthew J Affolter, John J Bollinger Trapped ions have high gate fidelities making them a leading platform for quantum simulation and computation. Entangling gates are typically performed using a Mølmer-Sørensen or light-shift geometric phase gate. In our Penning trap, we have performed quantum simulations on crystals of hundreds of ions using the light-shift gate because of the difficulty of spanning our 124 GHz qubit splitting in 9Be+ at 4.5 T. One advantage of the Mølmer-Sørensen gate, however, is that it can be configured such that the motion of the ions is less sensitive to the optical phase difference between the driving laser beams. It can therefore be used to improve sensing applications and drive gates in 3-D crystals of up to 105 ions. |
Wednesday, June 1, 2022 8:36AM - 8:48AM |
H09.00004: Barium Ions for omg-style Trapped-Ion Quantum Information Susanna L Todaro, Xiaoyang Shi, Karen Lei, Kyle DeBry, Sam B Alterman, Felix W Knollmann, Gabriel Mintzer, Trevor McCourt, Jasmine Sinanan-Singh, Colin D Bruzewicz, John Chiaverini, Isaac L Chuang Most quantum information experiments with trapped ions encode the qubit either between two Zeeman or hyperfine sublevels of the ground electronic state or between the ground state and a long-lived metastable state. A third category is the metastable qubit, in which quantum information is encoded in sublevels of the metastable state. Qubits in this manifold would be largely insensitive to scattered laser light addressing a neighboring qubit in the ground state manifold, potentially enabling quasi-dual-species operation in a chain of identical ions. Barium-133 ions have accessible visible and infrared transition wavelengths, nuclear spin I = 1/2, and a metastable state with a 26 second lifetime, making them appealing for this application. However, this isotope is radioactive, with a 10.5-year half-life. Photo-ionization of neutral barium atoms produced by laser ablation of a barium compound could enable isotope-selective loading of a small volume source, improving the ease of working with radioactive material. We characterize the production of neutral and ionic barium by laser ablation from both BaCl2 and BaTiO3. We also discuss progress loading, cooling, and coherently controlling barium ions produced by such a method in a surface electrode trap. |
Wednesday, June 1, 2022 8:48AM - 9:00AM |
H09.00005: Zeeman metastable qubit operations in trapped 40Ca+ ions Kyle DeBry, Penny E Brant, Colin D Bruzewicz, David L Reens, May E Kim, Robert McConnell, Philip H Rich, Jules M Stuart, Susanna L Todaro, Isaac L Chuang, John Chiaverini Dual-species trapped ion experiments provide benefits such as sympathetic cooling and ancilla readout without unwanted crosstalk and decoherence from scattered resonant photons. However, the different masses and transition frequencies of unlike ions introduce new technical challenges such as trap anharmonicities and the need for additional lasers. By encoding qubits in sublevels (hyperfine or Zeeman) of both the ground state and a long-lived metastable state, we achieve the benefits of multi-species operation within ions of a single species. Here, we investigate a metastable qubit stored in Zeeman sublevels of the 3D5/2 state of 40Ca+ ions. Operations on a neighboring ground-state 40Ca+ qubit can then be performed with minimal crosstalk. Metastable qubit gates are performed with RF pulses that drive transitions between two sublevels of the metastable state. The energy splittings between the six Zeeman levels are equal, so a laser is used to shift other levels out of resonance with the RF pulses. We also describe progress towards sympathetic cooling with a co-trapped ground state ion, as well as the potential for using the full Hilbert space of both the ground and metastable levels for qudit algorithms. |
Wednesday, June 1, 2022 9:00AM - 9:12AM |
H09.00006: Quantum information protocols with metastable trapped-ion barium qubits Ana Sotirova, Fabian Pokorny, Jamie Leppard, Andres Vazquez Brennan, Chris J Ballance We can harness the rich internal structure of ions to enhance quantum information processing in trapped-ion devices by using unorthodox qubit states [1]. Barium is particularly well-suited for such schemes due to its visible-light optical transitions and long-lived metastable states [2]. Furthermore, 532 nm light can be used to drive both the ground S1/2 state and metastable D5/2 state qubit transitions via a 2-photon Raman process with very low scattering error. |
Wednesday, June 1, 2022 9:12AM - 9:24AM |
H09.00007: Towards a scalable mixed-species ion trap quantum computer with one laser-free species Alejandra L Collopy, Hannah M Knaack, Laurent Stephenson, Robert T Sutherland, Stephen B Libby, David T Allcock, John Chiaverini, Andrew C Wilson, Dietrich Leibfried, Daniel H Slichter We discuss progress towards implementing mixed species operation of Ca+-Mg+ ion crystals in a surface-electrode radio-frequency trap. By utilizing quantum logic spectroscopy techniques, the ‘helper’ Ca+ ion can be used to sympathetically cool, prepare a hyperfine ground state of, and non-destructively read out the ‘data’ Mg+ ion [1]. Universal laser-free control of single and multiple Mg+ ions [2], as well as laser-free Ca+-Mg+ entangling operations, are performed using trap-integrated microwave electrodes. Laser-free addressing of individual ions in a trap zone, or controllable sets of ions in multiple zones, can be used to perform simultaneous operations in parallel on many qubits. By removing the need for lasers addressing the Mg+ ion, trap charging due to ultraviolet light and damage to the ‘data’ ion from resonant light crosstalk can both be eliminated. |
Wednesday, June 1, 2022 9:24AM - 9:36AM |
H09.00008: Progress towards tunable mixed-species laser-free interactions with parametric modulation Hannah M Knaack, Alejandra L Collopy, Laurent Stephenson, Andrew C Wilson, Dietrich Leibfried, Daniel H Slichter Co-trapping multiple ion species can offer many advantages for quantum information processing, combining the best qualities of each species. However, such mixed-species operation also poses challenges, and the choice of which species can be co-trapped is often limited by their charge-to-mass ratios. If the charge-to-mass ratios of the species are poorly matched, participation in shared motional modes—especially radial modes—can be highly unequal, which slows motionally-mediated multi-qubit interactions. Parametric modulation of the confining potential enables tunable coupling between motional modes [1], which can be used to assist interactions that are impeded by unequal mode participation. We propose using this technique to speed up mixed-species laser-free quantum logic operations by coupling different radial modes in mixed-species ion crystals. |
Wednesday, June 1, 2022 9:36AM - 9:48AM |
H09.00009: Resource-efficient fully randomized benchmarking Laurent Stephenson, Alex Kwiatkowski, Hannah M Knaack, Alejandra L Collopy, Emanuel Knill, Scott Glancy, Andrew C Wilson, Dietrich Leibfried, Daniel H Slichter Randomized benchmarking is a commonly used technique for estimating the average fidelity of quantum logic operations, measuring the decay of probability of returning to a final fiducial state as a function of the length of a sequence of randomly selected gates. Typically, repeated trials of specific pre-computed random gate sequences are used to reduce the memory requirements on control hardware, limiting the randomness of sequences. By generating pseudorandom numbers on the control hardware itself we can construct gate sequences on the fly; only the instantaneous ideal stabilizers are tracked, reducing memory requirements substantially and enabling gate sequences of arbitrary length. The just-in-time sequence generation allows each sequence to be independently random, which enforces the assumption of depolarizing error channels. Sequence lengths are chosen to extract maximum information in an allotted wall time, making the most efficient use of experiment resources. |
Wednesday, June 1, 2022 9:48AM - 10:00AM |
H09.00010: Metastable State Manipulations in Trapped 133Ba+ Zachary J Wall We present advances in the operation of the synthetic 133Ba+ trappedion |
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