Bulletin of the American Physical Society
54th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 68, Number 7
Monday–Friday, June 5–9, 2023; Spokane, Washington
Session K09: Advances in Quantum Gates and Computing with Trapped Ions |
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Chair: Brian McMahon, GTRI Room: 206 D |
Wednesday, June 7, 2023 10:30AM - 10:42AM |
K09.00001: Progress towards laser-free mixed-species gates with a near-motional frequency oscillating gradient Hannah M Knaack, Laurent J Stephenson, Alejandra L Collopy, Christina M Bowers, Andrew C Wilson, Dietrich Leibfried, Daniel H Slichter The choice of ion species for trapped ion quantum processors involves tradeoffs – lighter ions can enable faster interactions and have good qubit coherence times, but the laser wavelengths required for species such as Be+, Mg+, and Al+ are deep in the ultraviolet. The need for ultraviolet lasers can be reduced by performing entangling operations with microwave and rf magnetic field gradients instead, and such interactions have demonstrated high fidelities and improved speeds in recent years. Quantum logic state preparation and readout, together with sympathetic cooling, can eliminate the need for qubit species lasers by incorporating a helper species. However, the choice of helper species is limited because large mass disparities between species can make trapping and loading difficult and impact the efficiency of sympathetic cooling. Combining laser-free entangling gates with sympathetic cooling and quantum logic-based state preparation and readout allows us to take advantage of a lighter qubit ion species without requiring ultraviolet lasers. The addition of tunable parametric coupling between motional modes helps to speed up sympathetic cooling and laser-free entangling operations between ions with imbalanced mode participation. We present progress towards a mixed-ion species laser-free entangling gate with a near-motional oscillating gradient and tunable parametric motional-mode coupling. |
Wednesday, June 7, 2023 10:42AM - 10:54AM |
K09.00002: First Step Towards High-Dimensional Qudit Quantum Computing With Trapped Ions Pei Jiang Low, Brendan M White, Crystal Senko
137Ba+ is an attractive candidate for high-level qudit encoding due to the availability of its many stable and meta-stable states. Utilizing the ground 6S1/2 and the meta-stable 5D5/2 levels, a maximum qudit encoding of up to 25 distinguishable states is possible with our protocol in principle. State preparation and measurement (SPAM) is a necessary first step for quantum computation. We demonstrate a 13-level encoding with 137Ba+ and the experimental SPAM fidelity achieved in our work. |
Wednesday, June 7, 2023 10:54AM - 11:06AM |
K09.00003: In situ measurement and reset of individual qubits with < 1E-3 probability of accidental measurement at the neighbour Nikhil Kotibhaskar, Lewis Hahn, Sainath Motlakunta, Chung-You Shih, Anthony Vogliano, Jingwen Zhu, Yu-Ting Chen, Kazi Islam Trapped ions are a versatile platform for quantum information processing. Precise coherent and incoherent/dissipative manipulation of ion-qubits opens new avenues, such as quantum error correction and simulation of measurement driven quantum phases. Recent experiments gained control over coherent operations at the individual qubit level. However, high fidelity incoherent manipulation of individual ion qubits, such as subsystem measurement and reset, is hard. A fundamental limitation is the irreversible decoherence or accidental measurement of the neighbouring ions while addressing the target ion(s). Current approaches to mitigate this issue include 'shuttling' the ions during incoherent operations, which slows the clock speed of a quantum processor and introduces errors. Here, we demonstrate in situ incoherent operations with <1E-3 probability of accidental measurement of the neighbouring qubits. This is enabled by our holographic optical addressing scheme which allows us to achieve ~8E-5 nearest neighbour intensity crosstalk. In situ incoherent operations will increase the processor speed and facilitate exploration of new types of quantum simulations requiring subsystem measurements. |
Wednesday, June 7, 2023 11:06AM - 11:18AM |
K09.00004: A next-generation trapped ion quantum computing system Yichao Yu, Liudmila Zhukas, Lei Feng, Marko Cetina, Crystal Noel, Debopriyo Biswas, Andrew Risinger, Vivian Zhang, Keqin Yan, Bahaa Harraz, Grant Eberle, Alexander Kozhanov, Christopher Monroe The first generation of a universal trapped ion integrated quantum processor, constructed in a collaboration between our group and industrial partners, was used to perform quantum algorithms with high-fidelity on 13 qubits, and high-fidelity quantum gates with up to 23 qubits. |
Wednesday, June 7, 2023 11:18AM - 11:30AM |
K09.00005: Quantum information processing in mixed qubit type registers of individually addressed 137Ba+ ions Ana S Sotirova, Jamie Leppard, Andres Vazquez Brennan, Fabian Pokorny, Christopher J Ballance We present a quantum computing system that allows for storage and individual addressing of long 137Ba+ chains. The long (~30 s) lifetime of the metastable D5/2 level in barium makes it well-suited for schemes utilising both ground and metastable level qubits[1]. We drive both qubit types with a two-photon Raman process using 532 nm light. We achieve individual addressing with very low cross-talk of our 532 nm beams via a laser-written waveguide device. We also exploit the Stark shifts induced by the individual beams to execute fundamental operations, including mapping between the ground and metastable levels, state preparation, readout, and cooling, on a targeted subset of qubits. |
Wednesday, June 7, 2023 11:30AM - 11:42AM |
K09.00006: Coherent Control of Trapped Ion Qubits with Localized Electric Fields Raghavendra Srinivas, Clemens M Löschnauer, Maciej Malinowski, Amy C Hughes, Rustin Nourshargh, Vlad Negnevitsky, David T Allcock, Steven A King, Clemens Matthiesen, Thomas P Harty, Chris J Ballance We present a new method for coherent control of trapped ion qubits in separate interaction regions of a multi-zone trap by simultaneously applying an electric field and a spin-dependent gradient. Both the phase and amplitude of the effective single-qubit rotation depend on the electric field, which can be localized to each zone. We demonstrate this interaction on a single ion using both laser-based and magnetic field gradients in a surface-electrode ion trap, and measure the localization of the electric field. |
Wednesday, June 7, 2023 11:42AM - 11:54AM |
K09.00007: Standing-wave Mølmer-Sørensen gates on a quadrupole transition Oana Bazavan, Sebastian Saner, Donovan Webb, Raghavendra Srinivas, Gabriel Araneda, David M Lucas, Chris J Ballance Free-space standing waves (SW) are ubiquitous in atomic physics and are often employed for creating spin-dependent forces used for entangling gate operations and neutral atom trapping. Recently, there has been an interest in gaining control over the phase of the SW at the position of trapped ions [1] due to promising applications in quantum metrology, quantum information processing with continuous variables [2] and quantum simulations [3]. In our experiment, we make use of a phase-stabilised SW to coherently suppress a non-computing error source in the conventional Mølmer-Sørensen (MS) interaction. |
Wednesday, June 7, 2023 11:54AM - 12:06PM |
K09.00008: Error mitigation on global entangling gates with trapped ions Zhengyang Cai, Pengfei Wang, Wentao Chen, Jialiang Zhang, Jing-Ning Zhang, Kihwan Kim Quantum error mitigation is an algorithmic method to improve the accuracy of output results of a quantum circuit without quantum error corrections that requires plenty of quantum resource overheads. It has been extensively explored in noisy-intermediate-scale-quantum (NISQ) systems. Quantum error mitigation, in particular, a probabilistic error cancelation method has been demonstrated for two-qubit gates and but it has not been applied to more than two-qubit gates because of the difficulty in characterizing quantum processes of multi-qubit gates. Recently, a few methods for characterizing multi-qubit operations and mitigating errors have been proposed with the assumption of a sparse error model or matrix product representation. We apply the quantum error mitigation methods to global entangling gates [1] that make all-to-all connections and provide efficient quantum computations. Our finding can be an important means for extending systematic error-mitigation schemes toward practical quantum advantages. |
Wednesday, June 7, 2023 12:06PM - 12:18PM |
K09.00009: A spin-dependent kick using a single 20 ps laser pulse Randy P Putnam, Paul Hamilton, Wes Campbell We report the observation of impulsive momentum kicks of trapped ions whose sign depends upon the electron's spin projection. Using a pair of perpendicular beams from a mode-locked, 532 nm laser, we drive a stimulated Raman transition between two Zeeman levels that completely flips the ion's spin as well as applies a spin-dependent momentum kick in tens of picoseconds. The spin-dependent nature of the force is verified by the decay and subsequent revival of Ramsey fringe contrast when a pair of such kicks is separated by a trap period. Impulsive, state-dependent kicks of this type may be useful for interferometric inertial sensing and high-speed quantum gates. |
Wednesday, June 7, 2023 12:18PM - 12:30PM Withdrawn |
K09.00010: A low noise 532nm laser system for driving Raman transitions in trapped 137Ba+ Jamie D Leppard, Ana S Sotirova, Andres Vazquez-Brennan, Fabian Pokorny, Christopher J Ballance In Ba+, the long lived 5D5/2 metastable level, together with the 6S1/2 ground level, allows for the implementation of multiple qubit types using only one ion species [1]. This enables advanced control techniques such as in-sequence cooling and mid-circuit measurements. These techniques are required for many error correction schemes. For qubits implemented in either level, a two-photon Raman process can be used to drive transitions with very low scattering error [2]. |
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