Bulletin of the American Physical Society
APS March Meeting 2020
Volume 65, Number 1
Monday–Friday, March 2–6, 2020; Denver, Colorado
Session A02: Advances in Atomic SystemsFocus
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Sponsoring Units: DQI DAMOP Chair: Daniel Slichter, National Institute of Standards and Technology Boulder Room: 105 |
Monday, March 2, 2020 8:00AM - 8:12AM |
A02.00001: Trapped Ion Quantum Computing at Honeywell Russell Stutz Honeywell Quantum Solutions is pursuing a scalable quantum computing architecture based on trapped atomic ions. To this end, Honeywell is developing a broad array of enabling technologies and capabilities, including demonstrations of high-fidelity quantum gate and measurement operations, fast ion transport and re-order, and integration of parallel multi-zone processing of trapped ion qubits to form NISQ devices. We will report recent progress on these and other fronts. |
Monday, March 2, 2020 8:12AM - 8:24AM |
A02.00002: Sandia's Quantum Scientific Computing Open User Testbed (QSCOUT) Christopher Yale, Susan M. Clark, Daniel Lobser, Jessica M. Pehr, Melissa C Revelle, Peter Maunz Trapped ions are a leading candidate for quantum computation due to their high-fidelity gate operations, indistinguishability, qubit connectivity, and routes to scalability. Harnessing these advantages, we are developing the Quantum Scientific Computing Open User Testbed (QSCOUT) based on a trapped-ion quantum register at Sandia, using our microfabricated surface electrode traps to host chains of ions with all-to-all connectivity adaptable to diverse algorithms. Here, we present the experimental development of QSCOUT, the current and anticipated capabilities of the testbed, as well as opportunities for use of this platform. As an open testbed, it will feature fully specified operations and hardware allowing users to modify quantum gates and pulse sequences for desired control. |
Monday, March 2, 2020 8:24AM - 8:36AM |
A02.00003: Building a Logical Qubit-sized Ion Trap Quantum Information Processor Andrew Risinger, Michael L Goldman, Laird Egan, Crystal Noel, Daiwei Zhu, Debopriyo Biswas, Marko Cetina, Christopher Roy Monroe We present the system design and architecture of a trapped ion universal quantum processor with high-fidelity quantum gates and addressing of up to 32 qubits. Our approach takes advantage of individual optical addressing to achieve simultaneous high-fidelity operations on a long chain of 171Yb+ ions, resulting in one of the largest academic general-purpose quantum computers. This framework enables long gate-depth, general-purpose algorithms, with the goal of demonstrating an error-corrected logical qubit. We will also cover advances we have made in the control system, specifically in canceling crosstalk and running long experiments. |
Monday, March 2, 2020 8:36AM - 9:12AM |
A02.00004: Constructing Trapped Ion Quantum Computers Invited Speaker: Kenneth Brown Atomic ion qubits are a promising system for quantum computation with high-fidelity state preparation, measurement, and gates. These systems have already demonstrated complex quantum algortihms from hidden shift problems to quantum simulations. In this talk, I will discuss our experimental work at Duke towards constructing larger ion trap quantum systems. I will also describe the prospects for quantum error correction with trapped atomic ions. |
Monday, March 2, 2020 9:12AM - 9:24AM |
A02.00005: A compact room temperature trapped ion system Yuhi Aikyo, Geert Vrijsen, Tom Noel, Jungsang Kim A trapped ion system is a leading platform for a practical quantum computer. The current gate fidelity is dominated by systematic errors in the control systems delivering the laser beams that drive the gates. The main sources of these errors - mechanical instability and temperature fluctuation - are most effectively addressed by designing compact and robust optical systems. In this work, we present a collaborative work between Duke University and ColdQuanta, where a compact ultra-high vacuum (UHV) chamber operating at room temperature was developed for a trapped ion system. The internal volume of the UHV chamber is only a few cubic centimeters and its vacuum is maintained by a miniaturized ion pump. We demonstrate chain loading of Ytterbium (Yb) ions into a surface trap by ablating a metallic Yb target with a Q-switched Nd:YAG laser. We characterized the vacuum level of this small package by monitoring the hopping rate of an ion in a double well potential, driven by the collision events with background molecules. We also monitored the rate of collision events that cause reordering of the ions in a 6-ion chain containing two isotopes of Yb, one of which appears dark when it is monitored. |
Monday, March 2, 2020 9:24AM - 9:36AM |
A02.00006: A trapped ion system with integrated optics for logical quantum operations Christopher Axline, Karan K Mehta, Roland Matt, Robin Oswald, Chiara Decaroli, Leon Stolpmann, Jonathan P Home Implementing algorithms using quantum error correction in a quantum computer may require on the order of one million physical qubits. Trapped ion systems have shown long lifetimes and exceptional single- and multi-qubit gate fidelities. It will be critical to preserve these high fidelities while creating a scalable trapping and manipulation scheme. With integrated, independent control of trapped ions within a chain, we can limit noise and simplify the sequence of operations required to realize an error-corrected logical qubit. We are implementing two approaches for individual addressing of 40Ca+ ions in a cryogenic ion trap system; the first involves a fiber array imaged onto an ion string, while the second integrates optical waveguides directly within the ion trap chip. In the same setup, we characterize self-stabilized superconducting magnetic field coils for long-lived coherence. We present designs for operation of multiple trapping zones that could be implemented and interfaced as logical qubits. With such a noise-resilient, configurable system, we aim to demonstrate multi-qubit stabilizer readout towards a powerful ion trap quantum processor. |
Monday, March 2, 2020 9:36AM - 9:48AM |
A02.00007: Individual control of an array of neutral atom qubits for quantum computing Brian Lester, Sabrina Hong, Jonathan King, Stanimir Kondov, Krish Kotru, Mickey McDonald, Remy P.M.J.W. Notermans, Alexander Papageorge, Robin Coxe, Prasahnt Sivarajah, Benjamin Bloom Ultracold neutral atoms have emerged as a promising platform for scalable quantum computation. Universal single-qubit control requires high quality state preparation, spatially resolved manipulation, and projective readout of each qubit. For state preparation and readout, neutral atom platforms can apply techniques commonly used in quantum gas microscopes and single atom trapping machines. Furthermore, the ability to isolate the internal spin states of individual neutral atoms from both external fields and neighboring atoms allows for fundamental coherence times exceeding 10 seconds, as demonstrated in recent optical lattice clock experiments. Here, we present initial results on the universal single-qubit control of an array of atomic qubits comprised of neutral strontium atoms. Importantly, the utilized gate scheme enables individual qubit control without relying on global operations that would need to be serialized as the number of qubits is increased. |
Monday, March 2, 2020 9:48AM - 10:00AM |
A02.00008: Integrated optical implementation of multi-ion quantum logic Karan Mehta, Chi Zhang, Maciej Malinowski, Thanh-Long Nguyen, Martin Stadler, Jonathan P Home Practical and useful quantum information processing will require improvements in operation fidelity and robustness, and simultaneously in scale and integration. Ion qubits’ fundamental qualities are promising for long-term systems, but the optics used to precisely control and measure their quantum states are a challenge to scaling. Previous work with single ions has suggested that trap-integrated optics may make this control more robust, and simultaneously parallelizable [1]. We have designed and implemented planar traps with integrated waveguides and grating couplers, for controlling multiple 40Ca+ ions. We measure 1.5 dB direct fiber-to-chip coupling losses, eliminating the need for beam alignment into vacuum systems/cryostats. Using these photonics, we have realized two-qubit entangling gates with fidelities over 97%, with understood errors suggesting significant possible improvement. The experimental realization of high-fidelity quantum logic in this platform suggests it can enable larger systems in multiple zones connected by transport [2]. |
Monday, March 2, 2020 10:00AM - 10:12AM |
A02.00009: Efficient Arbitrary Simultaneously Entangling Gates on a trapped-ion quantum computer Nikodem Grzesiak, Reinhold Blumel, Kristin Beck, Kenneth Wright, Vandiver Chaplin, Jason Amini, Neal Pisenti, Shantanu Debnath, Jwo-Sy Chen, Yunseong Nam Entanglement is a key ingredient in quantum computing. On a trapped ion quantum computer, parallel entangling operations have traditionally been implemented with the help of nonlinear solvers. In this talk, I will present an exact, linear protocol that entangles multiple arbitrary pairs of trapped-ion qubits. The protocol is efficient and can leverage the all-to-all connectivity available on trapped-ion quantum computers to implement up to quadratically many two-qubit gates at the same time. [arXiv:1905.09294] |
Monday, March 2, 2020 10:12AM - 10:24AM |
A02.00010: Teleported CNOT Gate in a Mixed-Species Trapped-Ion System Stephen Erickson, Yong Wan, Daniel Kienzler, Karl Mayer, Ting Rei Tan, Jenny Wu, Hilma Vasconcelos, Scott Glancy, Emanuel H Knill, David J Wineland, Andrew C Wilson, Dietrich Leibfried Scaling up quantum information processing (QIP) can be aided by distributing qubits across multiple processing zones. Universal quantum computation across such an architecture will require entangling gates between qubits in separate zones. Quantum gate teleportation achieves this, requiring only local operations within each zone, a single entangled ancilla pair split between the two zones, and classical communication. Using this protocol, we demonstrate a teleported CNOT gate between two spatially separated 9Be+ ions by means of a split entangled pair of 25Mg+ ions and measure an entanglement fidelity in the interval (0.845, 0.872) at the 95% confidence level. Our demonstration combines many important tools for scaling trapped-ion QIP, including ion separation and shuttling, individually addressed single qubit rotations and detections, same- and mixed-species entangling gates, and real-time conditional feedforward operations. |
Monday, March 2, 2020 10:24AM - 10:36AM |
A02.00011: Laser-free trapped-ion entangling gates with an oscillating magnetic-field gradient at radio frequency Raghavendra Srinivas, Shaun Burd, Robert Tyler Sutherland, Hannah M Knaack, Dietrich Leibfried, David J Wineland, Andrew C Wilson, David Thomas Charles Allcock, Daniel H Slichter We demonstrate a recently proposed method for trapped-ion entangling gates implemented using an oscillating magnetic-field gradient at radio frequency in addition to two microwave magnetic fields symmetrically detuned about the qubit frequency [1]. This technique enables laser-free entangling gates with reduced sensitivity to qubit frequency errors. The experiment is performed in a surface-electrode trap that incorporates current-carrying electrodes to generate the microwave fields and the oscillating magnetic field gradient. Currently, we achieve a Bell-state fidelity of 0.996(2) with ground-state-cooled ions and 0.991(3) for ions cooled to the Doppler limit (nbar=2). The radio-frequency currents used to generate the gradient also give rise to a tunable differential ac Zeeman shift on the two ions which can be turned on and off. While the gate is insensitive to this shift, it can be used independently to perform single ion addressing. This method of addressing does not require additional control fields or rotation of the ion crystal. We can combine this addressing with an entangling gate to create any Bell state from a given initial state. |
Monday, March 2, 2020 10:36AM - 10:48AM |
A02.00012: Quantum hopping of frequency-bin entangled photon pairs Poolad Imany, Navin B Lingaraju, Mohammed S Alshaykh, Daniel E Leaird, Andrew M Weiner Quantum walks of entangled particles have promising applications in simulating many-body physics, as well as in implementing quantum search algorithms. Here, we report continuous quantum walks of a two-photon quantum frequency comb using electro-optic phase modulation to tune the evolution of the state through the quantum circuit. By manipulating the spectral phase of the initial entangled state, we demonstrate either enhanced ballistic energy transport or energy bound states, which are signatures of bosonic and fermionic frequency hopping, respectively. In addition, applying quadratic spectral phase on the initial state creates different subspaces featuring bosonic or fermionic character. We also explore the effect of increasing entanglement dimensionality in frequency domain quantum hopping; our results suggest the potential of our circuit for certifying high-dimensional entanglement. |
Monday, March 2, 2020 10:48AM - 11:00AM |
A02.00013: Improved Light-Matter Interaction in a Thulium Cavity Memory for Quantum Light Storage Jacob Davidson, Pascal Lefebvre, Jun Zhang, Daniel Oblak, Wolfgang Tittel We design and implement an atomic frequency comb quantum memory using a thulium-doped crystal in an impedance matched optical cavity to create absorption of more than 90% of input signal, resulting in a memory efficiency of 27%. This low finesse optical cavity design enables efficient storage over the conventionally large frequency bandwidths ( ≥ 500 MHz) present for single photons and high communication rates. We store one member of a photon pair created through spontaneous parametric down-conversion and, by measuring a value of g(2)=9.3 ± 1.2 > 2 for the cross-correlation function of the photons, verify that the non-classical nature of the light persists after storage in the cavity memory. Using quantum process tomography to measure time-bin qubits after storage in this high-bandwidth memory, we characterize the qubit storage fidelity to be as high as F = 95.0 ± 0.1%, confirming non-classical qubit storage. These results demonstrate progress toward efficient, faithful, and high bandwidth storage of single photon qubits for quantum networking. |
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