Bulletin of the American Physical Society
50th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics APS Meeting
Volume 64, Number 4
Monday–Friday, May 27–31, 2019; Milwaukee, Wisconsin
Session C05: Trapped Ions |
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Chair: James Siverns, University of Maryland Room: Wisconsin Center 102C |
Tuesday, May 28, 2019 10:30AM - 10:42AM |
C05.00001: Fast Ion Transport in a Surface Electrode Trap Susanna L Todaro, Daniel H Slichter, David J Wineland, Andrew C Wilson, Dietrich Leibfried In the `quantum CCD' architecture for scalable trapped ion quantum computation [1,2], ion qubits are transported between trap zones dedicated to memory, readout, or gate operations. In most prior quantum CCD experiments, ion transport between zones has been performed on timescales much longer than those of typical laser-driven gate operations, representing substantial time overhead. Reducing this overhead by transporting ions faster will in general leave the ions in a higher motional state, requiring substantial recooling before subsequent gate operations. Fast transport with minimal final motional excitation has been demonstrated by transporting in an integer number of ion motional periods [3,4]. However, this scheme has only one parameter (the duration of the transport) that can be tuned to optimize performance experimentally. We report experimental results towards fast ion transport with low net motional excitation in a cryogenic surface-electrode trap using a new scheme offering increased tunability, which may help to transport multiple ions. [1] Wineland et al., J. Res. NIST 103, 259 (1998) [2] D. Kielpinski, C. Monroe, and D. J. Wineland, Nature 417, 709 (2002) [3] A. Walther et al., PRL 109, 080501 (2012) [4] R. Bowler et al., PRL 109, 080502 (2012) [Preview Abstract] |
Tuesday, May 28, 2019 10:42AM - 10:54AM |
C05.00002: Large, Individually-addressable, Multispecies Quantum Information Processor : Performance Marko Cetina, Michael Goldman, Laird Egan, Andrew Risinger, Kevin Landsman, Christopher Monroe Under the IARPA LogiQ program, in a collaboration between universities and industrial partners, we have constructed a complex ion-based quantum processor with the goal of realizing a logical quantum bit. I will report on the performance of our first-generation integrated system, including fidelities of single-qubit and two-qubit gates, crosstalk, operation with long ion chains, syndrome readout and multi-species operation. [Preview Abstract] |
Tuesday, May 28, 2019 10:54AM - 11:06AM |
C05.00003: Realistic high-fidelity protocols for qudit-based quantum computing Brendan White, Pei Jiang Low, Andrew Cox, Rich Rademacher, Matthew Day, Noah Greenberg, Crystal Senko We present on the feasibility of implementing quantum information processing using multi-level qudits encoded within trapped ions. We describe protocols for how current technology may be used to implement high-fidelity state preparation, measurement, and single- and two-qudit gates in a trapped ion framework. A scalable measurement scheme using rapid adiabatic passage to a meta-stable state is presented, along with a discussion of single-qudit gate implementation, and a practical method for implementing two-qudit entangling gates (mediated by collective phonon modes) using a geometric phase approach. From our error estimations, we can achieve better than 99% fidelity for three- and five-level qudit operations and measurement, which will allow us to perform fault-tolerant quantum computing on these platforms. We anticipate that further improvements to the measurement technique and the qudit manipulations could be made to push these fidelities higher. [Preview Abstract] |
Tuesday, May 28, 2019 11:06AM - 11:18AM |
C05.00004: Progress toward a protected subspace qubit in $^{138}\textrm{Ba}^+$ ions Martin Lichtman, Ksenia Sosnova, Allison Carter, Sophia Scarano, Clayton Crocker, Christopher Monroe The commonly used $^{138}\textrm{Ba}^+$ ion has zero nuclear spin and hence no magnetically insensitive Zeeman states. Following the proposal of Aharon, Drewsen, and Retzker, PRL 111, 230507 (2013), we seek to create states that have effective zero magnetic moment by creating superpositions of Zeeman levels in the $5D_{3/2}$ manifold. These synthetic qubit states are the dark eigenstates of the Hamiltonian in the presence of a driving field that creates a protected subspace. We report the creation of effective zero magnetic moment states using both STIRAP and Raman processes, including a novel detection scheme to verify the population distribution in the D manifold, and coherent flopping between these synthetic qubit states. The internal phase of the superposition states is verified through the flopping behavior as compared to simulations. An increase in coherence time in the absence of magnetic field stabilization is shown compared to $6S_{1/2}$ and $5D_{3/2}$ Zeeman qubits. [Preview Abstract] |
Tuesday, May 28, 2019 11:18AM - 11:30AM |
C05.00005: Sideband Cooling of Ytterbium Brandon Ruzic, Melissa Revelle, Peter Maunz Trapped ions continue to be at the forefront of experimental platforms for precisely controlled quantum systems. In particular, linear chains of Yb ions are now counted among the most promising architectures for quantum computing. However, the high-fidelity entangling gates required for quantum information processing require that the motional degrees of freedom be kept at ultracold temperatures. Although these temperatures have been reached before, we have devised a novel sideband-cooling technique for Yb ions with a few advantages. By using the D3/2 state, this technique requires a simple laser system that is separate from the qubit lasers. It also avoids decay into the F7/2 state, which is a known complication when using the D5/2 state. We have experimentally demonstrated this technique on a single Yb-171 ion, and the resulting cooling rate is comparable to using the qubit lasers for cooling. The rate also shows good agreement with our theoretical model. These results suggest that this technique can be used to cool a chain of Yb ions and enable high-quality quantum gates. This~research~was~funded,~in~part,~by~the~Office~of~the~Director~of~National~Intelligence~(ODNI),~Intelligence~Advanced~Research~Projects Activity~(IARPA). Sandia National Laboratories is operated by NTESS, a wholly owned subsidiary of Honeywell International, for the US Department of Energy's NNSA under contract DE-NA0003525. [Preview Abstract] |
Tuesday, May 28, 2019 11:30AM - 11:42AM |
C05.00006: Resonant Rydberg lines of a single trapped Rydberg ion: coupling to trap RF potential and fabircation-induced electric fields Mariusz Pawlak, Hossein Jooya, Hossein R. Sadeghpour An accurate numerical scheme is presented to calculate and analyze the spectral line shape and broadening of a single highly excited Rydberg ion in a Paul trap. The energy spectra of a free highly excited $Ca^+$ are accurately calculated for \textit{s}, \textit{p}, \textit{d}, \textit{f}, and \textit{g} states (up to $n=64$), using the parametric one-electron valence potential with spin-orbit coupling. The coupling of the ion and Rydberg electron to the trap potential is implemented within a Floquet formalism. The alternating \textit{axial} electric field noise due to the applied RF, and the oscillating \textit{radial} electric field emanating due to the trap fabrication are incorporated into the Floquet calculations. Detailed comparison with available observation (Feldker et. al, PRL 2015) is made. [Preview Abstract] |
Tuesday, May 28, 2019 11:42AM - 11:54AM |
C05.00007: Phonon Tomography with Ancilla Modes in Trapped Ion System Kihwan Kim, Yao Lu, Shuaining Zhang, Leonardo Banchi, Guanhao Huang, Jingning Zhang, Myungshik Kim, Wentao Chen Boson tomography is a fundamental physical problem which has a capacity to show the power of quantum computation. While it has been considered mostly for linear optical systems with photons, phonons for trapped ions are also a good candidate to realize the full tomography of their quantum states. A recent proposal by L. Banchi et al. (PRL 121, 250402 (2018)) shows that with ancilla vacuum modes, the number of measurement settings required for the experiment can be reduced. Here, we demonstrate, for the first time, a full phonon tomography of a two-mode number-restricted input phonon state with a beam splitter operation and projective measurements. Then we use up to two ancilla vacuum modes to realize the reduction of settings for the tomography of this two-mode input state. Our experiment demonstrates a new way to realize boson tomography with minimal resources for a trapped ion system which can be generalized to other physical systems. [Preview Abstract] |
Tuesday, May 28, 2019 11:54AM - 12:06PM |
C05.00008: Quantum Simulation of 2D spin lattices in a linear chain of trapped ions Sainath Motlakunta, Fereshteh Rajabi, Yi Hong Teoh, Manas Sajjan, Chung-You Shih, Nikhil Kotibhaskar, Roland Hablutzel, Rajibul Islam Trapped ions, a leading candidate for quantum simulation, are most readily trapped in a linear chain, have limited ability to simulate arbitrary higher dimensional models. Here, we describe an analog and analog-digital hybrid quantum simulation protocols that leverage the phonon-mediated long range (Molmer-Sorensen) interactions between ion spins to mimic the interaction graph of 2D lattices. The traditional analog protocol requires individual control of spins and phonon modes. Here, we enhance the experimental feasibility by employingneural networks [1] to efficiently optimizethe required experimental configuration. The hybrid protocol [2], dynamically modifies the targeted interactions between all-to-all coupled spins that are feasible in current experiments. The hybrid protocol scales favorably for lattices with certain symmetries, e.g. O(N)control pulses are required to simulate a square lattice of N sites. We acknowledge financial support from U Waterloo, US ARO, NSERC Discovery grant, and TQT (CFREF). ~ [1] Collaboration with Marina Drygala and Roger Melko [2] Rajabi et al, arXiv 1808.06124 (collaboration with Ashok Ajoy, UC Berkeley and Qudsia Quraishi, ARL). [Preview Abstract] |
Tuesday, May 28, 2019 12:06PM - 12:18PM |
C05.00009: A Trapped Ion Quantum Simulator for Two-Dimensional Spin Systems Marissa Donofrio, Yuanheng Xie, AJ Rasmusson, Noah Schlossberger, Andrew Henderson, Michelle Lollie, Phil Richerme Quantum simulation of complex materials addresses fundamental problems in systems that cannot be analytically solved due to exponential scaling of the Hilbert space with increasing particle number. Simulations have been realized in various systems including trapped ion chains, optical lattices, and superconducting circuits. Ion chains in particular have had great success investigating one-dimensional quantum interacting spin models. Using 171 Yb$+$ ions, we seek to extend these ideas to two dimensions by exploiting large axial frequencies in an rf Paul trap. Individual spins are embedded in two hyperfine ground states of each ion, and ions are lowered to mK temperatures with laser cooling. Spins can be initialized and allowed to evolve under an effective Hamiltonian created by radiation fields, which can be tuned adiabatically to vary interaction range or geometric frustration. Site-resolved imaging will allow for construction of any N-spin correlation function and characterization of system entanglement. This setup will allow us to address open questions related to geometric frustration, ground states and dynamics of long-range spin models, and formation of exotic phases of matter such as valence-bond states and quantum spin liquids. [Preview Abstract] |
Tuesday, May 28, 2019 12:18PM - 12:30PM |
C05.00010: Simulating cavity quantum electrodynamics with a trapped ion system Guin-Dar Lin, Chen-Yu Lee We theoretically investigate the possibility of constructing a phonon cavity on a large ion crystal. We propose to use optical tweezers to locally pin one or several ions so that they can effectively form cavity “walls” and the subset array between walls contributes to cavity phonons. We calculate the associated cavity properties such as the quality factor, finesse, and loss rate, and find how these quantities scale with tweezers’ strength, “thickness of walls” (number of tweezers), and the cavity local eigenmode spectrum. By coupling the internal states and collective sidebands, we can simulate interesting cavity quantum electrodynamical Hamiltonians. We thus look into the lasing mechanism for phonons with such systems. [Preview Abstract] |
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