04.17.24 -- Measurement-Induced Heating Paper on the arXiv
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Heating processes are known to be detrimental to the operation of trapped ion quantum devices. The most well-known mechanism – anomalous heating – is such a serious consideration that modern ion trap designs, fabrication processes, and operating environments all take anomalous heating into account. Here, we report the observation of a different kind of heating, induced by measurement of a trapped ion quantum state. To our surprise, we find that this measurement-induced heating rate dominates over anomalous heating by a factor of ~30. Through detailed theoretical modeling and experimental data, we conclude that if left unmitigated, measurement-induced heating will present a substantial roadblock for performing high-fidelity quantum operations following a mid-circuit measurement.
The article is currently available here, or on the arXiv.
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02.16.24 -- Interaction Graph Engineering Paper published in New Journal of Physics
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Trapped-ion quantum simulators have demonstrated a long history of studying the physics of interacting spin-lattice systems using globally addressed entangling operations. Yet despite the multitude of studies so far, most have been limited to studying variants of the same spin interaction model, namely an Ising model with power-law decay in the couplings. Here, we demonstrate that much broader classes of effective spin-spin interactions are achievable using exclusively global driving fields. Specifically, we find that these new categories of interaction graphs become achievable with perfect or near-perfect theoretical fidelity by tailoring the coupling of the driving fields to each vibrational mode of the ion crystal, or by shaping the trapping potential to include specific anharmonic terms. These tools broaden the reach of trapped-ion quantum simulators so that they may more easily address open questions in materials science and quantum chemistry.
The article is currently available here, or at the New Journal of Physics site.
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08.17.23 -- Hydrogen-Bond Dynamics Paper Published in the Journal of Physical Chemistry Letters
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Calculating the observable properties of chemical systems is a promising application of quantum information processing. Here, in collaboration with the QSCOUT program at Sandia National Labs, we introduce a new framework for solving generic quantum chemical dynamics problems using an ion-trap quantum processor. For the first time, we experimentally encode the dynamics of an oscillating proton within hydrogen bonded system using a trapped-ion quantum computer. Following the experimental creation and propagation of the shared-proton wavepacket on the ion-trap, we extract measurement observables such as its time-dependent spatial
projection and its characteristic vibrational frequencies to spectroscopic accuracy.
The article is currently available here, or on the J. Phys. Chem. Site.
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05.08.23 -- Senator Todd Young Visits the Lab
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Indiana Senator Todd Young, a supporter of the CHIPS Act and the National Quantum Initiative, came by campus today to learn more about our trapped-ion quantum information research and to tour the lab. He considers efforts in quantum to be "an investment in our national security" that will create jobs in the "industries of the future."
More about the visit can be found in a Herald-Times story available here.
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11.01.22 -- Yuanheng Xie Defends his Ph.D.!
08.08.22 -- Marissa D'Onofrio Defends her Ph.D.!
10.21.21 -- Optimized Sideband Cooling and Thermometry paper published in PRA as Editors' Suggestion
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Over the last three decades, the majority of trapped-ion experiments have relied on resolved sideband cooling to prepare systems near their ground motional state. Here, we have developed a framework that allows for calculation of the optimal sideband cooling pulse sequences for arbitrary experimental conditions, alongside a new measurement technique to determine the final temperature of sideband cooled ions with minimal bias. Both ideas are validated by performing thermometry following an optimized sideband cooling sequence, using our trapped Yb-ion system.
The article is currently available here, or on the PRA Site.
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07.09.21 -- 2D blade-trap paper on the arXiv
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This work presents the design and experimental demonstration of a new linear rf trap, which is capable of both (a) trapping ion crystals in the "radial-2D" phase (where both principal axes lie in the radial direction), and (b) achieving site-resolved imaging of the ions in this geometry, showing their native 2D-triangular lattice configuration. This result builds on our group's prior work, which validated radial-2D crystals for quantum simulation experiments but could only image these crystals from the side. Here, we show the open-endcap design, fabrication techniques, and electronics necessary for confining up to 29 ions in 2D arrays.
The article is currently available here, or on the arXiv: 2107.03471.
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06.09.21 -- 2D Ion Crystals paper accepted to PRL!
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In this paper, we report the first experimental study of radial 2D ion crystals in a linear Paul trap. This crystal geometry is the basis of several theoretical proposals in quantum information, and has led to breakthroughs in the Penning trap community, but has been largely unexplored in rf traps. We study and characterize ion crystals in this phase, finding that micromotion effects are essentially constrained to the radial plane. Moreover, we find that the transverse vibrational modes remain isolated and cold, opening the way for their use in quantum information processing experiments.
The article is available here, or on the PRL site.
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05.31.21 -- Lab Talks at DAMOP 2021
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Three of our lab members will be presenting their work at DAMOP this year. Jiafeng Cui will discuss "Development of a Portable Ion Trap for the Study of Ions under High-dose Radiation" in session C08; Marissa D'Onofrio will be in the same session, presenting the "Characterization and Control of Radial 2D Crystals in a linear Paul Trap." Finally, AJ Rasmusson will share his work on "Machine learning estimation of optimal resolved sideband cooling strategies" in session Z05. |
05.21.21 -- 'Floquet Gauge Pump' paper published in Physical Review Letters
In this collaborative work with the Seradjeh and Ortiz groups at IU, we introduce the concept of a `Floquet gauge pump' as a probe for topological or ordered phases in interacting many-body systems. We apply the idea to a transverse-field XY model with periodically-driven couplings, which gives rise to both (a) dynamically-generated Dzyaloshinsky-Moriya interaction terms, and (b) a magnetization current that reveals the ground-state degeneracies that distinguish the ordered and disordered phases. Importantly, this idea is directly applicable to trapped-ion many-body systems, and can be implemented with current ion-trap technology. The article is available here.
05.07.21 -- Radiation Effects on Trapped-Ion Qubits
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Recent work from teams at MIT/Pacific Northwest National Labs and UCSB/Google has shown that radiation from low-dose gamma sources, or from cosmic rays, are sufficient to cause decoherence and correlated failures in superconducing qubit systems. However, to date no studies of radiation effects on trapped-ion qubits has yet been performed. In this work, we expose our trapped ion system to a variety of alpha, beta, and gamma sources; we find no quantifiable degradation of ion lifetimes, coherence times, gate fidelities, or heating rates in the presence of any tested source. These findings are encouraging for the long-term prospects of using ion-based quantum information systems in extreme environments, indicating that much larger doses may be required to induce errors in trapped-ion quantum processors.
The article is available here, or on the arXiv: 2105.02753.
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04.07.21 -- Quantum Simulation Review Article published in Reviews of Modern Physics
Ion trap quantum simulation is now nearly 10 years old, and the field has grown tremendously in the past decade. Together with colleagues from Univ. of Maryland, UCLA, Tsinghua Univ., Colorado School of Mines, Middlebury College, Univ. of Waterloo, Rice Univ., and UC Berkeley, we have posted a comprehensive review article on ion trap quantum simulation. We recount experiments from the very early days -- involving quantum phase transitions with just 2 ions -- all the way to more recent work on nonequilibrium quantum dynamics with up to 53 spins. The article is available here.
03.15.21 -- Mapping Quantum Chemistry Problems to Ion Traps
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In this work, we propose a new method for solving the quantum time-evolution of nuclei in quantum chemistry by mapping their behavior onto ion-trap quantum simulators. Many quantun chemistry problems of interest require consideration of both electrons and nuclei; electronic structure has recently been the focus of some implementations on quantum hardware, but no known method has been discovered to treat the nuclei. Here, we directly determine the local fields and spin-spin couplings needed to control Ising-type spin-lattice dynamics which emulate the time evolution of molecular systems.
The article is available here, or on the arXiv: 2103.07420.
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08.18.20 -- Yuanheng and Marissa presentation to QED-C
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Congratulations to Yuanheng and Marissa, who were selected to present their research at the Quantum Economic Development Consortium (QED-C) student poster session. Their joint talk has been recorded and is available on Youtube here: https://www.youtube.com/watch?v=M0C_QTvqazg&t=1155s |
06.21.19 -- First Ions!
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The lab hit a big milestone today with the detection of our first trapped ions. Images show the confinement of one, two, and a chain Ytterbium ions in a linear rf trap. The ions are cooled to approximately 500 microKelvin and are separated by ~10 micron. |
05.21.19 -- Marissa D'Onofrio Talk at DAMOP
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Marissa will be speaking at DAMOP 2019, on "A Trapped Ion Quantum Simulator for Two-Dimensional Spin Systems." (Abstract here). The talk is in session C05, Tuesday May 28, 10:30am-12:30pm, in room 102C. If you're at DAMOP, go say hello! |
05.31.18 -- Michelle Lollie, local celebrity
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Our own Michelle Lollie has recently been featured in a news article published in Nature, along with an associated podcast, about the APS Bridge Program. The links include some nice quotes, a video interview, as well as some action shots from in the lab. Well done, Michelle! |
02.12.18 -- Cryogenic Ion Trapping paper on the arXiv
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Large-scale trapped ion quantum simulation will require very low vacuum pressures to minimize the collision rate between ions and background gases. One way to achieve low pressures is to build an ion trap inside a cryogenic environment, which can reduce the collision rates by several orders of magnitude. At Maryland I designed a cryogenic ion trap to accomplish this goal, and it has now been made operational due to the efforts of the Maryland team. The picture to the left shows ~120 Yb+ ions trapped in a linear chain; the link to the full paper is here: "Cryogenic Trapped-Ion System for Large Scale Quantum Simulation" |
08.29.17 -- New paper published in Science Advances
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In nature, it is rare to find examples of systems that *fail* to thermalize. Typically, this requires some hidden symmetry or conserved quantity of motion (as in a harmonic oscillator). In this paper, we have observed a quantum system that fails to thermalize, even though there are no conserved quantities. The system becomes trapped in a "prethermal" state due to an emergent double-well potential felt by the spin excitations. Thermalization can only happen after exceptionally long times, which grow even longer as the size of the system is increased. Read the full paper: "Observation of Prethermalization in Long-Range Interacting Spin Chains". |
01.18.17 -- How to Create a Time Crystal
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Time crystals, which break time-translational symmetry in the same way that ordinary crystals break spatial-translational symmetry, have been a hot topic of debate in the literature in the past few years. Recently, a theoretical proposal has shown how one could be created in the lab, inspiring two experimental demonstrations. Read the full story here. |
09.20.16 -- 2D Paper Published in PRA
A manuscript proposing the use of "2D ion crystals in radiofrequency traps for quantum simulation" has now been published in PRA PRA 94, 032320 (2016). This work lays the theoretical foundation for the experiment that will be built over the next year or two in the lab.
07.12.16 -- New paper on the arXiv
Ion trap quantum simulators have successfully implemented Ising and XY spin models, but Heisenberg models have remained elusive. In collaboration with Alejandro Bermudez, Luca Tagliacozzo, and German Sierra, we propose a way to achieve this long-sought capability using currently available technology: "Long-range Heisenberg models in quasi-periodically driven crystals of trapped ions," arXiv: 1607.03337.
05.18.16 -- New paper on the arXiv
A manuscript proposing the investigation of "String order via Floquet interactions in atomic systems" has now been posted on the arXiv: 1605.05738. This work, in collaboration with Tony Lee and Yogesh Joglekar, shows how non-local correlations, known as string order, can arise in periodically driven trapped ion systems.
03.16.16 -- Let there be (369.5 nm) light
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The new 369 nm laser system was successfully installed this morning, providing an impressive 1 WATT of beautiful blue light. The system starts with 10 W of 532 nm light pumping a Ti:Saph crystal, outputting a 739 nm beam which is then frequency doubled. Thanks, M-Squared! |
02.01.16 -- Optics Tables Installed
Just a few days after construction was completed, the optics tables have been moved in and installed. Three tables form a large "U" work area, with two 4' x 12' tables and one 4' x 10'. See pictures...
01.27.16 -- Construction Complete!
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After 7 months of construction, an empty room is now capable of hosting an atomic physics laboratory. Upgraded electrical power, dedicated air handling for improved temperature stability, new counters and cabinetry, new lighting, and a large equipment support platform will be sure to make the ions happy. |
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