Bulletin of the American Physical Society
APS March Meeting 2023
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session T38: Quantum Dots, Lanthanide Dopants, Molecules and Magnetism |
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Sponsoring Units: DMP Chair: Florian Dirnberger, Technical University of Dresden Room: Room 230 |
Thursday, March 9, 2023 11:30AM - 11:42AM |
T38.00001: Exploring erbium-doped ceria as a new platform for telecom-wavelength quantum memory Gregory Grant, Jiefei Zhang, Kathryn E Sautter, Sean E Sullivan, Manish Kumar Singh, Ignas Masiulionis, Jessica B Martins, Connor P Horn, Rishi Chebrolu, John W Freeland, F. Joseph Heremans, Supratik Guha Scalable solid-state quantum memory systems that operate at telecom wavelengths are essential for building wide-area fiber optic-based quantum networks. A particularly promising platform for such a quantum memory is erbium-doped ceria (Er:CeO2), which combines the shielded telecom-wavelength (~1.5 µm) 4f-4f transition of erbium with the long (47 ms) predicted spin coherence time of CeO2 [1]. Here, we demonstrate growth of epitaxial Er:CeO2 thin films using molecular beam epitaxy (MBE) with controlled crystal quality and Er concentration (0.01% and lower). We present a study of the optical properties of a resonantly-excited Er ensemble, which shows long excited state lifetimes (up to 6 ms) and well-resolved crystal field splitting with narrow inhomogeneous peaks (<100 GHz). Further optical investigation also yields spectral diffusion-limited homogeneous linewidths that are sufficiently narrow to suggest that Er:CeO2 may be a candidate for exploring quantum memory nanophotonic devices. Overall, we present a viable platform for scalable and usable quantum memories based on erbium-doped cerium oxide. |
Thursday, March 9, 2023 11:42AM - 11:54AM |
T38.00002: The role of the dopant on electronic structure of Er-doped oxides for quantum memory Jessica Barbosa Martins, Gregory Grant, Kathryn E Sautter, Rishi Chebrolu, Supratik Guha, John W Freeland Rare earth ion defects in solid-state hosts are excellent candidates for applications in quantum communication technologies as qubit systems, due to their inherent spin-photon interface and long coherence times. [1] Er3+ is an especially promising candidate due to its 4I15/2 → 4I13/2 transition in the telecom C-band. This classically-forbidden telecom transition is made accessible by placing Er3+ ions within a crystal host, which makes the transition sufficiently bright to use for quantum communication. Oxides are an excellent class of hosts for rare-earth ions due to their straightforward growth even at high purity and expected overall good coherence times when hosting defects. [2] Here, we show that linewidths in photoluminescence excitation spectra vary with dopant concentration and growth conditions. However, the causes for this variation are unclear. X-ray absorption spectroscopy (XAS) is an element-specific technique broadly applied for local electronic structure characterization in materials. In this work, we performed XAS at the Advanced Photon Source to probe the electronic structure of Er-doped oxides as a function of the doping level. This information is crucial for controlling the tunability of excited state lifetimes and rare-earth defect linewidths in such systems. |
Thursday, March 9, 2023 11:54AM - 12:06PM |
T38.00003: Ab initio Crystal Field Splittings for Lanthanide Dopants in Oxide Materials for Quantum Information Yueguang Shi, Michael E Flatté Lanthanide dopants in oxide hosts provide excellent spin-photon interfaces for quantum technologies, including by mediating microwave to optical quantum transduction (converting a collective spin excitation to an optical excitation), and for quantum memories. The description of magnetic dipole transitions in lanthanides using model Hamiltonians principally relies on existing experimental fit parameters for terms in the Hamiltonian like the effect of the crystal field on the 4f elections. [1] |
Thursday, March 9, 2023 12:06PM - 12:18PM |
T38.00004: Designing stoichiometric materials with Eu3+ for photon-based quantum information storage Zachary W Riedel, Donny R Pearson, Elizabeth A Goldschmidt, Daniel P Shoemaker Rare-earth cations are a promising platform for quantum information storage because of their long coherence times and well-shielded 4f orbital optical transitions. Though systems under study typically have dilute rare-earth cation concentrations, this leads to inhomogeneity within the structure and thus broadens the linewidth of critical hyperfine transitions. Stoichiometric rare-earth crystals, specifically those with Eu3+, offer a promising alternative for finding naturally narrow inhomogeneous linewidth materials. Promising candidates have been selected from experimental and computational databases. Additionally, unrealized stoichiometric compounds with mononuclidic cations and large predicted Eu3+ separation have been predicted to be stable with density functional theory energy calculations. Single crystals of several materials, including metal-organic frameworks and oxides, have been grown. Once made, their environmental stability and intrinsic defects are monitored with diffraction and spectroscopy techniques. Cryogenic photoluminescence excitation measurements are then used to probe the linewidth of the important 5D0→7F0 transition of Eu3+, revealing critical design factors. |
Thursday, March 9, 2023 12:18PM - 12:30PM |
T38.00005: In situ charge detection with single Quantum Dot Molecules Mark Woodall, Adityaa Bajpai, Zachary von Jena, Allan S Bracker, Samuel G Carter, Michael Scheibner Excitons hosted in quantum dot molecules (QDMs) present unique opportunities to directly investigate the physics of interacting quantum states at the single-charge scale. These systems are highly sensitive to small fluctuations in the local environment, making them suitable for in situ nano-scale monitoring. We describe the predicted spectral patterns of a single QDM under the influence of nearby charge states for the spatially direct and indirect neutral excitons and propose a means to utilize the trion state to break symmetry and distinguish between positive and negative charges. Under lifetime-limited conditions, we calculate that the indirect exciton demonstrates μm-scale single charge sensitivity. Using electric-field dispersed photoluminescence spectroscopy, we observe splittings in the emissions of several epitaxially-grown InAs/GaAs QDMs embedded in nipip diode samples that demonstrate strong consistency with predictions and indicate the presence of single charge interactions at distances of up to 100nm. |
Thursday, March 9, 2023 12:30PM - 12:42PM |
T38.00006: Electrostatic definition and control of quantum dots in semiconductor lead telluride nanowires Seth A Byard, Maksim Gomanko, Sergei Sheludiakov, Sander G Schellingerhout, Erik P. A. M. Bakkers, Sergey M Frolov PbTe is a IV-VI narrow band gap semiconductor with a large dielectric constant of over 1000. This dielectric constant leads to a strong suppression of Coulomb blockade, which allows for the direct spectroscopy of spin and orbital states in quantum dots. In this talk, we present our progress in defining and manipulating quantum dots in PbTe nanowires using top-gate electrodes. We specifically focus on the use of these gates to attempt fine control of quantum dot states and to define double quantum dots electrostatically in the same nanowires. We also discuss the fabrication methods used to create our devices. |
Thursday, March 9, 2023 12:42PM - 12:54PM |
T38.00007: Model Study on Effect of S=1 Central Spins to Spin Decoherence Haechan Park, Silas Hoffman, Xiao Chen, Hai-Ping Cheng We theoretically study mechanisms for decoherence in molecular magnets displaying a clock transition. While it is known that nearby protons are the major source of spin decoherence away from the clock transition, it has been demonstrated that central spins are largely insensitive to nuclei at the clock transition. Although the dominant mechanism for decoherence at the clock transition is unknown, recent experimental data on molecular magnetic crystals indicates that the decoherence time depends on the density of central spins. In this talk, we consider precisely this dependence by simulating a model S = 1 qubit coupled to many other central spin. By changing the magnitude of the dipole interaction between the qubit and other central spins, we effectively simulate the density of central spins in a molecular magnetic crystal. |
Thursday, March 9, 2023 12:54PM - 1:06PM |
T38.00008: Quantum-information theory of magnetic field influence on circular dots with different boundary conditions Oleg Olendski, Hibah Shafeekali Influence of the transverse uniform magnetic field B on position (subscript ρ) and momentum (γ) Shannon quantum-information entropies Sρ,γ, Fisher informations Iρ,γ and Onicescu energies Oρ,γ is studied theoretically for the 2D circular quantum dots whose circumference supports homogeneous either Dirichlet or Neumann boundary condition. Comparative analysis reveals similarities and differences of the surface influence on the properties of the structure. A conspicuous distinction between the two spectra are crossings of the Neumann energies with the same radial quantum number n and adjacent non-positive angular indices m. At the growing B, either system undergoes Landau condensation when its characteristics turn into their uniform field counterparts. It is shown that for the Dirichlet system this takes place at the smaller magnetic intensities; e.g., the n=m=0 Dirichlet sum Sρ+Sγ on its approach to the fundamental limit 2(1+ln π) is at any B smaller than the corresponding Neumann sum what physically means that the former geometry provides more total information about the position and the motion of the particle. Comparison with electrostatic harmonic confinement is performed. Physical interpretation is based on the different roles of the two BCs and their interplay with the field: Dirichlet (Neumann) surface is a repulsive (attractive) interface. |
Thursday, March 9, 2023 1:06PM - 1:18PM |
T38.00009: Direct Detection of Magnetoelectric effect in Fe3 Trimer using a tunnel diode oscillator detector. Marc L lewkowitz, Johnny L Adams, Neil S Sullivan, Ali Sirusi, Ping Wang, Michael Shatruk, Vivien Zapf Single-molecule magnets have many potentially useful applications. Their ability to maintain persistent magnetic states could allow them to be used for classical memory devices, and they may be useable as a quantum bit for computation. The ability to manipulate the magnetic state of a single-molecule magnet through an electrically driven magnetoelectric effect is especially appealing. Electric fields do not require a persistent current to maintain, and thus can be varied on small time and length scales. We report evidence of a change in the magnetic susceptibility of an Iron 3 single-molecule magnet trimer due to an applied electric field of approximately 16 ppb per kV/m. These results represent a direct measurement through use of a tunnel diode oscillator as a susceptometer. These results were conducted between 8 and 20 Kelvin with a maximum applied field of 62 kV/m. We also report preliminary results on other single-molecule compounds. |
Thursday, March 9, 2023 1:18PM - 1:30PM |
T38.00010: Distance Dependance of Proximity Exchange in a Molecular Quantum Magnetic Sensor Kathleen R Mullin, James M Rondinelli Molecular color centers, like Cr(o-tolyl)4, show promise as a flexible platform for quantum magnetic sensing and share many similarities to conventional sensors, like diamond NV centers. In 2D magnetic materials, such as CrI3, large discrepancies in magnetic fields have been measured by different methods. We propose that molecular color centers can be used to address this discrepancy by allowing for a single sensing modality to be used over a wider range of distances and orientations. Prior studies have suggested proximity exchange, between the magnetic substrate and sensor, may be responsible for the discrepancies. To that end, we used density functional theory calculations and magneto-static modeling to understand how proximity exchange and dipolar interactions impact the excited states in the Cr(o-tolyl)4 molecule, which would be probed using optically detected magnetic resonance. We show proximity exchange dominates at short distances due to molecule-substrate interactions, but at further distances the molecule behaves as a typical magnetic sensor, with magneto-static effects dominating changes to the energy of the excited state. Our models effectively demonstrate how a molecular color center could be used to measure the magnetic field of a 2D magnet and the role of important distance-dependent interactions that contribute to the field. |
Thursday, March 9, 2023 1:30PM - 1:42PM |
T38.00011: Electrical Initialization and Readout of Triplet Spins Taylor Wagner Research into new classes of organic materials has revealed promising quantum phenomena, which yield unique advantages for spintronic, quantum sensing, and quantum computing fields. We present work on devices that incorporate two relatively new organic spin phenomena, namely singlet fission (SF) and chirality induced spin selectivity (CISS), as a room temperature initialization and readout mechanism of triplet spins. Promising gate operations and coherence times have already been demonstrated with triplet exciton spin transfer using optical techniques, but a key challenge is the ability to address individual molecular spins. Polycrystalline pentacene is chosen as the active layer, as the high carrier mobility and highly efficient SF produces spin-spin interactions that are electrically detectable under an applied magnetic field. (PEA)2PbI4 perovskite acts as the CISS layer, injecting only spin polarized carriers, eventually purifying the triplet complexes to essentially initialize in a direction parallel with the applied field. Using a complete quantum kinetic model and orientation dependent magnetoresistance as the detection mechanism, these devices provide promising first steps in the room temperature initialization and readout of molecular triplet spins. |
Thursday, March 9, 2023 1:42PM - 1:54PM |
T38.00012: Coherent Interactions and Entanglement of Hydrogen Molecules in the STM Junction Yunpeng Xia, Likun Wang, Dan Bai, Wilson Ho Ultrashort THz pulses can be used to excite single hydrogen molecules (H2) in the junction of Scanning Tunneling Microscope (STM), whose dynamics manifest itself as coherent oscillation through the pump-probe measurements. By tailoring the oscillation frequency through external bias, we report two spectral signatures of the interaction among multiple H2 molecules. First, the avoided level crossing featured by energy gaps ranging from 20 to 80 GHz were observed, as a result of the level repulsion between two H2 molecules. Second, the tip can sense the signal of H2 outside the junction through the projective measurement on the H2 inside the junction, owing to the entangled states created through the interaction. Dipolar-type interaction was incorporated in the two-level system (TLS) model of H2, enabling us to accurately reproduce the aforementioned behavior. Our results reveal the peculiar interplay among H2 molecules and allow us to envision further quantum operations of these polar molecules on surfaces. |
Thursday, March 9, 2023 1:54PM - 2:06PM |
T38.00013: Magnon Engineering in Vanadium Tetracyanoethylene Donley Cormode, Robert Claasen, Zoe Phillips, Ezekiel W Johnston-Halperin
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Thursday, March 9, 2023 2:06PM - 2:18PM |
T38.00014: Electronic states and magnetism driven quantum phenomena in pristine and Ce substituted Ga2O3 Yogendra Limbu, Michael E Flatté, Durga Paudyal
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