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Choi, Soonwon

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Soonwon

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Choi, Soonwon

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2015 - 20195

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Author's Publications: search.filters.isAuthorOfPublication.75e39f5e-e492-40e3-9bca-00ee6a46ceb6

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Now showing 1 - 6 of 6
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    Nuclear magnetic resonance detection and spectroscopy of single proteins using quantum logic
    (American Association for the Advancement of Science (AAAS), 2016) Lovchinsky, Igor; Sushkov, Alexander; Urbach, Elana; de Leon, Nathalie Pulmones; Choi, Soonwon; De Greve, Kristiaan; Evans, Ruffin; Gertner, Rona; Bersin, Eric; Muller, Christopher Michael; McGuinness, L.; Jelezko, F.; Walsworth, Ronald; Park, Hongkun; Lukin, Mikhail
    Nuclear magnetic resonance spectroscopy is a powerful tool for the structural analysis of organic compounds and biomolecules but typically requires macroscopic sample quantities. We use a sensor, which consists of two quantum bits corresponding to an electronic spin and an ancillary nuclear spin, to demonstrate room temperature magnetic resonance detection and spectroscopy of multiple nuclear species within individual ubiquitin proteins attached to the diamond surface. Using quantum logic to improve readout fidelity and a surface-treatment technique to extend the spin coherence time of shallow nitrogen-vacancy centers, we demonstrate magnetic field sensitivity sufficient to detect individual proton spins within 1 second of integration. This gain in sensitivity enables high-confidence detection of individual proteins and allows us to observe spectral features that reveal information about their chemical composition.
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    Quantum Control of Many-body Localized States
    Choi, Soonwon; Yao, N.Y.; Gopalakrishnan, Sarang; Lukin, Mikhail; Lukin, Mikhail
    We propose and analyze a new approach to the coherent control and manipulation of quantum degrees of freedom in disordered, interacting systems in the many-body localized phase. Our approach leverages a number of unique features of many-body localization: a lack of thermalization, a locally gapped spectrum, and slow dephasing. Using the technique of quantum phase estimation, we demonstrate a protocol that enables the local preparation of a many-body system into an effective eigenstate. This leads to the ability to encode information and control interactions without full microscopic knowledge of the underlying Hamiltonian. Finally, we analyze the effects of weak coupling to an external bath and provide an estimate for the fidelity of our protocol.
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    Magnetic resonance spectroscopy of an atomically thin material using a single-spin qubit
    (American Association for the Advancement of Science (AAAS), 2017) Lovchinsky, Igor; Lukin, Mikhail; Sanchez-Yamagishi, Javier; Urbach, Elana; Choi, Soonwon; Fang, Shiang; Andersen, Trond; Watanabe, Kenji; Taniguchi, Takashi; Bylinskii, Alexei; Kaxiras, Efthimios; Kim, Philip; Park, Hongkun
    Two-dimensional (2D) materials offer a promising platform for exploring condensed matter phenomena and developing technological applications. However, the reduction of material dimensions to the atomic scale poses a challenge for traditional measurement and interfacing techniques that typically couple to macroscopic observables. We demonstrate a method for probing the properties of 2D materials via nanometer-scale nuclear quadrupole resonance (NQR) spectroscopy using individual atom-like impurities in diamond. Coherent manipulation of shallow nitrogen-vacancy (NV) color centers enables the probing of nanoscale ensembles down to ∼30 nuclear spins in atomically thin hexagonal boron nitride (h-BN). The characterization of low-dimensional nanoscale materials could enable the development of new quantum hybrid systems, combining atom-like systems coherently coupled with individual atoms in 2D materials.
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    Coulomb Bound States of Strongly Interacting Photons
    (American Physical Society (APS), 2015) Maghrebi, M. F.; Gullans, M. J.; Bienias, P.; Choi, Soonwon; Martin, I.; Firstenberg, O.; Lukin, Mikhail; Büchler, H. P.; Gorshkov, A. V.
    We show that two photons coupled to Rydberg states via electromagnetically induced transparency can interact via an effective Coulomb potential. This interaction gives rise to a continuum of two-body bound states. Within the continuum, metastable bound states are distinguished in analogy with quasibound states tunneling through a potential barrier. We find multiple branches of metastable bound states whose energy spectrum is governed by the Coulomb potential, thus obtaining a photonic analogue of the hydrogen atom. Under certain conditions, the wave function resembles that of a diatomic molecule in which the two polaritons are separated by a finite “bond length.” These states propagate with a negative group velocity in the medium, allowing for a simple preparation and detection scheme, before they slowly decay to pairs of bound Rydberg atoms.
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    Quantum Convolutional Neural Networks
    (Springer Science and Business Media LLC, 2019-08-26) Cong, Iris; Choi, Soonwon; Lukin, Mikhail
    Neural network-based machine learning has recently proven successful for many complex applications ranging from image recognition to precision medicine. However, its direct application to problems in quantum physics is challenging due to the exponential complexity of many-body systems. Motivated by recent advances in realizing quantum information processors, we introduce and analyze a quantum circuit-based algorithm inspired by convolutional neural networks, a highly effective model in machine learning. Our quantum convolutional neural network (QCNN) uses only O(log(N)) variational parameters for input sizes of N qubits, allowing for its efficient training and implementation on realistic, near-term quantum devices. To explicitly illustrate its capabilities, we show that QCNN can accurately recognize quantum states associated with a 1D symmetry-protected topological phase, with performance surpassing existing approaches. We further demonstrate that QCNN can be used to devise a quantum error correction scheme optimized for a given, unknown error model that significantly outperforms known quantum codes of comparable complexity. Finally, potential experimental realizations and generalizations of QCNN are discussed.
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    Quantum Kibble–Zurek mechanism and critical dynamics on a programmable Rydberg simulator
    (Springer Nature, 2019-04) Keesling, Alexander; Omran, Ahmed; Levine, Harry; Bernien, Hannes; Pichler, Hannes; Choi, Soonwon; Samajdar, Rhine; Sachdev, Subir; Greiner, Markus; Lukin, Mikhail
    Quantum phase transitions (QPTs) involve transformations between different states of matter that are driven by quantum fluctuations. These fluctuations play a dominant role in the quantum critical region surrounding the transition point, where the dynamics are governed by the universal properties associated with the QPT. While time-dependent phenomena associated with classical, thermally driven phase transitions have been extensively studied in systems ranging from the early universe to Bose Einstein Condensates, understanding critical real-time dynamics in isolated, non-equilibrium quantum systems is an outstanding challenge. Here, we use a Rydberg atom quantum simulator with programmable interactions to study the quantum critical dynamics associated with several distinct QPTs. By studying the growth of spatial correlations while crossing the QPT, we experimentally verify the quantum Kibble-Zurek mechanism (QKZM) for an Ising-type QPT, explore scaling universality, and observe corrections beyond QKZM predictions. This approach is subsequently used to measure the critical exponents associated with chiral clock models, providing new insights into exotic systems that have not been understood previously, and opening the door for precision studies of critical phenomena, simulations of lattice gauge theories and applications to quantum optimization.