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 K04: Quantum Information Science |
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Chair: Adam Kaufman, JILA/University of Colorado Room: Wisconsin Center 102AB |
Wednesday, May 29, 2019 2:00PM - 2:12PM |
K04.00001: Strontium atom arrays: toward Rydberg entanglement and optical qubit control Ivaylo Madjarov, Jacob Covey, Alexandre Cooper, Adam Shaw, Vladimir Schkolnik, Ryan White, Jason Williams, Manuel Endres Recent work on high-fidelity and low-loss imaging of single strontium atoms has opened the door to assembly and readout of defect-free strontium arrays. We present the results of this work, as well as progress toward Rydberg-mediated entanglement. Strontium has several potential advantages for high-fidelity entanglement. One such advantage is its metastable and optically-resolved clock state, which can be used as a high-lying ground state for single-photon Rydberg excitation. We further discuss progress toward an optical qubit realized by coherent driving of the clock transition, and the potential for qubit entanglement via Rydberg dressing. [Preview Abstract] |
Wednesday, May 29, 2019 2:12PM - 2:24PM |
K04.00002: Progress towards tweezer-based assembly of many-body states of strontium in an optical lattice Aaron Young, Matthew Norcia, William Eckner, Benjamin Johnston, Adam Kaufman Microscopy of ultracold atoms trapped in optical potentials has proven to be a powerful platform for studying quantum many-body systems, with applications ranging from metrology to quantum information and simulation. So far, much of this work has centered on alkali atoms, whose internal degrees of freedom grant ease of control and detection. Here, I present tools for high-fidelity single-particle-resolved detection of the alkaline-earth atom strontium (Sr), and full quantum state control of its motional and internal degrees of freedom. These capabilities are enabled by our use of the diverse optical transitions present in Sr and other alkaline-earth atoms, key for ground-state cooling, rapid detection, and the generation of long-lived atom-optical coherence. These tools enable a variety of future directions; in this talk I will focus on our progress towards optical tweezer-based rearrangement of Sr in an optical lattice. By combining the flexible motional control and state preparation afforded by Sr in optical tweezers with the very stable potential provided by an optical lattice, we aim to study 1D and 2D Hubbard model physics in a lattice, with arbitrary initial state preparation and site- and particle-resolved readout. [Preview Abstract] |
Wednesday, May 29, 2019 2:24PM - 2:36PM |
K04.00003: Super-resolution microscopy of cold atoms in an optical lattice Jonathan Trisnadi, Mickey McDonald, Kai-Xuan Yao, Mingjiamei Zhang, Cheng Chin Super-resolution microscopy has revolutionized the fields of biology and chemistry by resolving features at the molecular level. In atomic physics, the ability to image atomic density distributions beyond the diffraction limit can play a key role in investigating lattice models with non-trivial spatial features, including Hubbard models with higher-occupied orbitals, Fermion-pairing at the BCS-BEC crossover, and atomic micromotion in Floquet lattice systems. Here we demonstrate super-resolution imaging based on the nonlinear response of atoms to spatially-varying optical pumping light. With this technique we achieve a FWHM resolution of 32(4)~nm, a localization precision below 500~pm, and a temporal resolution of 1.4~$\mu$s. A byproduct of our scheme is the emergence of large mm-scale moir\'{e} patterns, which we show to be immensely-magnified images of the single-site density distribution. Finally, we report progress on our development of a “Quantum Matter Synthesizer” which combines quantum gas microscopy with single-site addressing via optical tweezers. [Preview Abstract] |
Wednesday, May 29, 2019 2:36PM - 2:48PM |
K04.00004: Natural quantum error-correction in many-body dynamics implies stability of volume-law entangled states against projective measurements Soonwon Choi, Yimu Bao, Xiaoliang Qi, Ehud Altman In a generic isolated quantum many-body system, entanglement entropy of any subsystem grows linearly in time until saturated to a value proportional to its volume. Random projective measurements, however, can severely affect such dynamics by disentangling the measured parts from the rest of the system. In this work, we investigate this interplay between entangling dynamics and projective measurements from the perspective of quantum information theory. We show that volume-law entangled states can remain stable even when a substantial fraction of the system is measured in every time unit. Our key observation, based on the quantum decoupling theorem, is that a sufficiently scrambling unitary can hide quantum correlations in a non-local form such that local measurements cannot decrease entanglement. Such dynamics is generic and can be explicitly demonstrated in a toy model involving random local unitary gates acting on a chain of qubit clusters followed by probabilistic measurements. Our work suggests that the stability of the volume-law entangling phase originates from the effective quantum error correcting feature of scrambling dynamics, which protects quantum entanglement from the noisy environment. [Preview Abstract] |
Wednesday, May 29, 2019 2:48PM - 3:00PM |
K04.00005: Quantum Virtual Cooling Jordan Cotler, Soonwon Choi, Alexander Lukin, Hrant Gharibyan, Tarun Grover, M. Eric Tai, Matthew Rispoli, Robert Schittko, Philipp Preiss, Adam Kaufman, Markus Greiner, Hannes Pichler, Patrick Hayden We propose a quantum information based scheme to reduce the temperature of quantum many- body systems, and access regimes beyond the current capability of conventional cooling techniques. We show that collective measurements on multiple copies of a system at finite temperature can simulate measurements of the same system at a lower temperature. This idea is illustrated for the example of ultracold atoms in optical lattices, where controlled tunnel coupling and quantum gas microscopy can be naturally combined to realize the required collective measurements to access a lower, virtual temperature. Our protocol is experimentally implemented for a Bose-Hubbard model on up to 12 sites, and we successfully extract expectation values of observables at half the temperature of the physical system. Additionally, we present related techniques that enable the extraction of zero-temperature states directly. [Preview Abstract] |
Wednesday, May 29, 2019 3:00PM - 3:12PM |
K04.00006: Increasing qubit readout fidelity and efficiency with two-mode squeezed light Xi Cao, Gangqiang Liu, Tzu-Chiao Chien, Chao Zhou, Pinlei Lu, Michael Hatridge Implementing quantum information processing on a large scale with flawed components requires highly efficient, quantum non-demolition (QND) qubit readout. In superconducting circuits, qubit readout using coherent light with fidelity above 99{\%} has been achieved by using a quantum-limited parametric amplifier such as the Josephson Parametric Converter (JPC), as the first stage amplifier. However, further improvement of such measurement is fundamentally limited by the vacuum fluctuations on the ports of the JPC. Alternatively, readout with squeezed input can entangle the vacuum fluctuations in different modes, thus allowing for the reduction of the noise by controlling their interference. In this talk, we demonstrate a dispersive qubit readout scheme which exploits the two-mode squeezed light generated by a first JPC and processed by a second JPC to form an amplified interferometer [1]. We have observed a 20{\%} improvement in the voltage Signal-to-Noise Ratio (SNR) of the measurement compared to coherent light. We can extend this scheme to generate remote entanglement by placing a qubit-cavity in each arm of the interferometer. We will discuss how the role of losses changes in this system for coherent vs two squeezed light. [1] Sh. Barzanjeh et al, PRB 90, 134515 (2014). [Preview Abstract] |
Wednesday, May 29, 2019 3:12PM - 3:24PM |
K04.00007: Topological bands and triply-degenerate points in non-Hermitian hyperbolic metamaterials Junpeng Hou, Zhitong Li, Xi-Wang Luo, Qing Gu, Chuanwei Zhang Hyperbolic metamaterials (HMMs), an unusual class of electromagnetic metamaterials, have found important applications in various fields due to their distinctive properties. A surprising feature of HHMs found recently is that even continuous HMMs can possess topological edge modes. However, previous studies based on equal-frequency surface (analogy of Fermi surface) may not correctly capture the topology of entire bands. Here we develop a topological band description for continuous HMMs that can be described by a non-Hermitian Hamiltonian formulated from Maxwell's equations. We find two types of three dimensional photonic triply-degenerate points with topological charges $\pm 2$ and 0 induced by chiral and gyromagnetic effects that break spatial inversion and time-reversal symmetries, respectively. Because of the photonic nature, the vacuum band plays an important role for topological edge states and bulk-edge correspondence in HMMs. The topological band results are numerically confirmed by direct simulation of Maxwell's equations. Our work presents a general non-Hermitian topological band treatment of continuous HMMs, paving the way for exploring interesting topological phases in photonic continua. [Preview Abstract] |
Wednesday, May 29, 2019 3:24PM - 3:36PM |
K04.00008: Cascaded collimator for atomic beams traveling in planar silicon devices Chao Li, Xiao Chai, Bochao Wei, Jeremy Yang, Anosh Daruwalla, Farrokh Ayazi, Chandra Raman We present a microfabricated planar device for thermal atomic beams production. Etched microchannels were used to create highly collimated, continuous rubidium atom beams traveling parallel to a silicon wafer surface. Precise, lithographic definition of the guiding channels allowed for shaping and tailoring the velocity distributions in entirely novel ways not possible using conventional machining. Multiple miniature beams with individually prescribed geometries were created, including collimated, focusing and diverging outputs. A new, ``cascaded'', multi-stage collimator was realized through a sequence of self-aligned micro capillaries. Doppler sensitive fluorescence spectroscopy, Monte Carlo and master equation simulations were performed to understand the performance of the cascaded collimator. We conclude that such cascaded design achieves 40 times better suppression of off-axis atoms emitted into large angles than conventional collimators, without deteriorating the on-axis beam brightness at all. A patent is pending (U.S. Patent Application No. 62/672,709). [Preview Abstract] |
Wednesday, May 29, 2019 3:36PM - 3:48PM |
K04.00009: Quantum Transport of Rydberg Excitation with Synthetic Spin-Exchange Interactions Fan Yang, Shuo Yang, Li You Coherent transfer of quantum state in a many-body system is indispensable for quantum information processing. In this work, a simple scheme is proposed for engineering quantum transport dynamics of spin excitations in a chain of laser-dressed Rydberg atoms. The transport occurs due to a synthetic spin exchange arising from diagonal van der Waals interaction. For a single Rydberg exciton, we show that deterministic entanglement between distant atoms can be established by tuning local dressing parameters. Furthermore, the topological exciton pumping can be realized by dynamically modulating dressing fields, which facilitates quantized entanglement transfer. For multi-excitons, we show that long-range exciton-exciton interaction permits the formation of high-order magnon bound state, which exhibits nonlocal correlated transport even when dephasing dominates over its center of mass motion. Different from previous schemes discussed, our proposal requires neither resonant dipole-dipole interaction nor off-diagonal van der Waals interaction, and thus avoids the complicated excitation schemes encountered in multi-Rydberg-level systems. [Preview Abstract] |
Wednesday, May 29, 2019 3:48PM - 4:00PM |
K04.00010: Integrated multi-wavelength photonic addressing of trapped ion qubits Robert Niffenegger, Jules Stuart, Colin Bruzewicz, Robert McConnell, Gavin West, Garrett Simon, Dave Kharas, Cheryl Sorace-Agaskar, Suraj Bramhavar, Jeremy Sage, John Chiaverini Integrating quantum and classical technologies with systems like trapped ions is critical to enable the Moore's law like scaling of qubits necessary to develop practical quantum computers. For instance, individual addressing of trapped ion qubits typically requires bulky free space optics to tightly focus multiple laser beams onto single ions within linear chains, limiting scalability. Here we have designed and fabricated an ion trap chip with integrated photonic waveguides and grating out-couplers for integrated addressing in all of the infrared, visible, and ultraviolet wavelengths required to cool and control~$^{\mathrm{88}}$Sr$+$ trapped ion qubits. The combination of recently developed low loss UV photonic waveguides made from Al$_{\mathrm{2}}$O$_{\mathrm{3}}$ with more typical SiN waveguides for IR and visible wavelengths within multiple layers of the chip enables integration of light at all the wavelengths required for ion control. We study the interaction of these new multi-wavelength photonics with a single ion qubit towards demonstration of a two qubit gate controlled via integrated technologies, a key component of a scalable trapped ion quantum information processor. [Preview Abstract] |
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