Bulletin of the American Physical Society
APS March Meeting 2021
Volume 66, Number 1
Monday–Friday, March 15–19, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session Y27: Hybrid/Macroscopic Quantum Systems, Optomechanics, and Interfacing AMO with Solid State/Nano Systems IILive
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Sponsoring Units: DAMOP DQI Chair: Dalziel Wilson, University of Arizona |
Friday, March 19, 2021 11:30AM - 11:42AM Live |
Y27.00001: Topological phonon transport in an optomechanical system Hengjiang Ren, Tirth Shah, Hannes Pfeifer, Christian Brendel, Vittorio Peano, Florian Marquardt, Oskar Painter Recent advances in cavity-optomechanics have now made it possible to use light to measure mechanical motion down to the individual phonons. At the same time, microfabrication techniques have enabled small-scale on-chip optomechanical circuits. Motivated by these developments, several theoretical works have envisioned larger scale optomechanical systems where light is used to steer and detect on-chip topological vibrations. We present the observation of topological phonon transport within a multiscale optomechanical crystal structure consisting of an array of over 800 cavity-optomechanical elements. Using sensitive, spatially resolved optical read-out, we detect thermal phonons in a 0.325−0.34 GHz band traveling along a topological edge channel, with substantial reduction in backscattering. This work further advances the ongoing effort to miniaturize topological phononic devices down to the nanoscale, opening the way to GHz frequency acoustic wave circuits comprising robust delay lines and non-reciprocal elements. |
Friday, March 19, 2021 11:42AM - 11:54AM Live |
Y27.00002: Ground state cooling of a radio-frequency LC circuit in an optoelectromechanical system Nicola Malossi, Paolo Piergentili, Jie Li, Enrico Serra, Riccardo Natali, Giovanni Di Giuseppe, David Vitali We present a complete theory for laser cooling of a macroscopic radio-frequency LC electrical circuit by means of an optoelectromechanical system, consisting of an optical cavity dispersively coupled to a nanomechanical oscillator, which is in turn capacitively coupled to the LC circuit of interest. We determine the optimal parameter regime where the LC resonator can be cooled down to its quantum ground state, which requires a large optomechanical cooperativity, and a larger electromechanical cooperativity. Moreover, comparable optomechanical and electromechanical coupling rates are preferable for reaching the quantum ground state. |
Friday, March 19, 2021 11:54AM - 12:06PM Live |
Y27.00003: Hierarchical tensile structures with ultralow dissipation Nils Johan Engelsen, Robin Groth, Alberto Beccari, Mohammadjafar Bereyhi, Sergey Fedorov, Tobias J. Kippenberg Self-similar structures occur naturally and have been employed to engineer exotic physical properties. We report nanofabricated resonators with exceptionally low mechanical dissipation rates enabled by an unconventional type of “soft-clamping" which emerges in branched systems of tensioned strings. We fabricate self-similar binary trees of high-stress Si3N4 with fundamental mode quality factors as high as 500 million at 150 kHz mode frequencies, corresponding to thermal-noise-limited force sensitivities below 1 aN/rtHz. Intriguingly, the hierarchical organization of branches in binary tree resonators results in high-order acoustic mode densities consistent with non-integer spectral dimensions, characteristic of fractal geometries. Finally, exploiting the same design principles we create trampoline membranes with quality factors up to 250 million at 100 kHz mode frequencies. Our results open new avenues in nanoscale sensing and quantum experiments with mechanical resonators. |
Friday, March 19, 2021 12:06PM - 12:18PM Live |
Y27.00004: Large Quantum Delocalization of a Levitated Nanoparticle using Optimal Control: Applications for Force Sensing and Entangling via Weak Forces Marc Roda-Llordes, Talitha Weiss, Erik Torrontegui, Oriol Romero-Isart We propose to optimally control the harmonic potential of a levitated nanoparticle to quantum delocalize its center-of-mass motional state to a length scale orders of magnitude larger than the quantum zero-point motion. Using a bang-bang control of the harmonic potential, including the possibility to invert it, the initial ground-state-cooled levitated nanoparticle coherently expands to large scales and then contracts to the initial state in a time-optimal way. We show that this fast loop protocol can be used to enhance force sensing as well as to dramatically boost the entangling rate of two weakly interacting nanoparticles. We parameterize the performance of the protocol, and therefore the macroscopic quantum regime that could be explored, as a function of displacement and frequency noise in the nanoparticle. This noise analysis accounts for the sources of decoherence relevant to current experiments. |
Friday, March 19, 2021 12:18PM - 12:30PM Live |
Y27.00005: Levitation of a permanent magnet within a superconducting radio frequency cavity Nabin Raut, Jeffery Miller, Jacob M Pate, Raymond Y Chiao, Jay Sharping We report on the magnetic levitation of millimeter-sized neodymium permanent magnets within the interior of a superconducting radio frequency (SRF) cavity. To the best of our knowledge, this is the first experimental work on levitating a magnet within an SRF cavity. The cavity is a coaxial quarter-wave microwave resonator made from 6061 aluminum, having a resonance frequency of 10 GHz and a loaded Q of about 2,000. The 3 disc magnets have identical dimensions of 0.5-mm high, 1-mm diameter, and 3.75-mg mass. We performed a sequence of experiments, below the 1.2-K superconducting transition temperature of aluminum, where only the magnetic field strength changes, while the size, shape and mass of the magnet are held constant . For this purpose, the magnets of remanence (maximum magnetic field) 1.22T, 1.32T, 1.44T, 1.47T is used. The coaxial mode's resonance frequency shifts as a function of the levitation height of the magnet, giving an estimate of the magnet’s position, and mechanical motion. Both the levitation height and levitation temperature are found to increase with increasing magnetic field. The measurements are consistent over several heating and cooling cycles. |
Friday, March 19, 2021 12:30PM - 12:42PM Live |
Y27.00006: Magnetic interfaces between spin waves and nitrogen-vacancy centers Carlos Gonzalez-Ballestero, Toeno van der Sar, Oriol Romero-Isart Spin waves are promising information carriers in next-generation computers. Interfacing them with quantum emitters could enable to tailor their properties in analogy with the modifications of light propagation in dense atomic media. |
Friday, March 19, 2021 12:42PM - 12:54PM Live |
Y27.00007: Magnon-exciton proximity coupling at a van der Waals heterointerface Arnaud Gloppe, Masaru Onga, Ryusuke Hisatomi, Atac Imamoglu, Yasunobu Nakamura, Yoshihiro Iwasa, Koji Usami Spin and photonic systems are at the heart of modern information devices and emerging quantum technologies. An interplay between electron-hole pairs (excitons) in semiconductors and collective spin excitations (magnons) in magnetic crystals would bridge these heterogeneous systems, leveraging their individual assets in novel interconnected devices. We report the magnon-exciton coupling at the interface between a magnetic thin film and an atomically-thin semiconductor. Our approach allies the exceptionally long-lived magnons hosted in a film of yttrium iron garnet (YIG) to strongly-bound excitons in a flake of a transition metal dichalcogenide, MoSe2. The magnons induce on the excitons a dynamical valley Zeeman effect ruled by interfacial exchange interactions. This nascent class of hybrid system suggests new opportunities for information transduction between microwave and optical regions. |
Friday, March 19, 2021 12:54PM - 1:06PM Live |
Y27.00008: Measurements of High-Order Phonon Correlations in an Optomechanical System via Single-Photon Detection Jiaxin Yu, Yogesh S S Patil, Sean Frazier, Yiqi Wang, Jared R Fox, Sébastien Garcia, Konstantin Ott, Jakob Reichel, Jack G E Harris We have used photon-counting techniques to probe and control the state of an acoustic mode having an effective mass of 6 ng. The acoustic mode resides in a body of superfluid helium which is confined inside a fiber-optic cavity. When a laser excites this cavity, every Stokes- and anti-Stokes sideband photon heralds the production (or annihilation) of an individual phonon from the acoustic mode. We record the arrival times of the sideband photons and use the correlations in this data to measure the phonon coherences up to the fourth order. These measurements agree well with theoretical predictions that assume the acoustic mode is in a thermal state. By post-selecting the data, we also measure the phonon coherences (up to third order) of phonon-subtracted/added thermal states, as well as the dynamics of their mean phonon occupancy. We discuss how such coherences can in principle be used to reconstruct the phonon-added thermal state's Wigner function. Lastly, we will describe how these measurements benefit from this device's design, which offers truly single-mode optomechanical coupling, and removes the need for an in situ alignment. |
Friday, March 19, 2021 1:06PM - 1:18PM Live |
Y27.00009: Measurement of Non-classical Photon-Phonon States in a Superfluid Optomechanical System Yiqi Wang, Yogesh S S Patil, Jiaxin Yu, Sean Frazier, Jared R Fox, Sébastien Garcia, Konstantin Ott, Jakob Reichel, Jack G E Harris Non-classical states with a negative Glauber-Sudarshan P-function can offer metrological advantages and can outperform sensitivity bounds associated with coherent states [1]. They also play an important role in quantum communication, quantum sensing, and fundamental tests of quantum mechanics. Here, we demonstrate the creation and observation of non-classical photon-phonon states using an optomechanical device that consists of a fiber cavity filled with superfluid helium [2]. We use photon-counting techniques to demonstrate the violation of a classical bound on photon-phonon correlations that is set by the Cauchy-Schwarz inequality, thereby revealing the state's P-function negativity [3,4]. We find that the non-classical correlations decay with a time constant of ~50us, which is set by the phonon mode lifetime. With an effective mass ~6 ng, this system is one of the most massive objects to demonstrate P-function negativity. |
Friday, March 19, 2021 1:18PM - 1:30PM Live |
Y27.00010: Measurement of the Eigenvalue Braiding in the Vicinity of a Triple Exceptional Point Yogesh S S Patil, Judith Hoeller, Parker A Henry, Chitres Guria, Yiming Zhang, Luyao Jiang, Nenad Kralj, Nicholas Read, Jack G E Harris When a non-Hermitian system's dynamical matrix (or "Hamiltonian") is tuned around a closed loop in the vicinity of an exceptional point (ΕΡ), the system's complex eigenvalues trace out a braid. We have realized such eigenvalue braiding in a three-mode mechanical system by using cavity optomechanical techniques to tune the Hamiltonian of three vibrational modes in a SiN membrane. By measuring the modes' complex eigenvalues we show that the system can be tuned to a triple exceptional point (ΕΡ3), and that the eigenvalues exhibit the expected behavior in the vicinity of this ΕΡ3. Specifically, we show that varying the Hamiltonian in closed loops results in eigenvalue braids that correspond to the generators of the braid group Β3. We also show that for any given loop, the specific braid which it produces is determined by how that loop encloses the set of double degeneracies (i.e., ΕΡ2's). This highlights the central role played by ΕΡ2's in determining the eigenvalue topology, even in systems with more than two modes. In the following talk, we describe measurements of the locations of the ΕΡ2's in the neighborhood of the ΕΡ3, and show that they form a trefoil knot. |
Friday, March 19, 2021 1:30PM - 1:42PM Live |
Y27.00011: Measuring the Trefoil Knot of Degneracies Around a Triple Exceptional Point Parker A Henry, Yogesh S S Patil, Judith Hoeller, Chitres Guria, Yiming Zhang, Luyao Jiang, Nenad Kralj, Nicholas Read, Jack G E Harris When a non-Hermitian system's Ν×Ν dynamical matrix (or "Hamiltonian") is tuned around a loop that does not intersect any degeneracies, the system's Ν complex eigenvalues trace out a braid. We show that the specific braid produced by a given loop is determined by how that loop encloses the system's double degeneracies (ΕΡ2's). We have measured the eigenvalue spectra of a three-mode mechanical system (which is tuned via standard optomechanical techniques), and show that the system's triple degeneracy point (ΕΡ3) is surrounded by a knotted structure of ΕΡ2's. This structure is closely related to the well-known trefoil knot. These measurements (and the measurements of eigenvalue braids presented in the preceding talk) agree well with calculations based on this specific device's optomechanical properties. More importantly, this work illustrates how concepts from algebraic geometry (e.g., knots and braids) can play a useful role in understanding the eigenvalue topology of non-Hermitian systems. |
Friday, March 19, 2021 1:42PM - 1:54PM Live |
Y27.00012: Imaging and localizing individual atoms interfaced with a nanophotonic waveguide Yijian Meng, Christian Liedl, Sebastian Pucher, Arno Rauschenbeutel, Philipp Schneeweiss Single particle-resolved fluorescence imaging is an enabling technology in cold-atom physics. However, so far, this technique was not available for nanophotonic atom--light interfaces. Here, we image single atoms that are trapped and optically interfaced using an optical nanofiber. Near-resonant light is scattered off the atoms and imaged while counteracting heating mechanisms via degenerate Raman cooling. We detect trapped atoms within 150 ms and record image sequences of given atoms. Building on our technique, we perform two experiments which are conditioned on the number and position of the nanofiber-trapped atoms. We measure the transmission of nanofiber-guided resonant light and verify its exponential scaling in the few-atom limit, in accordance with Beer-Lambert's law. Moreover, depending on the interatomic distance, we observe interference of the fields that two simultaneously trapped atoms emit into the nanofiber. The demonstrated technique enables post-selection and possible feedback schemes and thereby opens the road towards a new generation of experiments in quantum nanophotonics. |
Friday, March 19, 2021 1:54PM - 2:06PM Live |
Y27.00013: Mediating dipole-dipole-interactions using three-dimensional atomic arrays Katharina Brechtelsbauer, Daniel Malz Nanophotonic structures are widely employed to engineer the bandstructure of light and thus provide a way to tune the interactions between quantum emitters in their vicinity. To date, mostly solid-state nanophotonic structures have been explored. |
Friday, March 19, 2021 2:06PM - 2:18PM Live |
Y27.00014: Strong Coupling of a Single Trapped Atom to a Whispering-Gallery-Mode Microresonator Elisa Will, Luke Masters, Arno Rauschenbeutel, Michael Scheucher, Jürgen Volz The interaction between an atom and photons can be strongly enhanced by coupling the atom to an optical microresonator with high quality factor. Whispering-gallery-mode (WGM) resonators are particularly interesting for this purpose, as they offer chiral, i.e. propagation-direction-dependent, light-matter interaction [1], which enables novel protocols for processing light on the quantum level. However, coupling trapped atoms to WGM resonators has so far been an elusive goal. |
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