Showing papers by "Hiroshi Yamaguchi published in 2020"

Mechanical Kerr Nonlinearity of Wave Propagation in an On-Chip Nanoelectromechanical Waveguide

Abstract: We experimentally and numerically demonstrate nonlinear flexural wave propagation using an on-chip nanoelectromechanical waveguide. More specifically, third-order nonlinear phenomena of self-phase modulation, cross-phase modulation, and four-wave mixing caused by the mechanical Kerr effect are realized. Our experimental observations are correctly described by the nonlinear Schr\"odinger equation. The nanomechanical and integratable platform enables on-chip manipulation of mechanical wave propagation, thus offering the potential to develop novel functional devices and study nonlinear mechanical phenomena.

Demonstration of Multiple Internal Resonances in a Microelectromechanical Self-Sustained Oscillator

Abstract: We investigate the dynamics of a microelectromechanical self-sustained oscillator supporting multiple resonating and interacting modes. In particular, the interaction of the first four flexural modes along with the first torsional mode are studied, whereby 1:2, 1:3, and 2:1 internal resonances occur. Even and odd modes are induced to couple by breaking the longitudinal symmetry of the structure. Self-oscillations are induced in the second flexural mode via a gain-feedback loop; thereafter its frequency is pulled into a commensurate frequency ratio with the other modes, enabling the oscillator to act as a driver or pump for four modes simultaneously.

Generic Rotating-Frame-Based Approach to Chaos Generation in Nonlinear Micro- and Nanoelectromechanical System Resonators.

Abstract: This Letter provides a low-power method for chaos generation that is generally applicable to nonlinear micro- and nanoelectromechanical systems (MNEMS) resonators. The approach taken is independent of the material, scale, design, and actuation of the device in question; it simply assumes a good quality factor and a Duffing type nonlinearity, features that are commonplace to MNEMS resonators. The approach models the rotating-frame dynamics to analytically constrain the parameter space required for chaos generation. By leveraging these common properties of MNEMS devices, a period-doubling route to chaos is generated using smaller forcing than typically reported in the literature.

Real-Space Characterization of Cavity-Coupled Waveguide Systems in Hypersonic Phononic Crystals

Abstract: A phononic crystal formed in a suspended membrane provides full confinement of hypersonic waves and thus realizes a range of chip-scale manipulations. In this paper, we demonstrate mode-resolved real-space characterization of mechanical-vibration properties in cavities and waveguide systems. Multiple resonant modes in various designed cavities are independently characterized, and wavelength-scale high-$Q$ resonances up to $Q=4200$ under atmospheric conditions are confirmed. This also reveals that the waveguide allows us to observe mode-resolved wave transmission and thereby drive evanescently coupled cavities. The methods offer a significant tool with which to build compact and low-power microwave phononic circuitry for applications to signal processing and hybrid quantum systems.

Radiation hardness study for the COMET Phase-I electronics

Abstract: Radiation damage on front-end readout and trigger electronics is an important issue in the COMET Phase-I experiment at J-PARC, which plans to search for the neutrinoless transition of a muon to an electron. To produce an intense muon beam, a high-power proton beam impinges on a graphite target, resulting in a high-radiation environment. We require radiation tolerance to a total dose of 1 . 0 kGy and 1 MeV equivalent neutron fluence of 1 . 0 × 10 12 neq cm − 2 including a safety factor of 5 over the duration of the physics measurement. The use of commercially-available electronics components which have high radiation tolerance, if such components can be secured, is desirable in such an environment. The radiation hardness of commercial electronic components has been evaluated in gamma-ray and neutron irradiation tests. As results of these tests, voltage regulators, ADCs, DACs, and several other components were found to have enough tolerance to both gamma-ray and neutron irradiation at the level we require.

Near-field cavity optomechanical coupling in a compound semiconductor nanowire

Abstract: A III-V compound semiconductor nanowire is an attractive material for a novel hybrid quantum interface that interconnects photons, electrons, and phonons through a wavelength-tunable quantum structure embedded in its free-standing structure. In such a nanomechanical element, however, a challenge is how to detect and manipulate a small number of phonons via its tiny mechanical motion. A solution would be to couple an optical cavity to a nanowire by introducing the ‘cavity optomechanics' framework, but the typical size difference between them becomes a barrier to achieving this. Here, we demonstrate near-field coupling of a silica microsphere cavity and an epitaxially grown InP/InAs free-standing nanowire. The evanescent optomechanical coupling enables not only fine probing of the nanowire’s mechanical motion by balanced homodyne interferometry but also tuning of the resonance frequency, linewidth, Duffing nonlinearity, and vibration axis in it. Combining this cavity optomechanics with epitaxial nanowire engineering opens the way to novel quantum metrology and information processing. Coupling submicrometer mechanical elements such as nanowires to optical cavities is technically challenging because of the size difference between the resonators. Here, the authors demonstrate cavity optomechanical coupling of a nanowire mechanical resonator to an optical microsphere through near-field evanescent gradient forces and fine-tuning of resonance properties.

Novel Fabrication Technique of Suspended Nanowire Devices for Nanomechanical Applications

Abstract: Nanomechanical devices fabricated from semiconductor nanowire are expected to be used in various applications such as many kinds of sensors and also the study of fundamental physics such like macroscopic quantum phenomena. We made such devices of InAs nanowire by developing a novel fabrication method by using inkjet printing for precise assembling of nanowire-dispersed droplets and by forming a PMGI sacrificial layer for suspending nanowire. This method allows the fabrication of highly sophisticated structures such like the quantum dot coupled with a nanomechanical system. We measured mechanical property in this device by using RF mixing technique and observed mechanical resonance around 12.8MHz with the quality factor of 750 at room temperature. This resonance showed duffing nonlinearity when we applied higher AC gate voltage to actuate vibration of nanowire. We observed not only mechanical property but also UCF (universal conductance fluctuation) in the low temperature transport measurement, which is the specific characteristics of one dimensional material, in another device similarly fabricated using the same method. As already reported in the top-down structures, the one-dimensional magnetoresistance can be used for sensitively detecting nanowire vibration and pave the way to realize highly functional quantum hybrid devices of mechanical motion and quantum carrier transport.

Gigabit Ethernet Daisy-Chain on FPGA for COMET Read-out Electronics

Abstract: The COMET experiment at J-PARC aims to search for the neutrinoless transition of a muon to an electron. We have developed the readout electronics board called ROESTI for the COMET straw tube tracker. We plan to install the ROESTI in the gas manifold of the detector. The number of vacuum feedthroughs needs to be reduced due to space constraints and cost limitations. In order to decrease the number of vacuum feedthroughs drastically, we developed a network processor with a daisy-chain function of Gigabit Ethernet for the FPGA on the ROESTI. We implemented two SiTCPs, which are hardware-based TCP processors for Gigabit Ethernet, in the network processor. We also added the data path controllers which handle the Ethernet frames and the event data. The network processor enables ROESTI to process the slow control over UDP/IP and to transfer event data over TCP/IP. By using the network processor, we measured the throughput, the stability, and the data loss rate for two to six ROESTIs. In any number of boards, the throughput of the event data transfer achieved the theoretical limit of TCP over the Gigabit Ethernet stably and ROESTI stably sent 100% of the data.

Random bit string generator

Abstract: The present invention comprises: a vibration unit (101), a measurement unit (102) and a bit generation unit (103). The measurement unit (102) measures, in time series, the vibration (thermal vibration, for example) of a set frequency generated by the vibration unit (101) for each set time. The bit generation unit (103) generates a bit string by allocating either a 0 or 1 bit to each of the sine component and cosine component of vibrations measured by the measurement unit (102).

Near-field cavity optomechanical coupling in a compound semiconductor nanowire

Abstract: A III-V compound semiconductor nanowire is an attractive material for a novel hybrid quantum interface that interconnects photons, electrons, and phonons through a wavelength-tunable quantum structure embedded in its free-standing structure In such a nanomechanical element, however, a challenge is how to detect and manipulate a small number of phonons via its tiny mechanical motion A solution would be to couple an optical cavity to a nanowire by introducing the ``cavity optomechanics'' framework, but the typical size difference between them becomes a barrier to achieving this Here, we demonstrate near-field coupling of a silica microsphere cavity and an epitaxially grown InP/InAs free-standing nanowire The evanescent optomechanical coupling enables not only fine probing of the mechanical motion by balanced homodyne interferometry but also tuning of the resonance frequency, linewidth, Duffing nonlinearity, and vibration axis in the nanowire Combining this cavity optomechanics with epitaxial nanowire engineering opens the way to novel quantum metrology and information processing