Magnon-Phonon Coupling of Synthetic Antiferromagnets in a Surface Acoustic Wave Cavity Resonator.

We used a surface acoustic wave (SAW) cavity resonator to study the coupling of acoustic magnons in a synthetic antiferromagnet (SAF) and phonons carried by SAWs. The SAF is composed of a CoFeB/Ru/CoFeB trilayer, and the scattering matrix of the SAW resonator is studied to assess the coupling. We find that the spectral line width of the SAW resonator is modulated when the frequency of the excited magnons approaches the SAW resonance frequency. Such a change in the spectral linewidth can be well reproduced using macrospin-like model calculations. From the model analyses, we estimate the magnon-phonon coupling strength to be ∼9.9 MHz at a SAW resonance frequency of 1.8 GHz: the corresponding magnomechanical cooperativity is ∼0.66. As the spectral shape hardly changes in a CoFeB single-layer reference sample, these results show that SAF provides an ideal platform to study magnon-phonon coupling in an SAW cavity resonator.

Free-access optomechanical liquid probes using a twin-microbottle resonator.

Cavity optomechanics provides high-performance sensor technology, and the scheme is also applicable to liquid samples for biological and rheological applications. However, previously reported methods using fluidic capillary channels and liquid droplets are based on fixed-by-design structures and therefore do not allow an active free access to the samples. Here, we demonstrate an alternate technique using a probe-based architecture with a twin-microbottle resonator. The probe consists of two microbottle optomechanical resonators, where one bottle (for detection) is immersed in liquid and the other bottle (for readout) is placed in air, which retains excellent detection performance through the high optical Q (~107) of the readout bottle. The scheme allows the detection of thermomechanical motion of the detection bottle as well as optomechanical drive and frequency tracking with a phase-locked loop. This technique could lead to in situ metrology at the target location in arbitrary media and could be extended to ultrasensitive biochips and rheometers.

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

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.

Frequency comb generation in a quadratic nonlinear waveguide resonator.

Enhancement of a nonlinear optical interaction through waveguides or resonators disclose unconventional interplay among multiple lights. Microresonator-based optical frequency comb (OFC) generation via third order nonlinearity is a typical example of such enhancements. Recently, quadratic-nonlinearity-based OFC with an external cavity configuration has been found and its on-chip implementation is highly demanded. Here we for the first time demonstrate such an on-chip OFC with a quadratic nonlinear waveguide resonator. Furthermore, we controlled the comb spectra separation by adjusting frequency difference of two pump light. This on-chip quadratic device will be useful for not only metrologies but also integrated quantum information technologies.

Stimulated Brillouin scattering and Brillouin-coupled four-wave-mixing in a silica microbottle resonator.

We report the first observation of stimulated Brillouin scattering (SBS) with Brillouin lasing, and Brillouin-coupled four-wave-mixing (FWM) in an ultra-high-Q silica microbottle resonator. The Brillouin lasing was observed at the frequency of ΩB = 2π × 10.4 GHz with a threshold power of 0.45 mW. Coupling between Brillouin and FWM was observed in both backward and forward scattering directions with separations of 2ΩB. At a pump power of 10 mW, FWM spacing reached to 7th and 9th order anti-Stokes and Stokes, respectively.

Distillation of photon entanglement using a plasmonic metamaterial.

Plasmonics is a rapidly emerging platform for quantum state engineering with the potential for building ultra-compact and hybrid optoelectronic devices. Recent experiments have shown that despite the presence of decoherence and loss, photon statistics and entanglement can be preserved in single plasmonic systems. This preserving ability should carry over to plasmonic metamaterials, whose properties are the result of many individual plasmonic systems acting collectively, and can be used to engineer optical states of light. Here, we report an experimental demonstration of quantum state filtering, also known as entanglement distillation, using a metamaterial. We show that the metamaterial can be used to distill highly entangled states from less entangled states. As the metamaterial can be integrated with other optical components this work opens up the intriguing possibility of incorporating plasmonic metamaterials in on-chip quantum state engineering tasks.

Analytical investigation of optical vortices emitted from a collectively polarized dipole array.

Many approaches for producing optical vortices have been developed both for fundamental interests of science and for engineering applications. In particular, the approach with direct excitation of several emitters has a potential to control the topological charges with a control of the source conditions without any modifications of structures of the system. In this paper, we investigate the propagation properties of the optical vortices emitted from a collectively polarized electric dipole array as a simple model of the several emitters. Using an analytical approach based on the Jacobi-Anger expansion, we derive a relationship between the topological charge of the optical vortices and the source conditions of the emitter, and clarify and report our new finding; there exists an intrinsic split of the singular points in the electric field due to the spin-orbit interaction of the dipole fields.

Speciation of mercury in salmon egg cell cytoplasm in relation with metallomics research.

Speciation of mercury in salmon egg cell cytoplasm was investigated by surfactant-mediated high-performance liquid chromatography/inductively coupled plasma mass spectrometry (HPLC/ICP-MS), where an ODS (octadecylsilica) column coated with a bile acid derivative, CHAPS (3-[(3-cholamidopropyl)-dimethylammonio]-1-propane sulfonate), was used for species separation. Prior to the speciation analysis, total Hg in the cell cytoplasm was determined by ICP-MS at m/z 202 in a flow injection mode. For the precise measurement, salmon egg cell cytoplasm was diluted five-fold with 0.1M Tris (Tris(hydroxymethyl)aminomethane)-HNO(3) buffer solution, and the standard addition method was employed. Thus, the total concentration of Hg in cell cytoplasm was estimated to be 12.4ngg(-1) on the wet weight basis. Next, the cell cytoplasm diluted five-fold with 0.1M Tris-HNO(3) buffer solution was analyzed by surfactant-mediated HPLC with the dual detection system of a UV absorption detector and an ICP-MS instrument. Two peaks corresponding to some proteins and small molecules were mainly observed in those chromatograms. When salmon egg cell cytoplasm was diluted five-fold with 0.01M Tris buffer solution or pure water, some precipitates appeared probably because of precipitation of hydrophobic proteins in cytoplasm. After the precipitates were eliminated with a membrane filter, the filtrate was subjected to the analysis by surfactant-mediated HPLC/UV/ICP-MS. As a result, the peaks for small molecular species of Hg were clearly observed at the retention time near 4.0min (corresponding to low-molecular weight zone) in the chromatograms with UV absorption detection as well as with Hg- and S-specific ICP-MS detections. The small molecule bound with Hg was identified as cysteine through the cysteine-spiked experiment. In addition, the protein fraction on the chromatogram obtained by using the CHAPS-coated ODS column was further analyzed by SEC (size exclusion chromatography). Consequently, several protein peaks with molecular weight of 300, 50 and 12kDa were observed in all the detections of UV absorption, Hg and Se, although two peaks among them were coincident in the case of S. These results indicate that Hg in salmon egg cell cytoplasm binds with proteins containing selenocysteine and/or cysteine residues in proteins.

Speciation of small molecules and inorganic ions in salmon egg cell cytoplasm by surfactant-mediated HPLC/ICP-MS.

The speciation of diverse elements in salmon egg cell cytoplasm was performed by a surfactant-mediated HPLC/ICP-MS hyphenated system. In the present experiment, an ODS column coated with CHAPS (3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate), which is a zwitterionic bile acid derivative, was employed as a surfactant-mediated separation column, and ICP-MS was used as an element-selective detector. The present surfactant-mediated HPLC allowed us to separate large and small molecules within 10 min; large molecules, such as proteins, were eluted within 2.5 min, while small molecules were eluted after 2.5 min, but within 10 min. In the present experiment, Fe, Cu, and Zn in egg cell cytoplasm were observed mostly in species with large molecular weights, indicating that these elements are contained as metalloproteins or metalloenzymes in egg cell cytoplasm. On the contrary, it was found that P, S, Mo, and halogens in egg cell cytoplasm were contained as small molecules or inorganic ions. The major species of P in egg cell cytoplasm was identified as the phosphate ion (PO4(3-)). Molybdenum, Cl, and Br in egg cell cytoplasm were molybdate (MoO4(2-), chloride (Cl-), and bromide (Br-) ions, respectively.