Nanomechanical Vibrations Research Articles

Imaging Nanomechanical Vibrations and Manipulating Parametric Mode Coupling via Scanning Microwave Microscopy.

In this study, we present a novel platform based on scanning microwave microscopy for manipulating and detecting tiny vibrations of nanoelectromechanical resonators using a single metallic tip. The tip is placed on the top of a grounded silicon nitride membrane, acting as a movable top gate of the coupled resonator. We demonstrate its ability to map mechanical modes and investigate mechanical damping effects in a capacitive coupling scheme, based on its spatial resolution. We also manipulate the energy transfer coherently between the mode of the scanning tip and the underlying silicon nitride membrane, via parametric coupling. Typical features of optomechanics, such as anti-damping and electromechanically induced transparency, have been observed. Since the microwave optomechanical technology is fully compatible with quantum electronics and very low temperature conditions, it should provide a powerful tool for studying phonon tunnelling between two spatially separated vibrating elements, which could potentially be applied to quantum sensing.

Nanomechanical collective vibration of SARS-CoV-2 spike proteins.

The development of effective therapeutics against COVID-19 requires a thorough understanding of the receptor recognition mechanism of the SARS-CoV-2 spike (S) protein. Here the multidomain collective dynamics on the trimer of the spike protein has been analyzed using normal mode analysis (NMA). A common nanomechanical profile was identified in the spike proteins of SARS-CoV-2 and its variants. The profile involves collective vibrations of the receptor-binding domain (RBD) and the N-terminal domain (NTD), which may mediate the physical interaction process. Quantitative analysis of the collective modes suggests a nanomechanical property involving large-scale conformational changes, which explains the difference in receptor binding affinity among different variants. These results support the use of intrinsic global dynamics as a valuable perspective for studying the allosteric and functional mechanisms of the S protein. This approach also provides a low-cost theoretical toolkit for screening potential pathogenic mutations and drug targets.

Broad‐range, high‐linearity, and fast‐response pressure sensing enabled by nanomechanical resonators based on 2D non‐layered material: β‐In2S3

AbstractTwo‐dimensional (2D) non‐layered materials, along with their unique surface properties, offer intriguing prospects for sensing applications. Introducing mechanical degrees of freedom is expected to enrich the sensing performances of 2D non‐layered devices, such as high frequency, high tunability, and large dynamic range, which could lead to new types of high performance nanosensors. Here, we demonstrate 2D non‐layered nanomechanical resonant sensors based on β‐In2S3, where the devices exhibit robust nanomechanical vibrations up to the very high frequency (VHF) band. We show that such device can operate as pressure sensor with broad range (from 10−3 Torr to atmospheric pressure), high linearity (with a nonlinearity factor as low as 0.0071), and fast response (with an intrinsic response time less than 1 μs). We further unveil the frequency scaling law in these β‐In2S3 nanomechanical sensors and successfully extract both the Young's modulus and pretension for the crystal. Our work paves the way towards future wafer‐scale design and integrated sensors based on 2D non‐layered materials.image

Graphene nanomechanical vibrations measured with a phase-coherent software-defined radio

Software-defined radios (SDRs) are radio frequency transceivers designed to facilitate digital signal processing through the use of vast libraries of open-source software. Here, we assemble a simple data acquisition system whose architecture, based on SDR, allows us to develop a comprehensive suite of tools to study the vibrations of a few-layer graphene nanomechanical resonator. Namely, we measure the cross-spectrum of vibrations in the frequency domain, we measure their energy decay rate in the time domain, we perform vector measurements of their in-phase and quadrature components, and we control their phase using a time-dependent strain field –all with a single measurement platform. Our approach allows us to tailor our experiments at will and gives us control over every stage of data processing. Overall, our versatile system enables measuring a wide range of nanomechanical properties of graphene by customizing the signal acquisition and replacing some analog electrical circuits, such as filters, mixers, and demodulators, by blocks of code.

Proposal for composite quantum electromagnetically induced transparency heat engine coupled by a nanomechanical mirror

Abstract This paper introduces a quantum heat engine model that utilizes an ultracold atomic gas coupled with a nanomechanical mirror. The mirror’s vibration induces an opto-mechanical sideband in the control field, affecting the behavior of the cold gas and subsequently influencing the output radiation of the engine. The model incorporates mirror vibration while omitting cavity confinement, establishing a bridge between a multi-level atom–laser interacting system that plays with coherences and the mechanical vibration of the nanomechanical mirror, which jointly function as heat engines. Three distinct heat engine configurations are proposed: the first involves a vibration-free three-level Λ-type system, the second introduces nanomechanical vibration to the three-level Λ-type system, and the third constitutes a composite engine that combines the previous setups along with nanomechanical vibration. The spectral brightness of a three-level heat engine is diminished with mirror vibration, whereas for a composite heat engine, there is a slight enhancement in the brightness peak. However, the maximum brightness is attained when there is no vibration. Comparisons between the proposed model and an ideal system are made regarding entropy balance, adhering to the constraints of the second law of thermodynamics. The model observed that when subjected to mirror vibration, the proposed heat engines diverged from the characteristics expected in an ideal heat engine.

Nanomechanical vibrational response from electrical mixing measurements

Driven nanomechanical resonators based on low-dimensional materials are routinely and efficiently detected with electrical mixing measurements. However, the measured signal is a non-trivial combination of the mechanical eigenmode displacement and an electrical contribution, which makes the extraction of the driven mechanical response challenging. Here, we report a simple yet reliable method to extract solely the driven mechanical vibrations by eliminating the contribution of pure electrical origin. This enables us to measure the spectral mechanical response as well as the driven quadratures of motion. This method is crucial for nanomechanical vibrations in the nonlinear regime, since the shape of the mechanical response depends on the physics at work. We further show how to calibrate the measured signal into units of displacement. Our method marks a key step forward in the study of nanoelectromechanical resonators based on low-dimensional materials in the nonlinear regime.

A microwave scattering spectral method to detect the nanomechanical vibrations embedded in a superconducting qubit

Nanomechanical resonators (NMRs), as the quantum mechanical sensing probers, have played the important roles for various high-precision quantum measurements. Differing from the previous emission spectral probes (i.e., the NMR modified the atomic emission), in this paper we propose an alternative approach, i.e., by probing the scattering spectra of the quantum mechanical prober coupled to the driving microwaves, to characterize the physical features of the NMR embedded in a rf-SQUID based superconducting qubit. It is shown that, from the observed specifical frequency points in the spectra, i.e., either the dips or the peaks, the vibrational features (i.e., they are classical vibration or quantum mechanical one) and the physical parameters (typically such as the vibrational frequency and displacements) of the NMR can be determined effectively. The proposal is feasible with the current technique and should be useful to design the desired NMRs for various quantum metrological applications.

Electrically Tunable MXene Nanomechanical Resonators Vibrating at Very High Frequencies

As an emerging class of two-dimensional (2D) layered nanomaterial, MXene exhibits a number of intriguing properties, such as good electrical conductivity and high elastic modulus, and has witnessed continued growth in related device research. However, nanoscale MXene devices which leverage both the intrinsic electrical and mechanical properties of these 2D crystals have not been experimentally studied. Here we demonstrate nanoelectromechanical resonators based on 2D MXene crystals, where Ti3C2Tx drumheads with a wide range of thickness, from more than 50 layers all the way down to a monolayer, exhibit robust nanomechanical vibrations with fundamental-mode frequency f0 up to >70 MHz in the very high frequency (VHF) band, a displacement noise density down to 52 fm/Hz1/2, and a fundamental-mode frequency-quality factor product up to f0 × Q ≈ 6.85 × 109 Hz. By combining experimental results with theoretical calculations, we independently derive the Young's modulus of 2D Ti3C2Tx crystals to be 270-360 GPa, in excellent agreement with nanoindentation measurements, based on which we elucidate frequency scaling pathways toward microwave frequencies. We further demonstrate electrical tuning of resonance frequency in MXene resonators and frequency-shift-based MXene vacuum gauges with responsivity of 736%/Torr and detection range down to 10-4 Torr. Our study can lead to the design and creation of nanoscale vibratory devices that exploit the intrinsic electrical and mechanical properties in 2D MXene crystals.

Pumping and Cooling of Nanomechanical Vibrations Generated by Cooper-Pair Exchange

We consider a nanoelectromechanical system composed of a carbon nanotube suspended between two normal leads and coupled to a superconducting scanning tunneling microscope (STM) tip via vacuum tunnel barrier. Treating the nanotube as a single-level quantum dot, it is shown that an applied voltage between the superconducting STM tip and normal leads gives rise to a pumping or a cooling of the mechanical subsystem depending on the direction of the electronic flow. It is also demonstrated that the transition between these two regimes is controlled by the strength of the tunnel coupling between the nanotube and superconducting STM tip and the relative position of the electronic level. Such phenomena are realized due to a specific electromechanical coupling that is fully governed by the quantum dynamics of the Cooper pairs. The amplitude of the self-sustained oscillations in the pumping regime is analyzed numerically, and the effective temperature of the mechanical subsystem in the cooling regime is obtained.

Nanomechanical cat states generated by a dc voltage-driven Cooper pair box qubit

We study a nanoelectromechanical system consisting of a Cooper pair box qubit performing nanomechanical vibrations between two bulk superconductors. We demonstrate that a bias voltage applied to the superconductors may generate states represented by entanglement between qubit states and quantum ’cat states’, i.e. a superposition of the coherent states of the nanomechanical oscillator. We characterize the formation and development of such states in terms of the corresponding Wigner function and entropy of entanglement. Also, we propose an experimentally feasible detection scheme for the effect, in which the average current that attains the specific features created by the entanglement is measured.

Cooling of nanomechanical vibrations by Andreev injection

A nanoelectromechanical weak link composed of a carbon nanotube suspended between two normal electrodes in a gap between two superconducting leads is considered. The nanotube is treated as a movable single level quantum dot in which the position-dependent superconducting order parameter is induced due to the Cooper pair tunneling. We show that electron tunneling processes significantly affect the state of the mechanical subsystem. We found that at a given direction of the applied voltage between the electrodes, the stationary state of the mechanical subsystem has a Boltzmann form with an effective temperature dependent on the parameters of the device. As this takes place, the effective temperature can reach significantly small values (cooling effect). We also demonstrate that nanotube fluctuations strongly affect the dc current through the system. The latter can be used to probe the predicted effects in an experiment.

Nanomechanical vibration profiling of oocytes

Nanomechanical vibration profiling of oocytes

Simple Design on Nanoscale Receivers Using CNT Cantilevers

To develop nanoscale sensors with future potential, a nanoscale receiver utilizing the nanomechanical vibration of a cantilever composed of a carbon nanotube, had been proposed for detecting the digital information carried by wireless signals. The introduced receiver includes two essential parts: a phase detector and demodulator, which employ a reference signal and carrier signal, respectively. Additional components such as electrical circuits and oscillators are required to excite these signals, increasing the sensor size. This study presents a design method for simplifying the receiver structure to contribute to sensor miniaturization. This study theoretically derives a tractable form that can describe the performance of the introduced receiver. This form enables the determination of a simple receiver structure with performance enhancement from a mathematical perspective. Using the proposed method, either the reference wave or carrier signal can be excluded from the receiver, simplifying its structure. The results are demonstrated through a numerical simulation.

Synthetic gauge fields for phonon transport in a nano-optomechanical system.

Gauge fields in condensed matter physics give rise to nonreciprocal and topological transport phenomena and exotic electronic states1. Nanomechanical systems are applied as sensors and in signal processing, and feature strong nonlinearities. Gauge potentials acting on such systems could induce quantum Hall physics for phonons at the nanoscale. Here, we demonstrate a magnetic gauge field for nanomechanical vibrations in a scalable, on-chip optomechanical system. We induce the gauge field through multi-mode optomechanical interactions, which have been proposed as a resource for the necessary breaking of time-reversal symmetry2-4. In a dynamically modulated nanophotonic system, we observe how radiation pressure forces mediate phonon transport between resonators of different frequencies. The resulting controllable interaction, which is characterized by a high rate and nonreciprocal phase, mimics the Aharonov-Bohm effect5. We show that the introduced scheme does not require high-quality cavities, such that it allows exploring topological acoustic phases in many-mode systems resilient to realistic disorder.

Spin-mediated Photomechanical Coupling of a Nanoelectromechanical Shuttle.

We show that nanomechanical vibrations in a magnetic shuttle device can be strongly affected by external microwave irradiation through photo-assisted electronic spin-flip transitions. Mechanical consequences of these spin flips are due to a spin-dependent magnetic force, which may lead to a nanomechanical instability in the device. We derive a criterion for the instability to occur and analyze different regimes of nanomechanical oscillations. Possible experimental realizations of the spin-mediated photomechanical instability and detection of the device backaction are discussed.

Near-Field Photothermal Heating with a Plasmonic Nanofocusing Probe

Noble metal nanostructures support plasmon resonances—collective oscillation of charge carriers at optical frequencies—and serve as effective tools to create bright light sources at the nanoscale. These sources are useful in broad application areas including, super-resolution imaging and spectroscopy, nanolithography, and near-field optomechanical transducers. The feasibility of these applications relies on efficient conversion of free-space propagating light to plasmons. Recently, we demonstrated a hybrid nanofocusing scheme for efficient coupling of light to plasmons at the apex of a scanning probe. In the approach, free-space light is coupled to propagating surface plasmon polaritons (SPPs) on the tapered shaft of the scanning probe. The SPPs propagate adiabatically towards the probe tip where they are coupled to localized plasmons (LSPs). The nanofocusing scheme was explored in a near-field scanning optical microscope for super-resolution imaging, near-field transduction of nanomechanical vibrations, and local detection of ultrasound. Owing to the strong concentration of light at the probe, significant heating of the tip and a sample positioned in the optical near-field is expected. This paper investigates the local heating produced by the plasmonic nanofocusing probe under steady-state conditions using the tip-enhanced Raman scattering approach. In addition, a finite element model is explored to study the coupling of free propagating light to LSPs, and to estimate the temperature rise expected in a halfspace heated by absorption of the LSPs. This study has implications for exploring the plasmonic nanofocusing probe in heat-assisted nanofabrication and fundamental studies of nanoscale heat transport in materials.

Real-Time Viscosity and Mass Density Sensors Requiring Microliter Sample Volume Based on Nanomechanical Resonators

A microcantilever based method for fluid viscosity and mass density measurements with high temporal resolution and microliter sample consumption is presented. Nanomechanical cantilever vibration is driven by photothermal excitation and detected by an optical beam deflection system using two laser beams of different wavelengths. The theoretical framework relating cantilever response to the viscosity and mass density of the surrounding fluid was extended to consider higher flexural modes vibrating at high Reynolds numbers. The performance of the developed sensor and extended theory was validated over a viscosity range of 1-20 mPa·s and a corresponding mass density range of 998-1176 kg/m(3) using reference fluids. Separating sample plugs from the carrier fluid by a two-phase configuration in combination with a microfluidic flow cell, allowed samples of 5 μL to be sequentially measured under continuous flow, opening the method to fast and reliable screening applications. To demonstrate the study of dynamic processes, the viscosity and mass density changes occurring during the free radical polymerization of acrylamide were monitored and compared to published data. Shear-thinning was observed in the viscosity data at higher flexural modes, which vibrate at elevated frequencies. Rheokinetic models allowed the monomer-to-polymer conversion to be tracked in spite of the shear-thinning behavior, and could be applied to study the kinetics of unknown processes.

Enhanced optical forces in integrated hybrid plasmonic waveguides

We demonstrate gradient optical forces in metal-dielectric hybrid plasmonic waveguides (HPWG) for the first time. The magnitude of optical force is quantified through excitation of the nanomechanical vibration of the suspended waveguides. Integrated Mach-Zehnder interferometry is utilized to transduce the mechanical motion and characterize the propagation loss of the HPWG. Compared with theory, the experimental results have confirmed the optical force enhancement, but also suggested a significantly higher optical loss in HPWG. The excessive loss is attributed to metal surface roughness and other non-idealities in the device fabrication process.

Fabrication of Flux Qubit with a Mechanical Degree of Freedom

We report on the fabrication and characterization of superconducting flux qubit coupled to nanomechanical resonator vibration modes. Anisotropic and isotropic etching processes parameters of plasma created by a reactive ion etching of a CF4 gas, were optimized to suspend one arm of the qubit. One of the beams was characterized using a magnetomotive detection scheme in the transmission regime. And suspended beams with different length coupled to a superconducting flux qubits were characterized at base temperature by performing spectroscopy measurements.

A photonic transistor device based on photons and phonons in a cavity electromechanical system

We present a scheme for photonic transistors based on photons and phonons in a cavity electromechanical system, which is composed of a superconducting microwave cavity coupled to a nanomechanical resonator. Control of the propagation of photons is achieved through the interaction of microwave field (photons) and nanomechanical vibrations (phonons). By calculating the transmission spectrum of the signal field, we show that the signal field can be efficiently attenuated or amplified, depending on the power of a second ‘gating’ (pump) field. This scheme may be a promising candidate for single-photon transistors and pave the way for numerous applications in telecommunication and quantum information technologies.