Nanomechanical Oscillator Research Articles

基于单层二硫化钼纳米机械振子的全光学质量传感

基于单层二硫化钼纳米机械振子的全光学质量传感

Investigation of nanomechanical oscillators based on amorphous carbon whiskers in vacuum and at ambient pressure

Nanomechanical oscillators (NMO) on the base of amorphous C nanowhiskers, localized on the tops of W needles have been created and studied. Trajectories of resonant oscillations were visualized using a scanning electron microscope and a confocal laser scanning microscope. Resonant frequencies and the quality factor of NMO were determined at low pressure and in air. Reduction of the nanomechanical oscillators quality factor after the transition from vacuum condition to ambient pressure was not observed.

A universal and ultrasensitive vectorial nanomechanical sensor for imaging 2D force fields.

The miniaturization of force probes into nanomechanical oscillators enables ultrasensitive investigations of forces on dimensions smaller than their characteristic length scales. It also unravels the vectorial character of the force field and how its topology impacts the measurement. Here we present an ultrasensitive method for imaging two-dimensional vectorial force fields by optomechanically following the bidimensional Brownian motion of a singly clamped nanowire. This approach relies on angular and spectral tomography of its quasi-frequency-degenerated transverse mechanical polarizations: immersing the nanoresonator in a vectorial force field not only shifts its eigenfrequencies but also rotates the orientation of the eigenmodes, as a nanocompass. This universal method is employed to map a tunable electrostatic force field whose spatial gradients can even dominate the intrinsic nanowire properties. Enabling vectorial force field imaging with demonstrated sensitivities of attonewton variations over the nanoprobe Brownian trajectory will have a strong impact on scientific exploration at the nanoscale.

Electromechanical transition in quantum dots

The strong coupling between electronic transport in a single-level quantum dot and a capacitively coupled nano-mechanical oscillator may lead to a transition towards a mechanically-bistable and blocked-current state. Its observation is at reach in carbon-nanotube state-of-art experiments. In a recent publication [Phys. Rev. Lett. 115, 206802 (2015)] we have shown that this transition is characterized by pronounced signatures on the oscillator mechanical properties: the susceptibility, the displacement fluctuation spectrum and the ring-down time. These properties are extracted from transport measurements, however the relation between the mechanical quantities and the electronic signal is not always straightforward. Moreover the dependence of the same quantities on temperature, bias or gate voltage, and external dissipation has not been studied. The purpose of this paper is to fill this gap and provide a detailed description of the transition. Specifically we find: (i) The relation between the current-noise and the displacement spectrum. (ii) The peculiar behavior of the gate-voltage dependence of these spectra at the transition. (iii) The robustness of the transition towards the effect of external fluctuations and dissipation.

Heralded Control of Mechanical Motion by Single Spins.

We propose a method to achieve a high degree of control of nanomechanical oscillators by coupling their mechanical motion to single spins. Manipulating the spin alone and measuring its quantum state heralds the cooling or squeezing of the oscillator even for weak spin-oscillator couplings. We analytically show that the asymptotic behavior of the oscillator is determined by a spin-induced thermal filter function whose overlap with the initial thermal distribution of the oscillator determines its cooling, heating, or squeezing. Counterintuitively, the rate of cooling dependence on the instantaneous thermal occupancy of the oscillator renders robust cooling or squeezing even for high initial temperatures and damping rates. We further estimate how the proposed scheme can be used to control the motion of a thin diamond cantilever by coupling it to its defect centers at low temperature.

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.

Gigahertz nanomechanical oscillators based on ions inside cyclic peptide nanotubes: a continuum study

The present work aims to investigate the mechanical oscillatory behavior of ions, and in particular \({{\rm Li}^{+}, {\rm Na}^{+}, {\rm Rb}^{+}}\) and \({{\rm Cl}^{-}}\) ions, inside a cyclo[(–d-Ala–l-Ala)4–] peptide nanotube using the continuum approximation along with the 6–12 Lennard–Jones (LJ) potential function. Assuming that each peptide unit is comprised of an inner and an outer tube, the van der Waals (vdW) potential energy and interaction force between an ion and a cyclic peptide nanotube (CPN) are determined analytically. With respect to the present formulations, a detailed parametric study is conducted on the vdW potential energy and interaction force distributions by varying the number of peptide units. Employing the conservation of mechanical energy principle, a novel expression for precise evaluation of oscillation frequency is introduced. To verify the accuracy of the proposed frequency expression, the results obtained from energy equation are compared with the ones predicted through solving the equation of motion numerically. The effects of number of peptide units and initial conditions including initial separation distance and velocity on the oscillatory behavior of various ions inside CPNs are explored. Among the considered ions, \({{\rm Cl}^{-}}\) ion is found to generate the highest frequency. According to the potential energy profile, one oscillatory zone for one peptide unit and different oscillatory zones for more than one peptide unit are observed. Numerical results indicate that optimal frequency decreases with increasing the number of peptide units and almost remains unchanged when the number of peptide units exceeds four.

Q‐factor study of nanomechanical system “metal tip – carbon nanowhisker” at low and ambient pressure

Nanomechanical oscillators based on amorphous carbon whiskers, localized on the top of tungsten tip were fabricated and investigated. The whiskers were grown in the scanning electron microscope chamber using focused electron beam technique. Oscillation trajectories and amplitude‐frequency characteristic of the oscillator were visualized at low and ambient pressure using a scanning electron microscope and a confocal laser‐scanning microscope, respectively. We experimentally show that at ambient pressure, the resonant frequency decreases significantly but the Q‐factor of the oscillator unexpectedly increases with respect to experimental data acquired at low pressure. The explanation was provided taking into account the role of thin water layer absorbed on the whisker from atmosphere. The model of the coupled oscillators is considered.

Single-molecule mass spectrometry.

In single-molecule mass spectrometry, the mass of each ion is measured individually; making it suitable for the analysis of very large, heterogeneous objects that cannot be analyzed by conventional means. A range of single-molecule mass spectrometry techniques has been developed, including time-of-flight with cryogenic detectors, a quadrupole ion trap with optical detection, single-molecule Fourier transform ion cyclotron resonance, charge detection mass spectrometry, quadrupole ion traps coupled to charge detector plates, and nanomechanical oscillators. In addition to providing information on mass and heterogeneity, these techniques have been used to study impact craters from cosmic dust, monitor the assembly of viruses, elucidate the fluorescence dynamics of quantum dots, and much more. This review focuses on the merits of each of these technologies, their limitations, and their applications. © 2016 Wiley Periodicals, Inc. Mass Spec Rev 36:715-733, 2017.

Coupling of a nanomechanical oscillator and an atomic three-level medium

We theoretically investigate the coupling of an ultracold three-level atomic gas and a nano-mechanical mirror via classical electromagnetic radiation. The radiation pressure on the mirror is modulated by absorption of a probe light field, caused by the atoms which are electromagnetically rendered nearly transparent, allowing the gas to affect the mirror. In turn, the mirror can affect the gas as its vibrations generate opto-mechanical sidebands in the control field. We show that the sidebands cause modulations of the probe intensity at the mirror frequency, which can be enhanced near atomic resonances. Through the radiation pressure from the probe beam onto the mirror, this results in resonant driving of the mirror. Controllable by the two photon detuning, the phase relation of the driving to the mirror motion decides upon amplification or damping of mirror vibrations. This permits direct phase locking of laser amplitude modulations to the motion of a nano-mechanical element opening a perspective for cavity-free cooling through coupling to an atomic gas.

Tunable ponderomotive squeezing induced by Coulomb interaction in an optomechanical system

We investigate the properties of the ponderomotive squeezing in an optomechanical system coupled to a charged nanomechanical oscillator (NMO) nearby via Coulomb force. We find that the introduction of Coulomb interaction allows the generation of squeezed output light from this system. Our numerical results show that the degree of squeezing can be tuned by the Coulomb coupling strength, the power of laser, and the frequencies of NMOs. Furthermore, the squeezing generated in our approach can be used to measure the Coulomb coupling strength.

Stationary entanglement between two nanomechanical oscillators induced by Coulomb interaction**Project supported by the Major Research Plan of the National Natural Science Foundation of China (Grant No. 91121023), the National Natural Science Foundation of China (Grant Nos. 61378012, 60978009, and 11574092), the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20124407110009), the National Basic Research

We propose a scheme for entangling two nanomechanical oscillators by Coulomb interaction in an optomechanical system. We find that the steady-state entanglement of two charged nanomechanical oscillators can be obtained when the coupling between them is stronger than a critical value which relies on the detuning. Remarkably, the degree of entanglement can be controlled by the Coulomb interaction and the frequencies of the two charged oscillators.

Study of micro- and nanomechanical oscillators based on crystalline W and amorphous C whiskers

Nanomechanical oscillators (NMO) on the basis of crystalline W (tungsten) microwhiskers and amorphous C (carbon) nanowhiskers localized on the top of W tips are created and studied. Trajectories of single and coupled resonant oscillations are visualized, resonant frequencies and quality factor of NMO are determined. Trajectories of coupled resonant oscillations of NMO are simulated. Calculation results are qualitatively in agreement with the experimental data.

Electronically controlled plasmonic switch using a nanomechanical oscillator and metallic nanoparticle hybrid system

Here we investigate the mechanically induced transparency in a hybrid system which consists of a nanomechanical oscillator and metal nanoparticles. In this system, the effective coupling is provided by the Coulomb interaction between the charged oscillator and nanoparticles in the hybrid system under the pumping of input light. By quantizing the plasmonic field, the Hamiltonian of the hybrid system is derived. Moreover, by solving the quantum Langevin equations, we show that the system exhibits mechanically induced transparency properties on the transmission spectrum, and the transparency window could be tuned by changing the coupling strength. We also discuss the applications of the system as a plasmonic switch.

Measurement-based control of a mechanical oscillator at its thermal decoherence rate

In real-time quantum feedback protocols, the record of a continuous measurement is used to stabilize a desired quantum state. Recent years have seen successful applications of these protocols in a variety of well-isolated micro-systems, including microwave photons and superconducting qubits. However, stabilizing the quantum state of a tangibly massive object, such as a mechanical oscillator, remains very challenging: the main obstacle is environmental decoherence, which places stringent requirements on the timescale in which the state must be measured. Here we describe a position sensor that is capable of resolving the zero-point motion of a solid-state, 4.3-megahertz nanomechanical oscillator in the timescale of its thermal decoherence, a basic requirement for real-time (Markovian) quantum feedback control tasks, such as ground-state preparation. The sensor is based on evanescent optomechanical coupling to a high-Q microcavity, and achieves an imprecision four orders of magnitude below that at the standard quantum limit for a weak continuous position measurement--a 100-fold improvement over previous reports--while maintaining an imprecision-back-action product that is within a factor of five of the Heisenberg uncertainty limit. As a demonstration of its utility, we use the measurement as an error signal with which to feedback cool the oscillator. Using radiation pressure as an actuator, the oscillator is cold damped with high efficiency: from a cryogenic-bath temperature of 4.4 kelvin to an effective value of 1.1 ± 0.1 millikelvin, corresponding to a mean phonon number of 5.3 ± 0.6 (that is, a ground-state probability of 16 per cent). Our results set a new benchmark for the performance of a linear position sensor, and signal the emergence of mechanical oscillators as practical subjects for measurement-based quantum control.

Reversible work extraction in a hybrid opto-mechanical system

With the progress of nano-technology, thermodynamics also has to be scaled down, calling for specific protocols to extract and measure work. Usually, such protocols involve the action of an external, classical field (the battery) of infinite energy, that controls the energy levels of a small quantum system (the calorific fluid). Here we suggest a realistic device to reversibly extract work in a battery of finite energy : a hybrid optomechanical system. Such devices consist of an optically active two-level quantum system interacting strongly with a nano-mechanical oscillator that provides and stores mechanical work, playing the role of the battery. We identify protocols where the battery exchanges large, measurable amounts of work with the quantum emitter without getting entangled with it. When the quantum emitter is coupled to a thermal bath, we show that thermodynamic reversibility is attainable with state-of-the-art devices, paving the road towards the realization of a full cycle of information-to-energy conversion at the single bit level.

Giant resonance tuning of micro and nanomechanical oscillators.

We present a method to tune the resonance frequency and the Q-factor of micro and nano-metric mechanical oscillators. A counteracting loop drives a capacitive force applied to the oscillator. The proportional and differential gains are used to shift the resonance frequency up to 75% and to tune the Q-factor of the oscillator, by changing its effective stiffness and damping ratio. The oscillator position is monitored in a large bandwidth with a fiber-optic based interferometer. We applied this simple operational scheme with different oscillators for modifying easily their dynamical properties. Compared to alternative methods requiring external fields, our method can either increase or decrease the resonance frequency in a frequency range much more extended. This opens up a wide range of applications, from force sensors with extremely low elastic constants but high quality factor to tunable energy harvesters or to high-frequency tuning of radio frequency filters. The control scheme can work in different media, and is then suitable to be applied to biological sensors and actuators.

Playing the notes of DNA with light: extremely high frequency nanomechanical oscillations

We use a double nanohole (DNH) optical tweezer with two trapping lasers beating to excite the vibrational modes of single-stranded DNA (ssDNA) fragments in the extremely high frequency range. We find the resonant vibration frequency of a 20 base ssDNA to be 40 GHz. We show that the change in the resonant frequency for different lengths of the DNA strand is in good agreement with one dimensional lattice vibration theory. Thus the DNH tweezer system could distinguish between different lengths of DNA strands with resolution down to a few bases. By varying the base sequence and length, it is possible to adjust the resonance frequency vibration spectrum. The technique shows the potential for use in sequencing applications if we can improve the resolution of the present system to detect changes in resonant frequency for a single base change in a given sequence. The technique is single-molecule and label-free as compared to the existing methods used for DNA characterization like gel electrophoresis.

Detecting nanoscale vibrations as signature of life

The existence of life in extreme conditions, in particular in extraterrestrial environments, is certainly one of the most intriguing scientific questions of our time. In this report, we demonstrate the use of an innovative nanoscale motion sensor in life-searching experiments in Earth-bound and interplanetary missions. This technique exploits the sensitivity of nanomechanical oscillators to transduce the small fluctuations that characterize living systems. The intensity of such movements is an indication of the viability of living specimens and conveys information related to their metabolic activity. Here, we show that the nanomotion detector can assess the viability of a vast range of biological specimens and that it could be the perfect complement to conventional chemical life-detection assays. Indeed, by combining chemical and dynamical measurements, we could achieve an unprecedented depth in the characterization of life in extreme and extraterrestrial environments.

Single molecule as a local acoustic detector for mechanical oscillators.

A single molecule can serve as a nanometer-sized detector of acoustic strain. Such a nanomicrophone has the great advantage that it can be placed very close to acoustic signal sources and high sensitivities can be achieved. We demonstrate this scheme by monitoring the fluorescence intensity of a single dibenzoterrylene molecule in an anthracene crystal attached to an oscillating tuning fork. The characterization of the vibration amplitude and of the detection sensitivity is a first step towards detection and control of nanomechanical oscillators through optical detection and feedback.