Microscopic Units Research Articles

Electrospun luminescent aeolotropic conductive film enabled by a photoactive semiconductor as a conductive and luminescent material

It is a crucial task to design and fabricate the microscopic construction unit for researching and developing polyfunctional novel macroscopic aeolotropic conductive films (ACFs). In this work, {High concentration 2,7-dibromo-9-fluorenone (H-DBF)/[polyvinylidene fluoride (PVDF) + polyvinylpyrrolidone (PVP)]}//[low concentration DBF (L-DBF)/(PVDF + PVP)] Janus nanofibers as construction units to directionally arrange to form ACF are devised and facilely constructed by a parallel electrospinning technology. ACF consists of a photoactive semiconductor material concurrently as a luminescent and conductive material. H-DBF displays high conductance and weak luminescence, but L-DBF exhibits low conductance and high luminescence. By taking full advantage of traits of DBF, for the first time, high and low concentrations of DBF are utilized and further integrated into the Janus nanofiber (JN), and thus rational design of construction unit is realized at the microscopic level. Under light illumination, the H-DBF side is conductive and the L-DBF side is insulating, resulting in the fact that the arrayed ACF conducts and insulates along the arranged and perpendicular orientation of JNs respectively. Therefore, the ACF has aeolotropic conductivity by adjusting the DBF content on both sides of Janus nanofiber. When there is no light illumination, the ACF does not have electrically conductive aeolotropy and displays insulativity. The ACF realizes the conversion from non-aeolotropic conductivity to aeolotropic conductivity by converting from no light to light illumination. At the same time, because the luminous intensity of L-DBF is stronger than that of H-DBF, the introduction of L-DBF side can improve the luminous intensity of the ACF and achieve excellent versatility, realizing visualization effect. ACF reveals green luminescence under light illumination. To our knowledge, this is the first time that the sample has tunable aeolotropic conductivity and luminescence by only adjusting the content of a substance. The devising conception and technique play an essential role to develop new-typed ACFs with polyfunction.

Using X‐ray fluorescence to examine ancient Maya granite ground stone in Belize

AbstractWhile ubiquitous among ancient Maya sites in Mesoamerica, archaeological analysts frequently overlook the interpretive potential of ground stone tools. The ancient Maya often made these heavy, bulky tools of coarse‐grained, heterogeneous materials that are difficult to chemically source, unlike obsidian. This paper describes an application of handheld, energy‐dispersive X‐ray fluorescence (XRF) to provenance ground stone artifacts (tools and architectural blocks) composed of granite: a nonhomogenous, phaneritic stone. We present a multicomponent methodology that independently tested whole‐rock, thin‐sectioned, and powdered samples by petrographic microscope, conventional, lab‐based XRF, and portable XRF units, which yielded comparable results. After establishing distinct geochemical signatures for the three geographically restricted granite plutons in Belize, we devised a field‐based XRF application on a whole rock that could replicate the compositional readings of lab‐based XRF on powdered materials with sufficient accuracy and reliability. We applied this multishot XRF technique to granite ground stone items from a range of ancient Maya sites throughout Belize; we discuss two specific case studies herein. Our results underscore the widespread potential of multishot XRF applications for determining the provenance of coarse‐grained, heterogeneous rock materials. These results can help push the boundaries from one‐dimensional, functional explanations of ground stone items to their social and ideological dimensions, alongside deeper understandings of granite resource management.

Mechanism exploration and effective analysis method of shear effect of helically wound structures

Helically wound structures are widely used in practical engineering due to its excellent mechanical property, such as the steel rope, the reinforced armor layer of the marine flexible pipe/cables. The shear stiffness plays an important role in exactly predicting the mechanical response of the helically wound structure, especially for the short structure. There has been no general methodology to directly calculate the shear effect of this type of structure because of the geometrical complexity. This paper introduces and modifies a novel implementation of asymptotic homogenization method so-called NIAH to effectively calculate the shear property of the helically wound structure. This modification of NIAH is derived based on the strain energy equivalence of the macroscopic structure and the microscopic structure so-called the microscopic unit cell, which can be used to quickly calculate the effective stiffness and effective stress. In this paper, the effective stiffness is only discussed. The mechanical mechanism of the shear effect of helically wound structures is firstly explained, and then taking into account the shear effect, a quickly effective analysis method of the mechanical response for the helically wound structure is proposed. The efficient and accurate finite-element model of the unit cell which is used in the numeric implementation of the effective analysis method, is determined through the sensitivity analysis of meshing methods and periodic boundary conditions. Considering the practical application, the implementation of this method is validated for helically wound structures with equal-scale subcomponents and non-equal-scale subcomponents. The influence of the slenderness ratio on the shear effect is also explored in this work. This study provides a meaningful reference for the loading analysis and structural design of helically wound structures. • A method for calculating shear property of helically wound structure is proposed. • Mechanical mechanism of shear effect of helically wound structure is revealed. • The influence of the slenderness ratio of structure on shear effect is studied. • An accurate and efficient model of unit cell is determined by sensitivity analysis. • Shear property of equal-scale and non-equal-scale structures is discussed.

Multiscale Optimization of 3D‐Printed Beam‐Based Lattice Structures through Elastically Tailored Unit Cells

Herein, a numerical multiscale tool is developed to design 3D periodic lattice structures. The work is motivated by the high design freedom of additive manufacturing technologies, which enable complex multiscale lattice structures to be printed. A finite‐element‐based free‐material optimization method is used to determine the ideal orthotropic material properties of a 3D macrostructure space. Subsequently, a population‐based algorithm is established to design optimized microscopic lattice unit cells with the desired structural properties. The design variables are the coordinates of lattice skeleton nodes defined within the 3D lattice unit cell space, and the connectivities between them resulting in a truss skeleton. For the calculation of the mechanical properties of the individual lattice cells, an effective Timoshenko beam‐based finite element calculation method is developed. The macroscale structure can be constructed by periodically filling the domain with the customized unit cell representing a metamaterial. The method is demonstrated by 3D beam problems with compliance constraints. These macroscopic demonstrators of the developed lattice structures were also 3D‐printed. The benefit regarding the weight‐specific structural performance is validated through benchmarking with periodic lattice design solutions using well‐known standard lattice cells.

CaBO2F: A novel deep-UV structural template with high nonlinear optical performance induced by electron delocalization

Nonlinear optical (NLO) materials with deep-ultraviolet (deep-UV) phase-matching capability are of current interest owing to their applications in photoelectric technology. The anionic framework, including the microscopic unit, arrangement, and connection mode, is vital to optimizing the contradictory NLO performances. Herein, the polarizability characteristics of low-dimensional anionic frameworks were investigated. Results revealed that the oriented electron delocalization in a specific direction enhances the polarization and optimizes the NLO performance. A new borate fluoride system, namely CaBO2F, was designed via top-down structural prediction methods. In this system, CaBO2F-I, II, and III with low energy have one-dimensional (BO2)∞ anionic frameworks. The first-principles calculations show that CaBO2F-I, II, and III have wide deep-UV band gaps, suitable birefringence (0.076–0.108@1064 nm), and large second harmonic generation coefficients (2.1–2.7 × KH2PO4 (KDP)). Particularly, CaBO2F-I has a short phase-matching wavelength of 195 nm (Heyd-Scuseria-Ernzerhof (HSE06)), which is the first alkaline earth borate fluoride template with one-dimensional (BO2)∞ that reaches deep-UV phase-matching capability. This result offers a new guideline for exploring novel NLO materials.

Design of mechanical metamaterials with multiple stable stress plateaus

Existing conventional materials are usually difficult to achieve multiple tunable stress plateau characteristics, which hinders their multifunctional applications. This study proposes a multiple stable stress plateau metamaterial. A theoretical model for predicting stress plateaus was established, and its accuracy was verified by experimental and numerical methods. The proposed material exhibits a three-stage deformation mode owing to sequential snap-through and Euler buckling at the microscopic unit cell level under compression. The effect of geometric parameters on the stress plateau was studied. The results indicated that the first plateau stress can be tuned independently by altering the angle between the inclined thin and thick beams, whereas the third plateau stress can be tuned independently by changing the thickness of the vertical thick beams. The first and second plateau stresses can be tuned by varying the thickness ratio of the inclined and vertical thin beams. Moreover, the total number of stress plateaus and the range of each stress plateau could also be tuned by changing the thickness ratio of the inclined and vertical thin beams and the vertical thick beams. Using the energy efficiency method, we obtained the experimental and numerical plateau stresses for each specimen. Notably, the experimental, numerical, and theoretical results were in good agreement. This study is expected to provide guidance for the design of multifunctional metamaterials with multiple tunable stress plateaus.

Micro vision-based measurement of concentricity for both TO base and active area of a APD chip in optical component packaging.

The avalanche photodiode (APD) chip is the core component of the transistor outline (TO). The concentricity between the inner circle (IC) of the APD active area and the outer circle (OC) of the TO base will directly affect a component's key performance indicators, such as external quantum efficiency, receiving sensitivity and responsivity, thereby impacting quality assurance, performance improvement, and stable operation. Nevertheless, as the surge in demand for components increases, the traditional visual inspection relying on manual and microscope has been unable to meet the requirements of mass manufacturing for real-time quality and efficiency. Thus, a Concentricity Microscopic Vision Measurement System (CMVMS) mainly composed of a microscopic vision acquisition unit and an intelligent concentricity measurement unit has been proposed, designed, and implemented. On the basis of analyzing the 3D complex environment of TO components, a coaxial illumination image acquisition scheme that can take into account the characteristics of the OC and IC has been proposed. Additionally, a concentricity image measurement method based on dynamic threshold segmentation has been designed to reduce the interference of complex industrial environment changes on measurement accuracy. The experiment results show that the measurement accuracy of the CMVMS system is over 97%, and with a single measurement time of less than 0.2s, it can better meet the real-time and accuracy requirements. To the best of our knowledge, this is the first report on the realization of real-time concentricity measurement in optical component packaging, and this technology can be extended to other fields of concentricity measurement.

A Novel Efficient Prediction Method for Microscopic Stresses of Periodic Beam-like Structures

This paper presents a novel superposition method for effectively predicting the microscopic stresses of heterogeneous periodic beam-like structures. The efficiency is attributed to using the microscopic stresses of the unit cell problem under six generalized strain states to construct the structural microscopic stresses. The six generalized strain states include one unit tension strain, two unit bending strains, one unit torsion strain, and two linear curvature strains of a Timoshenko beam. The six microscopic stress solutions of the unit cell problem under these six strain states have previously been used for the homogenization of composite beams to equivalent Timoshenko beams (Acta. Mech. Sin. 2022, 38, 421520), and they are employed in this work. In the first step of achieving structural stresses, two stress solutions concerning linear curvatures are transformed into two stress solutions concerning unit shear strains by linearly combining the stresses under two unit bending strains. Then, the six stress solutions corresponding to six generalized unit beam strains are combined together to predict the structural microscopic stresses, in which the six stress solutions serve as basic stresses. The last step is to determine the coefficients of these six basic stress solutions by the principle of the internal work equivalence. It is found that the six coefficients, in terms of the product of the inverse of the effective stiffness matrix and the macroscopic internal force column vector, are the actual generalized strains of the equivalent beam under real loads. The obtained coefficients are physically reasonable because the basic stress solutions are produced by the generalized unit strains. Several numerical examples show that the present method, combining the solutions of the microscopic unit cell problem with the solutions of the macroscopic equivalent beam problem, can accurately and effectively predict the microscopic stresses of whole composite beams. The present method is applicable to composite beams with arbitrary periodic microstructures and load conditions.

2D size of trabecular bone structure units (BSU) correlate more strongly with 3D architectural parameters than age in human vertebrae

Bone tissue is continuously remodeled. In trabecular bone, each remodeling transaction forms a microscopic bone structural unit (BSU), also known as a hemiosteon or a trabecular packet, which is bonded to existing tissue by osteopontin-rich cement lines. The size and shape of the BSUs are determined by the size and shape of the resorption cavity, and whether the cavity is potentially over- or under-filled by the subsequent bone formation. The present study focuses on the recently formed trabecular BSUs, and how their 2D size and shape changes with age and trabecular microstructure. The study was performed using osteopontin-immunostained frontal sections of L2 vertebrae from 8 young (aged 18.5-37.6years) and 8 old (aged 69.1-96.4years) control females, which underwent microcomputed tomography (μCT) imaging prior to sectioning. The contour of 4230 BSU profiles (181-385 per vertebra) within 1024 trabecular profiles were outlined, and their 2D width, length, area, and shape were assessed. Of these BSUs, 22 (0.5%) were generated by modeling-based bone formation (i.e. without prior resorption), while 99.5% were generated by remodeling-based bone formation (i.e. with prior resorption). The distributions of BSU profile width, length, and area were significantly smaller in the old versus young females (p<0.005), and the median profile width, length, and area were negative correlated with age (p<0.018). Importantly, these BSU profile size parameters were more strongly correlated with trabecular bone volume (BV/TV, p<0.002) and structure model index (SMI, p<0.008) assessed by μCT, than age. Moreover, the 2D BSU size parameters were positively correlated to the area of the individual trabecular profiles (p<0.0001), which were significantly smaller in the old versus young females (p<0.024). The BSU shape parameters (aspect ratio, circularity, and solidity) were not correlated with age, BV/TV, or SMI. Collectively, the study supports the notion that not only the BSU profile width, but also its length and area, are more influenced by the age-related bone loss and shift from plates to rods (SMI), than age itself. This implies that BSU profile size is mainly driven by changes in the trabecular microstructure, which affect the size of the resorption cavity that the BSU refills.

Experimental study on chemical-assisted methane flooding for foamy oil reservoirs after primary production

As the foamy oil phenomenon disappears gradually, the produced gas-oil ratio of foamy oil reservoirs increases rapidly and the well productivity declines fast. This paper presents a new EOR method for foamy oil reservoirs after cold production, called chemical-assisted methane flooding (CAMF), which works with the viscosity reducer slug (naphtha) to improve the mobility of heavy oil in the porous media and then the methane gas and foaming liquid slug to form a secondary foamy oil phenomenon under the action of formation shear and foaming liquid. Experimental studies were carried out to understand the mechanisms of CAMF. First, a high temperature and high pressure (HTHP) rheometer was used to evaluate the viscosity reduction performance of naphtha under different temperatures and naphtha contents. Then, a visual HTHP experimental unit was adopted to identify whether secondary foamy oil would be effectively generated. Finally, a specially designed HTHP microscopic flow experimental unit was adopted to reveal the microscopic flow behaviors and EOR mechanisms of CAMF. The study results show that the CAMF process can form an obvious secondary foamy oil phenomenon, proving CAMF as an effective method to enhance the oil recovery for foamy oil reservoirs after primary production. In the process of CAMF, naphtha can improve the mobility of heavy oil, reduce the resistance to the subsequently injected foaming liquid and methane gas when entering deep reservoir, and create conditions for the subsequent formation of secondary foamy oil. The formation of the secondary foamy oil can reduce the injected gas channeling velocity, improve the elastic energy, reduce the viscosity and interfacial tension of heavy oil, and have certain emulsification effects. For this method, the optimal injection timing occurs when the reservoir pressure drops between the bubble point pressure and the pseudo-bubble point pressure. Simultaneous injection of methane gas and foaming liquid is obviously better than alternating injection. if economic conditions permit, a higher surfactant concentration should be used for CAMF, and the optimum gas-liquid ratio for CAMF is 1:1 under the experimental conditions.

Exploring the Polarization Photocatalysis of ZnIn2S4 Material toward Hydrogen Evolution by Integrating Cascade Electric Fields with Hole Transfer Vehicle

AbstractSluggish charge kinetics in photocatalysts and slow hole transfer in oxidation half‐reaction severely limit the photocatalytic activity of hydrogen evolution. ZnIn2S4 with an asymmetrical layered structure of [S–In]–[S–In–S]–[Zn–S] unit cell is a promising material offering asymmetrical crystal polarization to overcome the limitation; however, the polarization‐induced internal electric field by this material remains largely unexplored. Herein, the polarization‐induced internal electric field of ZnIn2S4 by engineering the polarity intensity in microscopic units is demonstrated for the first time. Specifically, ultrathin ZnIn2S4 nanosheets are employed to establish a Ni12P5/ZnIn2S4‐O (NP/ZIS‐O) system with powerful bulk and interface cascade electric field by the oxygen doping and ohmic junction. Enabled by such a design, the photogenerated electrons can rapidly migrate to NP active sites, suppressing the photogenerated electron‐hole pair recombination on ZIS‐O. To further overcome the inefficient hole transfer in oxidation half‐reaction, the preferential dehydrogenation of the α‐CH bond in benzyl alcohol is utilized as a vehicle to facilitate hole transfer. As a result, a remarkably enhanced H2 generation of 15.79 mmol g–1 h–1 is achieved on NP/ZIS‐O, which is 8.16‐fold higher than that of pristine ZnIn2S4. Meanwhile, as a value‐added oxidation product, benzaldehyde can be produced at the rate of 17.63 mmol g–1 h–1. This work presents a collaborative strategy for engineering charge behavior in photocatalysts with polarization features, and provides insights into materials design toward photocatalytic hydrogen production and organic synthesis from the angle of charge kinetics.

Biodiversity of Freshwater Algae from Temple Tank

The study aims to find the diversity of freshwater algae present in the temple tank of Adikesava Perumal temple, Korattur, Chennai. The samples were collected in plastic bottles from various sites in the temple tank. The samples were checked for their pH and temperature. The samples were brought to the laboratory and maintained in an open tank under direct sunlight for 4 weeks. The observation and documentation of the algae were done using the LABOMED VISION 2000 Binocular microscopic unit. Many different varieties of algal species were found from the samples collected. From this, we can conclude that temple tanks act as the best source of a sustainable environment for the growth of algae with diversity and can also be used to monitor the pollution level.

Design of a diamond-like infrared nonlinear optical material LiBS2 with ultra-wide band gap

The exploration of new infrared (IR) nonlinear optical (NLO) materials with large second-harmonic generation (SHG) responses and wide band gap (Eg) is an urgent need but challenging. Starting from the superior unit combination strategy and considering the advantages of borates, chalcogenides and Li elements, we have focused our attention on the exploration of IR NLO materials in the Li-based thioborates. Four novel non-centrosymmetric LiBS2 structures, were obtained successfully through crystal structure prediction by analogy and structural optimization based on the thermodynamic and dynamic stability analysis. Among them, LiBS2-I exhibits an ultra-wide band gap Eg = 4.4 eV, moderate SHG response 0.6 × AgGaS2, and suitable birefringence Δn = 0.04 at 1064 nm, which satisfies the good balance between Eg ≥ 3.0 eV and dij ≥ 0.5 × AgGaS2. The role of microscopic units [BS4] in NLO effect was investigated. This work enriches the structural diversity of thioborates and provides a new approach to the exploration of excellent IR NLO materials.

Synergistic In Vitro Antimicrobial Activity of Triton X-100 and Metformin against Enterococcus faecalis in Normal and High-Glucose Conditions.

The prevention and treatment of oral diseases is more difficult in diabetic patients with poorly controlled blood glucose levels. This study aims to explore an effective, low-cytotoxicity medication for root canal treatment in diabetic patients. The antibacterial effect of the combination of Triton X-100 (TX-100) and metformin (Met) on Enterococcus faecalis (E. faecalis) was evaluated by determining the minimum inhibitory concentration (MIC), minimum bactericidal concentration required to kill 99% bacteria (MBC99) and by conducting dynamic time-killing assays. While the antibiofilm activity was measured by crystal violet (CV) assay, field emission scanning electron microscope (FE-SEM), confocal laser scanning microscope (CLSM) and colony-forming unit (CFU) counting assays. The expression of relative genes was evaluated by real-time quantitative polymerase chain reaction (RT-qPCR), and the cytotoxicity of the new combination on MC3T3-E1 cell was also tested. Results showed that the antibacterial and antibiofilm activities of Met could be significantly enhanced by very low concentrations of TX-100 in both normal and high-glucose conditions, with a much lower cytotoxicity than 2% chlorhexidine (CHX). Thus, the TX-100 + Met combination may be developed as a promising and effective root canal disinfectant for patients with diabetes.

A study on the creep behavior of alloy 709 using in-situ scanning electron microscopy

In this research, an experimental evaluation of creep properties of Alloy 709 in the temperature range of 750–850 °C was undertaken. Alloy 709 is a novel austenitic stainless steel with 20% Cr and 25% Ni by wt% that was developed for application in structural components of nuclear power plants. Creep rupture tests were conducted in an in-situ heating-loading and Scanning Electron Microscope (SEM) unit equipped with Electron Backscatter Diffraction (EBSD) detector and Energy Dispersive Spectroscopy (EDS). “Real-time” creep damage mechanisms of Alloy 709 at various stresses and temperatures using a flat, un-notched sample with continuously reducing cross-section is studied so that the failure and maximum creep damage occurred at the center of the sample where the in-situ SEM imaging could be focused. Accelerated creep tests at temperatures and stresses above service conditions were performed by employing multiple blocks of constant loads where the loads were increased once the sample attained constant creep rate, indicating a secondary creep regime. This technique ensures multiple data points can be obtained from the same test, saves the time required for an otherwise long-term creep test and usage of SEM. Coincident Site Lattice (CSL) boundary maps were collected as control maps before testing, and the grain boundaries were observed during the creep test to understand the effect of grain boundary character on the creep damage mechanism. Void growth, grain boundary separation, and sliding were found to be the main creep mechanisms whose rate is dependent on stress and temperature. Failure mechanisms studied on the fracture surface using SEM fractography were correlated to the sample surface observations to create complementary information to better understand the underline creep mechanism of Alloy 709.

Macro-microscopic Atlas on Heartwood of Pterocarpus santalinus L.f. (Red sandalwood)

Background: Pterocarpus santalinus L.f. (Fam. Leguminosae) is a medium sized, deciduous tree distributed in South India mainly in Andhra Pradesh, Karnataka and Tamil Nadu. The heartwood is highly prized and medicinally useful. The heartwood is used in Indian system of medicine for leucorrhoea, piles, syphilis, vomiting, fever, thirst, purifying blood and in wound healing. Pterocarpus santalinus is one of the ingredients in many Siddha and Ayurvedic formulations namely Cintil Ney, Senchandana Manapagu, Candana Bala, Laksadi Taila and Candanadi lauha. Objective: The present study brings out macro-microscopic atlas on heartwood of medicinal plant Pterocarpus santalinus L.f. Materials and Methods: Sections and powder were observed and photographed under different magnifications with the help of Olympus BX51 Microscopic unit fitted with Olympus Camera. Results: Macroscopically colour, odour and taste; microscopically tyloses, needle eye end fibres, forked fibres with pegged and sharp end, pitted and border pitted vessels, uni-seriate medullary rays, Reddish brownish content, oil globules, simple starch grains, crystal fibres and prismatic crystals of calcium oxalate are the unique diagnostic characters reported. Conclusion: The finding of the present study is believed to be helpful in identifying the genuineness of the heartwood in crude raw drug and also in standardization of herbal formulation containing red sandalwood as ingredient.

Selective Actuation and Tomographic Imaging of Swarming Magnetite Nanoparticles

Micro- and nanomotors have seen substantial progress in recent years for biomedical applications. However, three grand challenges remain: (i) high velocities to overcome the blood flow, (ii) spatially selective control to enable complex navigation, and (iii) integration of a medical, tomographic real-time imaging method to acquire feedback information. Here, we report the combination of active magnetic matter and a medical imaging technique, namely magnetic particle imaging (MPI), which addresses these needs. We synthesize ∼200 nm magnetic nanoparticles and observe a macroscopic, collective effect in a homogeneous magnetic field with a rotating field vector. The nanoparticles form a millimeter-sized cloud and reach speeds of 8 mm s–1. This cloud is imaged and selectively steered with an MPI scanner. Our experimental results are supported by a model that highlights the role of the Mason number, the particle’s volume fraction, and the height of the cloud. The successful introduction of a fast swarm of microscopic units and the spatial selectivity of the technique suggest an effective approach to translate the use of micro- and nanobots into a clinical application.

Direct observation of deterministic macroscopic entanglement

Quantum entanglement of mechanical systems emerges when distinct objects move with such a high degree of correlation that they can no longer be described separately. Although quantum mechanics presumably applies to objects of all sizes, directly observing entanglement becomes challenging as masses increase, requiring measurement and control with a vanishingly small error. Here, using pulsed electromechanics, we deterministically entangle two mechanical drumheads with masses of 70 picograms. Through nearly quantum-limited measurements of the position and momentum quadratures of both drums, we perform quantum state tomography and thereby directly observe entanglement. Such entangled macroscopic systems are poised to serve in fundamental tests of quantum mechanics, enable sensing beyond the standard quantum limit, and function as long-lived nodes of future quantum networks.

Quantum mechanics-free subsystem with mechanical oscillators.

Quantum mechanics sets a limit for the precision of continuous measurement of the position of an oscillator. We show how it is possible to measure an oscillator without quantum back-action of the measurement by constructing one effective oscillator from two physical oscillators. We realize such a quantum mechanics-free subsystem using two micromechanical oscillators, and show the measurements of two collective quadratures while evading the quantum back-action by 8 decibels on both of them, obtaining a total noise within a factor of 2 of the full quantum limit. This facilitates the detection of weak forces and the generation and measurement of nonclassical motional states of the oscillators. Moreover, we directly verify the quantum entanglement of the two oscillators by measuring the Duan quantity 1.4 decibels below the separability bound.

Quantum entanglement goes large

Quantum Systems Quantum entanglement occurs when two separate entities become strongly linked in a way that cannot be explained by classical physics; it is a powerful resource in quantum communication protocols and advanced technologies that aim to exploit the enhanced capabilities of quantum systems. To date, entanglement has generally been limited to microscopic quantum units such as pairs or multiples of single ions, atoms, photons, and so on. Kotler et al. and Mercier de Lepinay et al. demonstrate the ability to extend quantum entanglement to massive macroscopic systems (see the Perspective by Lau and Clerk). Entanglement of two mechanical oscillators on such a large length and mass scale is expected to find widespread use in both applications and fundamental physics to probe the boundary between the classical and quantum worlds. Science , this issue p. [622][1], p. [625][2]; see also p. [570][3] [1]: /lookup/doi/10.1126/science.abf2998 [2]: /lookup/doi/10.1126/science.abf5389 [3]: /lookup/doi/10.1126/science.abh3419