Enhance Measurement Precision Research Articles

Harnessing center-of-mass excitations in quantum metrology

In quantum metrology, one typically creates correlations among atoms or photons to enhance measurement precision. Here, we show how one can use other excitations to perform quantum-enhanced measurements on the example of center-of-mass excitations of a spin-orbit coupled Bose-Einstein condensate and a Coulomb crystal. We also present a method to simulate a homodyne detection of cent er-of-mass excitations in these systems, which is required for optimal estimation.

Bend-free multiarm interferometers on optical chips

Multiarm interferometers can enhance measurement precision and provide multiparameter capability to the measurement. Their realisation requires multiport beam splitters, which has been a long-standing challenge in free-space and integrated optics. Here, we propose a new type of multiport interferometers suitable for implementation on optical chips. Their prospective advantages over the standard directional-coupler architectures: an arbitrary number of arms, planar architecture and two orders of magnitude reduction in footprint, are achieved by the layout based exclusively on the finite modulated photonic lattices. The inverse design of photonic lattices is facilitated by restricting the light propagation to periodic patterns. The corresponding interferometer model predicts the maximum \(1/\sqrt{N}\) sensitivity scaling with the number of arms N. While the presented design solutions are ubiquitous to all implementations, the advantages are discussed in both the low and high refractive-index contrast platforms. Finally, we provide an outlook on the possibilities for the interferometer applications in distributed classical and quantum measurements.

Higher‐Order Spatially Squeezed Beam for Enhanced Spatial Measurements

AbstractA scheme is proposed to realize high‐precision spatial measurement of laser beams beyond quantum limit using a novel quantum state called the order spatially squeezed state, which is the combination of a bright mode coherent state and squeezed vacuum mode state. An effective technique for the generation of a rectangular shape higher‐order mode squeezed light with a maximum mode order of 5 is experimentally demonstrated using a doubling resonated optical parametric amplifier. Furthermore, the fourth order tilt‐ and displacement‐squeezed beams are constructed and used to perform spatial tilt and displacement measurements, thereby improving the signal‐to‐noise ratio by 10 and 8.6 dB compared to the mode. The results indicate that high‐order spatially squeezed states enhance measurement precision beyond the shot noise limit and are more prominent in back‐action noise reduction. High‐precision spatial measurement has potential practical applications in high‐sensitivity atomic force microscope and super‐resolution quantum imaging.

The Multidimensional Behavioral Health Screen 1.0: A Translational Tool for Primary Medical Care

The Multidimensional Behavioral Health Screen (MBHS) is a brief, 27-item questionnaire designed for screening every patient in primary medical care settings. It measures nine psychopathology constructs that represent the major distinctive core dimensions of the types of behavioral health symptoms most commonly encountered in primary care (anxiety-related, depressive, and attention/cognitive symptoms). The underlying design of the MBHS is based on the major paradigm shift that has occurred in the field of theoretical psychopathology, replacing categorical syndromes, or “disorders,” with hierarchical-dimensional constructs. Existing screening tests such as the PHQ-9 and GAD-7 are based explicitly on the categorical paradigm and thus suffer from the same (numerous) shortcomings as the categorical model itself. The dimensional paradigm supports enhanced measurement precision with very short scales. The goals of the MBHS are threefold: (1) to provide accurate, treatment-relevant behavioral health information to the medical provider; (2) to provide clear referral cut-points; (3) to contribute nine psychometrically sound behavioral health variables to the “healthcare big data cloud” to support future scholarship of discovery. Presented here are the basic psychometric properties of the MBHS, including reliability, convergent and discriminant validity, and classification accuracy, as well as implementation considerations.

Squeezing-enhanced rotating-angle measurement beyond the quantum limit

Aided by quantum sources, quantum metrology helps to enhance measurement precision. Here, we introduce a method to enhance the measurement of a rotation angle. As a proof of principle, assisted by a quantum state called the squeezed orbital-angular-position (OAP) state and balance homodyne detection, we demonstrate in experiments 3 dB-enhanced measurements of a rotation-angle beyond the shot noise limit. A precision of up to 17.7 nrad/Hz is obtained. Furthermore, we discuss means to further improve the measurement with a high-order precision OAP squeezed state. The method holds promise for future practical applications, such as in high-sensitive Sagnac interferometry.

Spatial entanglement patterns and Einstein-Podolsky-Rosen steering in Bose-Einstein condensates.

Many-particle entanglement is a fundamental concept of quantum physics that still presents conceptual challenges. Although nonclassical states of atomic ensembles were used to enhance measurement precision in quantum metrology, the notion of entanglement in these systems was debated because the correlations among the indistinguishable atoms were witnessed by collective measurements only. Here, we use high-resolution imaging to directly measure the spin correlations between spatially separated parts of a spin-squeezed Bose-Einstein condensate. We observe entanglement that is strong enough for Einstein-Podolsky-Rosen steering: We can predict measurement outcomes for noncommuting observables in one spatial region on the basis of corresponding measurements in another region with an inferred uncertainty product below the Heisenberg uncertainty bound. This method could be exploited for entanglement-enhanced imaging of electromagnetic field distributions and quantum information tasks.

Psychometric evaluation of an item bank for computerized adaptive testing of the EORTC QLQ-C30 cognitive functioning dimension in cancer patients

BackgroundThe European Organisation of Research and Treatment of Cancer (EORTC) Quality of Life Group is developing computerized adaptive testing (CAT) versions of all EORTC Quality of Life Questionnaire (QLQ-C30) scales with the aim to enhance measurement precision. Here we present the results on the field-testing and psychometric evaluation of the item bank for cognitive functioning (CF).MethodsIn previous phases (I–III), 44 candidate items were developed measuring CF in cancer patients. In phase IV, these items were psychometrically evaluated in a large sample of international cancer patients. This evaluation included an assessment of dimensionality, fit to the item response theory (IRT) model, differential item functioning (DIF), and measurement properties.ResultsA total of 1030 cancer patients completed the 44 candidate items on CF. Of these, 34 items could be included in a unidimensional IRT model, showing an acceptable fit. Although several items showed DIF, these had a negligible impact on CF estimation. Measurement precision of the item bank was much higher than the two original QLQ-C30 CF items alone, across the whole continuum. Moreover, CAT measurement may on average reduce study sample sizes with about 35–40% compared to the original QLQ-C30 CF scale, without loss of power.ConclusionA CF item bank for CAT measurement consisting of 34 items was established, applicable to various cancer patients across countries. This CAT measurement system will facilitate precise and efficient assessment of HRQOL of cancer patients, without loss of comparability of results.

Research Review: What do we know about psychopathic traits in children?

Research on the topic of child psychopathy has advanced over the past decade increasing what we know. This qualitative review examines the research base for child psychopathy and emphasizes its three dimensions: grandiose-manipulative, callous-unemotional, and daring-impulsive. Literature is reviewed addressing the cognitive, emotional, motivational, personality, parenting, and biological correlates. Support has emerged for the phenotypic construct of child psychopathy, while questions remain regarding definitional issues and key external correlates (e.g., reward and punishment processing, parenting, molecular genetics, brain imaging). While the construct appears to be valid, future work should broaden its focus from callous unemotional traits to all three dimensions of the construct, enhance measurement precision, and examine dimension interactions. Such research could have important implications for CD specification for future versions of the DSM and ICD and speed etiological knowledge and clinical care for youth with conduct problems.

Sensors in the Stream: The High-Frequency Wave of the Present.

New scientific understanding is catalyzed by novel technologies that enhance measurement precision, resolution or type, and that provide new tools to test and develop theory. Over the last 50 years, technology has transformed the hydrologic sciences by enabling direct measurements of watershed fluxes (evapotranspiration, streamflow) at time scales and spatial extents aligned with variation in physical drivers. High frequency water quality measurements, increasingly obtained by in situ water quality sensors, are extending that transformation. Widely available sensors for some physical (temperature) and chemical (conductivity, dissolved oxygen) attributes have become integral to aquatic science, and emerging sensors for nutrients, dissolved CO2, turbidity, algal pigments, and dissolved organic matter are now enabling observations of watersheds and streams at time scales commensurate with their fundamental hydrological, energetic, elemental, and biological drivers. Here we synthesize insights from emerging technologies across a suite of applications, and envision future advances, enabled by sensors, in our ability to understand, predict, and restore watershed and stream systems.

Improved image-based deformation measurement for geotechnical applications

This paper describes and benchmarks a new implementation of image-based deformation measurement for geotechnical applications. The updated approach combines a range of advances in image analysis algorithms and techniques best suited to geotechnical applications. Performance benchmarking of the new approach has used a series of artificial images subjected to prescribed spatially varying displacement fields. An improvement by at least a factor of 10 in measurement precision is achieved relative to the most commonly used particle image velocimetry (PIV) approach for all deformation modes, including rigid-body displacements, rotations, and strains (compressive and shear). Lastly, an example analysis of a centrifuge model test is used to demonstrate the capabilities of the new approach. The strain field generated by penetration of a flat footing and an entrapped sand plug into an underlying clay layer is computed and compared for both the current and updated algorithms. This analysis demonstrates that the enhanced measurement precision improves the clarity of the interpretation.

Quantitative Life Prediction Using High Precision Coulometry with Automotive Current Rates

The experimental verification of a Lithium-ion battery for automotive life requirements utilizes significant laboratory resources and calendar time. If the amount of life testing required to validate a cell design for automotive applications can be reduced, new cell designs could be confidently implemented at lower cost and in shorter time. High precision coulometry (HPC) has recently emerged as a promising candidate for shortening the time required for validating cell life. Literature examples have demonstrated improved identification of the mechanisms causing capacity fade1 and qualitative sorting of higher performing cells2. Academic groups have pioneered this approach but have been primarily limited to testing low currents that are used to probe the rates of side reactions in calendar life scenarios. Our research focus has been the design, development and validation of a 200 A, high precision (<50 ppm current and <25 ppm voltage) battery tester in partnership with Arbin Instruments and Sandia National Laboratory, with the support of the US Department of Energy (DOE) Advanced Research Projects Agency- Energy (ARPA-E)3. The capability to perform high precision measurements at currents up to 200 A means the additional degradation brought about by high-rate cycling can be evaluated in addition to calendar assessments. Additionally, we aim to quantitatively assess performance degradation trends by linking presently measured values to future performance. Validation testing is presented using 5 Ah prismatic cells to quantify the reduction in test time that is practically achievable using high precision measurements. Continuous cycle aging using multiple current profiles and ambient temperatures is conducted with periodic reference performance tests. The mathematical relations between capacity, resistance, coulombic efficiency, and electrode endpoint slippage are leveraged to define various life prediction methods. The reference performance test measurements from both the high precision tester and standard commercial reference tester are entered as inputs into the life prediction models. Improved measurement precision can result in reduced uncertainty bands when extrapolating life metric trends into the latter stages of cell life. Enhanced measurement precision can also enable the quantification of long term trends at earlier stages of testing.

Entanglement and spin squeezing in a network of distant optical lattice clocks

We propose an approach for collective enhancement of precision for remotely located optical lattice clocks and a way of generation of the Einstein-Podolsky-Rosen state of remote clocks. Close to Heisenberg scaling of the clock precision with the number of clocks M can be achieved even for an optical channel connecting clocks with substantial losses. This scenario utilizes a collective quantum nondemolition measurement on clocks with parallel Bloch vectors for enhanced measurement precision. We provide an optimal network solution for distant clocks as well as for clocks positioned in close proximity of each other. In the second scenario, we employ collective dissipation to drive two clocks with oppositely oriented Bloch vectors into a steady state entanglement. The corresponding EPR entanglement provides enhanced time sharing beyond the projection noise limit between the two quantum synchronized clocks protected from eavesdropping, as well as allows better characterization of systematic effects.

Continuous-Wave Frequency-Shifted Interferometry Cavity Ring-Down Gas Sensing With Differential Optical Absorption

This paper proposes a novel frequency-shifted interferometry (FSI) fiber cavity ring-down (CRD) gas sensing with dual-wavelength differential optical absorption that requires no modulation to a continuous-wave source or without fast detection and switching electronics. The fiber cavity is constructed from standard fiber optical components that include a micro-optical gas cell. FSI-CRD experiments are carried out with two wavelengths at 1531.770 and 1532.000 nm. The technique is successfully carried out by measuring acetylene-nitrogen mixtures with acetylene concentrations varying from 0% to 1.0%. A resolution of 7.8125%/dB is obtained. A minimum detectable acetylene concentration of 105.25 ppm was achieved with a 48-mm gas cell. The results show a good linear relationship between acetylene concentration and absorption loss and are in good agreement with existing theories. Dual-wavelength differential optical absorption can enhance measurement precision efficiently and eliminate the influence of various external factors. The relative deviation of measured concentration is less than ±0.29%, measured at 1.0% acetylene concentration over 70 min.

Quantum precision measurement based on squeezed light

According to the Heisenberg uncertainty principle, the precision of any physical quantity measurement is limited by quantum fluctuation in general, which leads to the so-called standard quantum limit (SQL). The SQL can be beaten by using squeezed light, hence enhancing the measurement accuracy. Squeezed light is a typical nonclassical light, it exhibits reduced noise in one quadrature component. Since Caves proposed the scheme of phase measurement enhancement with squeezing, squeezed light has been used to enhance measurement precision in many areas. This review focuses on the following four kinds of precision measurements based on squeezed light: the measurements of relative phase, small lateral displacement and tilt, magnetic field, and clock synchronization. For all of these measurements, vacuum squeezing has been used to enhance measurement precision, while the types of squeezing (squeezing angle, transverse mode, polarization etc.) are different. For phase measurement, quadrature squeezing is injected into the conventionally unused input port of Mach-Zehnder interferometer (MZI) or Michelson interferometer (MI). For displacement or tilt measurement, a vacuum squeezing beam of a special transverse mode is coupled into an intense coherent beam, yielding a spatial-squeezed light whose transverse position or tilt angle noise is lower than that of a classical light beam. Based on the Faraday effect of polarization rotation, the magnetic field can be detected precisely. The precision can be increased further by using the polarization squeezing. The polarization squeezing can be generated by coupling two orthogonal polarized beams together, a coherent beam and a vacuum squeezed beam. Various polarization squeezing can be illustrated on the Poincaré sphere. Finally, in the clock synchronization based on the optical frequency comb, squeezed light can be used to enhance the time measurement precision. A theoretical scheme with multimode squeezing of supermode (a kind of mode describing the frequency mode of a pulse laser beam) is introduced. The squeezing has extensively been applied into the quantum precision measurements such as gravitational wave detection as well as biological measurement and will play a more important role in the near future.

Automation Highlights from the Literature

Automation Highlights from the Literature

Continuous Measurement-While-Drilling Utilizing Strap-Down Multi-Model Surveying System

In the oil drilling process, measurement-while-drilling system is usually used to provide real-time monitoring of the position and orientation of the bottom hole. Usually the bottom drill string attitude is measured on the condition that the drill string is static. Particularly, in rotary steerable drilling application, it is a challenging problem to accurately measure the spatial attitude (inclination, azimuth, and tool face) of the bottom drilling tool with the drill string rotating. A set of “strap-down” measurement system was developed in this paper, the triaxial accelerometer and triaxial fluxgate were installed near the bit, and real-time well deviation and azimuth can been measured. Laboratory experiments show that the dynamic solver methods will meet the project requirements. However, according to the drilling field tests, playback analysis on storage data of the underground measurement indicates that drill string vibration is the main reason for measurement errors. So, by setting a time window, the real-time measurement of the accelerometer and the flux gate signal are processed and analyzed, the movement patterns of the rotary drilling tool at the bottom were judged within the time window. Stick-slip phenomenon is utilized to improve the measurement accuracy and to reduce the impact of lateral vibration of the drilling string on the measurement system. We could take advantage of stick-slip phenomenon because of it cannot be avoided completely, although it should be avoided in order to improve the drilling string operating life. Simulation results showed that recommended dynamic survey approach could effectively enhance measurement precision, and deduce effect of vibration on resolve results.

Determination of element/Ca ratios in foraminifera and corals using cold- and hot-plasma techniques in inductively coupled plasma sector field mass spectrometry

We have developed a rapid and precise procedure for measuring multiple elements in foraminifera and corals by inductively coupled plasma sector field mass spectrometry (ICP-SF-MS) with both cold- [800W radio frequency (RF) power] and hot- (1200W RF power) plasma techniques. Our quality control program includes careful subsampling protocols, contamination-free workbench spaces, and refined plastic-ware cleaning process. Element/Ca ratios are calculated directly from ion beam intensities of 24Mg, 27Al, 43Ca, 55Mn, 57Fe, 86Sr, and 138Ba, using a standard bracketing method. A routine measurement time is 3–5min per dissolved sample. The matrix effects of nitric acid, and Ca and Sr levels, are carefully quantified and overcome. There is no significant difference between data determined by cold- and hot-plasma methods, but the techniques have different advantages. The cold-plasma technique offers a more stable plasma condition and better reproducibility for ppm-level elements. Long-term 2-sigma relative standard deviations (2-RSD) for repeat measurements of an in-house coral standard are 0.32% for Mg/Ca and 0.43% for Sr/Ca by cold-plasma ICP-SF-MS, and 0.69% for Mg/Ca and 0.51% for Sr/Ca by hot-plasma ICP-SF-MS. The higher sensitivity and enhanced measurement precision of the hot-plasma procedure yields 2-RSD precision for μmol/mol trace elements of 0.60% (Mg/Ca), 9.9% (Al/Ca), 0.68% (Mn/Ca), 2.7% (Fe/Ca), 0.50% (Sr/Ca), and 0.84% (Ba/Ca) for an in-house foraminiferal standard. Our refined ICP-SF-MS technique, which has the advantages of small sample size (2–4μg carbonate consumed) and fast sample throughput (5–8samples/hour), should open the way to the production of high precision and high resolution geochemical records for natural carbonate materials.

Robust Quantum Enhanced Phase Estimation in a Multimode Interferometer

By exploiting the correlation properties of ultracold atoms in a multi-mode interferometer, we show how quantum enhanced measurement precision can be achieved with strong robustness to particle loss. While the potential for enhanced measurement precision is limited for even moderate loss in two-mode schemes, multi-mode schemes can be more robust. A ring interferometer for sensing rotational motion with non-interacting fermionic atoms can realize an uncertainty scaling of $1/(N\sqrt{\eta})$ for $N$ particles with a fraction $\eta$ remaining after loss, which undercuts the shot noise limit of two mode interferometers. A second scheme with strongly-interacting bosons achieves a comparable measurement precision and improved readout.

Research on the Bending Charge Sensitivity Distribution of Piezoelectric Quartz

In order to enhance measurement precision of the piezoelectric micro-actuator, by means of the transformation rule of tensor the research on the Bending Charge Sensitivity Distribution of Piezoelectric Quartz is conducted. First by the theories of elasticity and electromagnetism the torsion stress and bound charge are calculated, and the charge measured by the detection electrodes is obtained, which depend on the piezoelectric coefficient d12. Then using the transformation rule of tensor the piezoelectric coefficient d12 in the new coordinate system is calculated, and according to the unrestrained multipurpose optimization method the optimization Cut is obtained. Finally a special designed experiment is performed, and the experimental results show that the bound charge produced by the optimized Cut is about twice larger than that primitive Cut. This research on the bending charge sensitivity will provide a theoretical foundation for disposing the detection electrodes of a new piezoelectric micro-actuator

Underwater acoustic localization for small submersibles

AbstractThis article discusses the complete processing chain of a high‐precision as well as robust underwater localization method. Range and azimuth as well as relative heading are determined for ranges up to 90 m. For ranges up to 10 m the measured precision is 0.05 m for range, 2 deg for direction, and 5 deg for heading of neighboring vehicles. The system is also designed to be deployable in swarms of vehicles as acoustic localization signals are separated by time slots and maximum length sequence (MLS) signatures. The proposed method is based on the consequent exploitation of MLS broadband signal characteristics and the exploration of several methods for each vehicle to estimate ranges, azimuths, and headings of neighboring vehicles. An existing radio‐based swarm communication system provides additional support and leads to enhanced measurement precision and interference robustness. The capabilities and limitations of the proposed systems are experimentally determined and discussed. © 2010 Wiley Periodicals, Inc.