- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Design of a Cell-Based Refractometer with Small End-Effects
摘要： In cell-based laser refractometers, interferometer pathlength uncertainty introduced by deformation and stress in the windows through which the beams pass can be the chief factor limiting measurement accuracy. The fractional contribution of pathlength uncertainty to our recent determination of the Boltzmann constant was 9.8 × 10?6, and more than two times larger than the next largest uncertainty component. We briefly describe the error, and propose a design in which cell window effects contribute less than 3 × 10?6 fractional error to the measurement of helium refractivity; performance that would be competitive with state-of-the-art primary thermometry and barometry.
关键词： Interferometry,length metrology,refractive-index gas thermometry
更新于2025-09-10 09:29:36
-
[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Application of AC Quantum Voltmeter for Impedance Comparison
摘要： This paper describes the experimental application of the AC Quantum Voltmeter, developed at PTB, for impedance ratio measurements at voltages up to 5 V and frequencies up to 1 kHz. A calibrator Fluke 5720A and an Aivon DualDAC2 source is used interchanged as the AC voltage source, and as impedances two self-developed resistors of nominal values of 10 kΩ are used. The impedances are measured in a potentiometric way i.e. the AC Quantum Voltmeter measures the RMS voltages on each resistor in time sequence. Measurement results for different set-ups are given and described.
关键词： programmable Josephson voltage standard,AC Josephson metrology,impedance comparison,AC quantum voltmeter
更新于2025-09-10 09:29:36
-
[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - A Switch-Controller for Improved Measurements in the NIST Magnetic Suspension Mass Comparator
摘要： We describe a switch-based control strategy implemented on a proof-of-concept version of the Magnetic Suspension Mass Comparator (MSMC) at the National Institute of Standards and Technology. The MSMC apparatus is used to compare mass artifacts held in air to mass artifacts held in vacuum, without having to remove either artifact from its respective environment; thus, eliminating the need to use empirical sorption models. This comparison is achieved by magnetically suspending the mass artifact held in air. The switch-controller utilizes a combination of a magnetic field and displacement measurement to achieve the desired robustness and stability.
关键词： state feedback,switch controller,magnetic levitation,laser velocimetry,mass metrology,sorption
更新于2025-09-10 09:29:36
-
13.1: <i>Invited Paper:</i> Single-Photon-Capable Detector Arrays in CMOS-Exploring a New Tool for Display Metrology
摘要： The technology of CMOS-compatible Single Photon Avalanche Diodes is evolving rapidly and has matured to the point at which imaging it can address applications. In this report we consider the current suitability and future potential of CMOS-compatible Single Photon Avalanche Diodes to address the particular application of display metrology.
关键词： Display Metrology,dSiPM,Quanta Image Sensor,CMOS,QIS,Complementary Metal Oxide Semiconductor,Digital Silicon Photo-Multiplier,Single Photon Avalanche Diode,SPAD
更新于2025-09-10 09:29:36
-
Temporal stability and absolute composition issues in molecular beam epitaxy of AlGaAs/GaAs THz QCL
摘要： The operation of the terahertz quantum cascade lasers (THz QCL) is strongly dependent on the repeatable fabrication of the well and barrier layers with the certain thicknesses throughout the whole active region stack epitaxial growth. This emphasizes the importance of the strict control of the growth rates and the stability of Si and group III effusion cell fluxes during growth [1]. It was reported [2] that two THz QCLs based on nominally identical multilayer heterostructures Al0.15Ga0.85As/GaAs emit at the different frequencies of 2.59 and 2.75 THz because of unintentional small deviations in the GaAs and AlAs growth rates (4 and 1.6 % respectively). Authors [3] determined the thickness tolerance for working lasing heterostructures to be minimally above 2% while the structures with thickness deviation 4.3 and 6.5 % are not lasing. In [4] the Ga cell temperature has to be increased to maintain a GaAs constant growth rate while the Al cell temperature remains nearly constant because variation in AlAs growth rate can be neglected. By using such growth rate compensation technique the two nominally identical structures approximately 10 mkm overall thick were found to show thickness difference of ~ 1 %. Thus calibration procedures and accurate analysis techniques become crucial to provide enhanced metrology possibilities.
关键词： molecular beam epitaxy,metrology,AlGaAs/GaAs,terahertz quantum cascade lasers,growth rates
更新于2025-09-10 09:29:36
-
Transverse resonance island buckets for synchrotron-radiation based electron time-of-flight spectroscopy
摘要： At the Metrology Light Source (MLS), the compact electron storage ring of the Physikalisch-Technische Bundesanstalt (PTB) with a circumference of 48 m, a specific operation mode with two stable closed orbits for stored electrons was realized by transverse resonance island buckets. One of these orbits is closing only after three turns. In combination with single-bunch operation, the new mode was applied for electron time-of-flight spectroscopy with an interval of the synchrotron radiation pulses which is three times the revolution period at the MLS of 160 ns. The achievement is of significant importance for PTB’s future programs of angular-resolved electron spectroscopy with synchrotron radiation and similar projects at other compact electron storage rings. The scheme applied here for selecting the photons originating from a particular orbit by optical imaging has been used before in fs slicing applications and may be relevant for the BESSY VSR project of the Helmholtz-Zentrum Berlin.
关键词： BESSY VSR,transverse resonance island buckets,electron time-of-flight spectroscopy,Metrology Light Source,synchrotron radiation
更新于2025-09-10 09:29:36
-
Quantum-Limited Loss Sensing: Multiparameter Estimation and Bures Distance between Loss Channels
摘要： The problem of estimating multiple loss parameters of an optical system using the most general ancilla-assisted parallel strategy is solved under energy constraints. An upper bound on the quantum Fisher information matrix is derived assuming that the environment modes involved in the loss interaction can be accessed. Any pure-state probe that is number diagonal in the modes interacting with the loss elements is shown to exactly achieve this upper bound even if the environment modes are inaccessible, as is usually the case in practice. We explain this surprising phenomenon, and show that measuring the Schmidt bases of the probe is a parameter-independent optimal measurement. Our results imply that multiple copies of two-mode squeezed vacuum probes with an arbitrarily small nonzero degree of squeezing, or probes prepared using single-photon states and linear optics, can achieve quantum-optimal performance in conjunction with on-off detection. We also calculate explicitly the energy-constrained Bures distance between any two product loss channels. Our results are relevant to standoff image sensing, biological imaging, absorption spectroscopy, and photodetector calibration.
关键词： Bures distance,loss sensing,quantum Fisher information,optical systems,Quantum metrology
更新于2025-09-09 09:28:46
-
Towards the realization of an optical pressure standard
摘要： A novel pressure standard based on optical interferometry has been realized. The paper presents a preliminary achievement of the system, in which the standard pressure between 1 kPa and 120 kPa is obtained through the measurement of the refractive index of a gas. The response of the optical system has been initially evaluated measuring its sensitivity for nitrogen and air, in terms of the ratio between a pressure variation and the number of detected interferometric fringes. Afterwards, the interferometer has been geometrical characterized in order to perform an absolute measurement of the refractive index of the gas, allowing an optical measurement of the gas pressure. The following step has been to compare the results of a series of measurements obtained with the optical system with a reference pressure standard at 120 kPa. Finally, the standard has been compared with two capacitance diaphragm gauges in the range between 1 kPa and 120 kPa. The device has a relative standard uncertainty equal to 170 ppm at atmospheric pressure.
关键词： Absolute distance,Vacuum standard,Vacuum gauge,Pressure metrology,Refractometry,Laser interferometry
更新于2025-09-09 09:28:46
-
[IEEE 2018 IEEE Photonics Conference (IPC) - Reston, VA, USA (2018.9.30-2018.10.4)] 2018 IEEE Photonics Conference (IPC) - Measuring Thermal Acoustic Radiation with an Optomechanical Antenna
摘要： We optically probe the SiN membrane nanomechanical resonator modes that are strongly coupled to acoustic radiation into the substrate. We use this optomechanical system for temperature metrology by detecting the ballistic transport of thermal excitations from a remote bath.
关键词： Metrology,Temperature Sensors,Optomechanics,Photonics,Thermal Noise,Nanophotonics
更新于2025-09-09 09:28:46
-
Resolving unattainable Cramer-Rao bounds for quantum sensors
摘要： In quantum metrology, it is widely believed that the quantum Cram′er-Rao bound is an attainable bound. However, this is not always true. In order to clarify this point, we explain why the quantum Cram′er-Rao bound cannot be attained. Here, we investigate noiseless channel estimation under energy constraint for states, using a physically reasonable error function, and present a state achieving the optimal rate as well as the attainable bound. We propose an experimental generation of the optimal states for enhanced metrology using squeezing transformations. This makes phase/unitary estimation physically implementable.
关键词： quantum sensor,quantum metrology,phase estimation
更新于2025-09-09 09:28:46