Interferometric Experiments Research Articles

Reviewing Michelson Interferometer Experiment and Measuring the Speed of Starlight

The wave-aether model was proposed long time ago. We study Michelson interferometer experiment and find that its theoretical calculation erroneously neglected the aether drag effect. We take the drag effect into account and reanalyze the theoretical interference pattern shift. The result is null because the drag coefficient of aether is zero. Such that the wave-aether model fulfills all light propagation characteristics. We design and implement a system to measure the starlight speed by comparing to that from a local source. We observe that the arrival times are different. It implies the apparent speeds of starlights are not equal to c.

Application of laser light scattering to the determination of molecular weight, second virial coefficient, and radius of gyration of chitosan

The static laser light scattering technique was applied to determine the molecular weight, second virial coefficient, and radius of gyration of chitosan in aqueous solutions at room temperature. The angular distribution of the intensity of light scattered from chitosan solutions at different concentrations was exploited to calculate the weight-average molecular weight, second virial coefficient, and the radius of gyration by applying the Zimm plot method. The refractive index of the solvent and refractive index increment required for the determination of these parameters were determined experimentally using a home-built Mach-Zehnder interferometer. A continuous wave He-Ne laser operating at a wavelength of 543 nm and at a power of 2 mW was used as a light source for both light scattering and Mach-Zehnder interferometer experiments. The calculated values of the refractive index increment, the weight-average molecular weight, the second virial coefficient and the radius of gyration were found to be 0.2378 mL/g, 7.96 × 105 g/mol, 3.1 × 10−5 mol mL/g2, and 207 nm, respectively.

Statistics of orthogonality catastrophe events in localised disordered lattices

We address the phenomenon of statistical orthogonality catastrophe in insulating disordered systems. In more detail, we analyse the response of a system of non-interacting fermions to a local perturbation induced by an impurity. By inspecting the overlap between the pre- and post-quench many-body ground states we fully characterise the emergent statistics of orthogonality events as a function of both the impurity position and the coupling strength. We consider two well-known one-dimensional models, namely the Anderson and Aubry–André insulators, highlighting the arising differences. Particularly, in the Aubry–André model the highly correlated nature of the quasi-periodic potential produces unexpected features in how the orthogonality catastrophe occurs. We provide a quantitative explanation of such features via a simple, effective model. We further discuss the incommensurate ratio approximation and suggest a viable experimental verification in terms of charge transfer statistics and interferometric experiments using quantum probes.

Spectra in nested Mach–Zehnder interferometer experiments

By the means of the standard quantum mechanics formalism I present an explicit derivation of the structure of power spectra in Danan et al. and Zhou et al. experiments with nested dynamically changing Mach–Zehnder interferometers. The analysis confirms that we observe prominent, first-order peaks on frequencies related to some of the elements of the interferometer, but not on others. However, as I shall demonstrate, there are also other, weaker effects related to all relevant elements of the setup. In case of the Danan et al. setup, there are even peaks at all frequencies of element oscillations. When confronted in an experiment, these observations shall challenge the interpretation of the experiments based on anomalous trajectories of light.

Capacity and Entropy of a Retro-Causal Channel Observed in a Twin Mach-Zehnder Interferometer During Measurements of Pre- and Post-Selected Quantum Systems.

Simple intuitive models are presented for the capacity and entropy of retro-causal channels in measured ensembles of quantum systems which can be represented as statistical mixtures of pre-selected only and pre- and post-selected systems. Measurement data from a twin Mach-Zehnder interferometer experiment are used in these models to discuss the capacity and entropy of an apparent retro-causal channel observed in the experimental data. It is noted that low capacity/low entropy retro-causal channels can exist in strong measurement systems.

AN IMPROVED INTERFEROMETRIC CALIBRATION METHOD BASED ON INDEPENDENT PARAMETER DECOMPOSITION

Abstract. Interferometric SAR is sensitive to earth surface undulation. The accuracy of interferometric parameters plays a significant role in precise digital elevation model (DEM). The interferometric calibration is to obtain high-precision global DEM by calculating the interferometric parameters using ground control points (GCPs). However, interferometric parameters are always calculated jointly, making them difficult to decompose precisely. In this paper, we propose an interferometric calibration method based on independent parameter decomposition (IPD). Firstly, the parameters related to the interferometric SAR measurement are determined based on the three-dimensional reconstruction model. Secondly, the sensitivity of interferometric parameters is quantitatively analyzed after the geometric parameters are completely decomposed. Finally, each interferometric parameter is calculated based on IPD and interferometric calibration model is established. We take Weinan of Shanxi province as an example and choose 4 TerraDEM-X image pairs to carry out interferometric calibration experiment. The results show that the elevation accuracy of all SAR images is better than 2.54 m after interferometric calibration. Furthermore, the proposed method can obtain the accuracy of DEM products better than 2.43 m in the flat area and 6.97 m in the mountainous area, which can prove the correctness and effectiveness of the proposed IPD based interferometric calibration method. The results provide a technical basis for topographic mapping of 1 : 50000 and even larger scale in the flat area and mountainous area.

Development of an Interactive Multimedia Michelson Interferometer Experiment

We developed the interactive multimedia lesson for Michelson Interferometer experiment to compare learning achievement between students who learn with and without the interactive multimedia and to study student’s satisfaction of the interactive multimedia lesson. Michelson Interferometer experiment is the lesson in the Intermediate Physics Laboratory for the second year of Applied Physics students of the Rajamangala University of Technology Thanyaburi. In this experiment, students have to count numbers of light fringes to determine the wavelength of He-Ne laser. We also developed a light counting device providing better experiment results with only 0.032% error compared to counting only by eyes. The efficiency of the interactive multimedia lesson evaluated by 3 experts both in content and production technique of the courseware was 4.45 meaning that the developed the Interactive Multimedia lesson was qualified at a good level. The Interactive Multimedia had the effectiveness at 92.12:80.38 which was higher than standard criteria set (80:80). The post-test scores of students who studied with interactive multimedia were significantly higher than the pre-test score at .05 level, and the student’s satisfaction of the interactive multimedia lesson was 4.25 which students most preferred the Interactive Multimedia Michelson interferometer experiment at a good level.

A Reanalysis of the Two Swimmers Problem, as Frequent Model of Michelson’s Interferometric Experiment Demonstrating that Transversal Path Is Not an Isosceles but a Right Triangle and the Race Will End in a Tie

The article initially reviews various works describing the physical model (PM) of Michelson’s interferometric experiment (ME), represented by the race between two swimmers Sw1, Sw2 (or boats, or planes, or sound signals, etc.). The two swimmers must each swim the same distance, but Sw1 will swim along the river flow, and Sw2 will swim perpendicularly to this direction. In all such works, it is considered that Sw2’s path will require less time and that it will reach the start point first. However, in this work, it has been determined that in order to make this possible, Sw2 must not observe the orthogonality rule of his start direction. This action would be deceitful to the arbiters and thus considered as non-fair-play towards Sw1. The article proves by swimming times calculus, that if the fair-play rules are observed, then the correct crosswise path (in water reference frame) is a right triangle instead of the isosceles triangle considered by Michelson. Consequently, the two times shall be perfectly equal and the race ends in a tie, and the myth of Sw2 as the race winner shall be debunked. Note that the same result shall also be applicable to Michelson’s interferometric experiment (ME) as well as to any similar experiment. Therefore, utilising the isosceles triangle as the transversal path in PM and also in ME is an erroneous act.

Longitudinal and seasonal variations of O(1D) nightglow emission maxima at southern midlatitudes

The Wind Imaging Interferometer (WINDII) experiment on the Upper Atmosphere Research Satellite (UARS) offers a global view of the O(1D) airglow emission rates and neutral winds over the entire altitude range from 190 to 300 km, and provides a unique means for drawing a self-consistent picture of the state of the nighttime upper thermosphere at southern mid-latitudes and by proxy–the ionosphere. The focus of the current study is an investigation of the global seasonal, local time, altitude and longitudinal variability of O(1D) nightglow at southern mid-latitudes (20°S–40°S) employing multi-year observations of O(1D) airglow VERs and neutral winds over the same altitude range and by the same instrument. The results reported here are from four austral seasons, two summers (December solstice, 1992–1993 and 1994–1995), and two equinoxes (March and September 1992). A clear midnight O(1D) VER enhancement is observed at high solar activity during austral summer solstice and equinox (DJF, 1992–1993, and SON, 1992) and at low solar activity during summer (DJF, 1994–1995). The midnight VER enhancement was followed by a wave 4 signature developing after local midnight during all seasons considered particularly during high solar activity summer solstice and spring equinox. The analysis also revealed a complex global O(1D) nightglow VER field, which independently of season exhibited vast regions of very low O(1D) VER (1–4 photons cm−3s−1) in the pre-midnight period at 200°E–300°E longitude throughout the entire latitude range of 5°S–40°S. Particularly noticeable was a region of very low VERs observed poleward of 25°S throughout the local night independent of local time and seasons, over the longitude range from 340°E to 100°E–120°E, which was co-located with the midlatitude ionospheric trough. Another persistent signature observed was an enhancement at 100°E–200°E, at latitudes south of 25°S–30°S, which corresponds to a wave 1 or is a part of a wave 2 signature, likely the result of transport of plasma associated with the Weddell Sea Anomaly. The most prominent result revealed by the study is the role of the wave 4 and wave 1 in the coupling of the lower atmosphere and the thermosphere/ionosphere.

Emulating Simulations of Cosmic Dawn for 21 cm Power Spectrum Constraints on Cosmology, Reionization, and X-Ray Heating

Abstract Current and upcoming radio interferometric experiments are aiming to make a statistical characterization of the high-redshift 21 cm fluctuation signal spanning the hydrogen reionization and X-ray heating epochs of the universe. However, connecting 21 cm statistics to the underlying physical parameters is complicated by the theoretical challenge of modeling the relevant physics at computational speeds quick enough to enable exploration of the high-dimensional and weakly constrained parameter space. In this work, we use machine learning algorithms to build a fast emulator that can accurately mimic an expensive simulation of the 21 cm signal across a wide parameter space. We embed our emulator within a Markov Chain Monte Carlo framework in order to perform Bayesian parameter constraints over a large number of model parameters, including those that govern the Epoch of Reionization, the Epoch of X-ray Heating, and cosmology. As a worked example, we use our emulator to present an updated parameter constraint forecast for the Hydrogen Epoch of Reionization Array experiment, showing that its characterization of a fiducial 21 cm power spectrum will considerably narrow the allowed parameter space of reionization and heating parameters, and could help strengthen Planck's constraints on . We provide both our generalized emulator code and its implementation specifically for 21 cm parameter constraints as publicly available software.

Statistical uncertainty in the dark-field and transmission signal of grating interferometry.

We present a framework to estimate the fundamental statistical uncertainty of grating interferometer experiments based on a Monte-Carlo method. Using the framework, we are able to determine the uncertainty of individual measurements as well as suggesting experimental protocols that minimise the statistical uncertainty for given overall exposure times. The method presented here is valid for both X-rays and neutrons and can be generalised for any modulation measurement.

Gravitational waves in doubly coupled bigravity

We consider gravitational waves from the point of view of both their production and their propagation in doubly coupled bigravity in the metric formalism. In bigravity, the two gravitons are coupled by a non-diagonal mass matrix and show birefrigence. In particular, we find that one of the two gravitons propagates with a speed which differs from one. This deviation is tightly constrained by both the gravitational Cerenkov effect and the energy loss of binary pulsars. When emitted from astrophysical sources, the Jordan frame gravitational wave, which is a linear combination of the two propagating gravitons, has a wave form displaying beats. The best prospect of detecting this phenomenon would come from nano-Hertz interferometric experiments.

Fermionic Lorentz violation and its implications for interferometric gravitational-wave detection

The recent direct detection of gravitational waves reported by Advanced LIGO has inspired the current article. In this context, a particular Lorentz-violating framework for classical, massive particles is the focus. The latter is characterized by a preferred direction in spacetime comprised of CPT-odd components with mass dimension 1. Curvature effects in spacetime, which are caused by a propagating gravitational wave, are assumed to deform the otherwise constant background field. In accordance with spontaneous Lorentz violation, a particular choice for the vector field is taken, which was proposed elsewhere. The geodesic equations for a particle that is subject to this type of Lorentz violation are obtained. Subsequently, their numerical solutions are computed and discussed. The particular model considered leads to changes in the particle trajectory whose impact on interferometric gravitational-wave experiments such as LIGO will be studied.

Split-And-Delay Unit for FEL Interferometry in the XUV Spectral Range

In this work we present a reflective split-and-delay unit (SDU) developed for interferometric time-resolved experiments utilizing an (extreme ultraviolet) XUV pump–XUV probe scheme with focused free-electron laser beams. The developed SDU overcomes limitations for phase-resolved measurements inherent to conventional two-element split mirrors by a special design using two reflective lamellar gratings. The gratings produce a high-contrast interference signal controlled by the grating displacement in every diffraction order. The orders are separated in the focal plane of the focusing optics, which enables one to avoid phase averaging by spatially selective detection of a single interference state of the two light fields. Interferometry requires a precise relative phase control of the light fields, which presents a challenge at short wavelengths. In our setup the phase delay is determined by an in-vacuum white light interferometer (WLI) that monitors the surface profile of the SDU in real time and thus measures the delay for each laser shot. The precision of the WLI is 1 nm as determined by optical laser interferometry. In the presented experimental geometry it corresponds to a time delay accuracy of 3 as, which enables phase-resolved XUV pump–XUV probe experiments at free-electron laser (FEL) repetition rates up to 60 Hz.

Optimal conventional measurements for quantum-enhanced interferometry

A major obstacle to attain the fundamental precision limit of the phase estimation in an interferometry is the identification and implementation of the optimal measurement. Here we demonstrate that this can be accomplished by the use of three conventional measurements among interferometers with Bayesian estimation techniques. Conditions that hold for the precision limit to be attained with these measurements are obtained by explicitly calculating the Fisher information. Remarkably, these conditions are naturally satisfied in most interferometric experiments. We apply our results to an experiment of atomic spectroscopy and examine robustness of phase sensitivity for the two-axis counter-twisted state suffering from detection noise.

Casimir effect in extended theories of gravity

We study the Casimir vacuum energy density and the Casimir pressure for a massless scalar field confined between two nearby parallel plates in a slightly curved, static spacetime background, employing the weak field approximation in the framework of Extended Theories of Gravity (ETG). Following a perturbative approach upto second order, we find the gravity correction in the ETG to Casimir vacuum energy density and pressure. The corrections to the vacuum energy density in presence of curved spacetime in the framework of General Relativity (GR) are small and today they are still undetected with the current technology. However, future sensitivity improvement in gravitational interferometer experiments will give an useful tool to detect such effect induced by gravity. For these reason we retain interesting from a theoretical point of view generalize the outcomes of GR in the context of ETG. Finally, we find the general relation to constraining the free parameters of the ETG.

The Milky Way’s Supermassive Black Hole: How Good a Case Is It?

The compact and, with 4.3+-0.3 million solar masses, very massive object located at the center of the Milky Way is currently the very best candidate for a supermassive black hole (SMBH) in our immediate vicinity. The strongest evidence for this is provided by measurements of stellar orbits, variable X-ray emission, and strongly variable polarized near-infrared emission from the location of the radio source Sagittarius~A* (SgrA*) in the middle of the central stellar cluster. If SgrA* is indeed a SMBH it will, in projection onto the sky, have the largest event horizon and will certainly be the first and most important target of the Event Horizon Telescope (EHT) Very Long Baseline Interferometry (VLBI) observations currently being prepared. These observations in combination with the infrared interferometry experiment GRAVITY at the Very Large Telescope Interferometer (VLTI) and other experiments across the electromagnetic spectrum might yield proof for the presence of a black hole at the center of the Milky Way. It is, however, unclear when the ever mounting evidence for SgrA* being associated with a SMBH will suffice as a convincing proof. Additional compelling evidence may come from future gravitational wave observatories. This manuscript reviews the observational facts, theoretical grounds and conceptual aspects for the case of SgrA* being a black hole. We treat theory and observations in the framework of the philosophical discussions about "(Anti)Realism and Underdetermination", as this line of arguments allows us to describe the situation in observational astrophysics with respect to supermassive black holes. Questions concerning the existence of supermassive black holes and in particular SgrA* are discussed using causation as an indispensable element. We show that the results of our investigation are convincingly mapped out by this combination of concepts.

Refractive index and phase transformation of sapphire under shock pressures up to 210 GPa

Under shock pressures up to 210 GPa, we measured the refractive index of sapphire at a wavelength of 1550 nm by performing plate impact experiments in order to investigate its refractive-index change behaviors and phase transitions along the Hugoniot state. There were two discontinuities in the refractive index at ∼65 to 92 GPa and ∼144 to 163 GPa, respectively. Moreover, above the Hugoniot elastic limit, the pressure dependence of the refractive index was divided into three segments, and there were large differences in their pressure-change trends: the refractive index decreased evidently with pressure in the first segment (∼20 to 65 GPa), remained nearly constant from ∼92 to ∼144 GPa in the second segment, and obviously increased with pressure in the last segment (∼163 to 210 GPa). Our first-principles calculations suggest that the observed discontinuities were closely related to the corundum-Rh2O3(II) and Rh2O3(II)-CaIrO3 structural transitions, and the shock-induced vacancy point defects could be one factor causing these great discrepancies in pressure-change trends. This work provides sapphire refractive-index information in a megabar-pressure range and clear evidence of its shock structural transitions. This not only has a great significance for the velocity correction of laser interferometer experiments and the analysis of sapphire high-pressure properties but also indicates a possible approach to explore the shock transitions of transparent materials.

Probing a classically conformal B−L model with gravitational waves

We study the cosmological history of the classical conformal $B-L$ gauge extension of the standard model, in which the physical scales are generated via the Coleman-Weinberg-type symmetry breaking. Especially, we consider the thermal phase transition of the U$(1)_{B-L}$ symmetry in the early universe and resulting gravitational-wave production. Due to the classical conformal invariance, the phase transition tends to be a first-order one with ultra-supercooling, which enhances the strength of the produced gravitational waves. We show that, requiring (1) U$(1)_{B-L}$ is broken after the reheating, (2) the $B-L$ gauge coupling does not blow up below the Planck scale, (3) the thermal phase transition completes in almost all the patches in the universe, the gravitational wave spectrum can be as large as $\Omega_{\rm GW} \sim 10^{-8}$ at the frequency $f \sim 0.01$-$1$Hz for some model parameters, and a vast parameter region can be tested by future interferometer experiments such as eLISA, LISA, BBO and DECIGO.

Experimental Demonstration of Direct Path State Characterization by Strongly Measuring Weak Values in a Matter-Wave Interferometer.

A method was recently proposed and experimentally realized for characterizing a quantum state by directly measuring its complex probability amplitudes in a particular basis using so-called weak values. Recently, Vallone and Dequal [Phys. Rev. Lett. 116, 040502 (2016)PRLTAO0031-900710.1103/PhysRevLett.116.040502] showed theoretically that weak measurements are not a necessary condition to determine the weak value. Here, we report a measurement scheme used in a matter-wave interferometric experiment in which the neutron path system's quantum state was characterized via direct measurements, using both strong and weak interactions. Experimental evidence is given that strong interactions outperform weak ones for tomographic accuracy. Our results are not limited to neutron interferometry, but can be used in a wide range of quantum systems.