Interferometric Experiments Research Articles

Gravitational tests of electroweak relaxation

We consider a scenario in which the electroweak scale is stabilized via the relaxion mechanism during inflation, focussing on the case in which the back-reaction potential is generated by the confinement of new strongly interacting vector-like fermions. If the reheating temperature is sufficiently high to cause the deconfinement of the new strong interactions, the back-reaction barrier then disappears and the Universe undergoes a second relaxation phase. This phase stops when the temperature drops sufficiently for the back-reaction to form again. We identify the regions of parameter space in which the second relaxation phase does not spoil the successful stabilization of the electroweak scale. In addition, the generation of the back-reaction potential that ends the second relaxation phase can be associated to a strong first order phase transition. We then study when such transition can generate a gravitational wave signal in the range of detectability of future interferometer experiments.

Direct experimental test of commutation relation via imaginary weak value

The canonical commutation relation is the hallmark of quantum theory and Heisenberg's uncertainty relation is a direct consequence of it. But despite its fundamental role in quantum theory, surprisingly, its genuine direct experimental test has hitherto not been performed. In this article, we present a novel scheme to directly test the canonical commutation relation between two dichotomic observables, by exploiting the notion of weak measurement. The imaginary part of a suitably formulated weak value enables this direct test. The measurement of the weak value of a path-qubit observable in a neutron interferometer experiment is used to verify the approach. The experiment is realized using a newly developed technique in our neutron interferometric setup where the neutron's spin/energy degree of freedom serves as ancilla.

Neutron interferometry and tests of short-range modifications of gravity

We consider tests of short-distance modifications of gravity based on neutron interferometry in the scenario of large extra dimensions. Avoiding the non-computability problem in the calculation of the internal gravitational potential of extended sources, typical of models with zero-width brane, we determine the neutron optical potential associated with the higher-dimension gravitational interaction between the incident neutron and a material medium in the context of thick brane theories. Proceeding this way, we identify the physical quantity of the extra dimension model that the neutron interferometry is capable of constraining. We also consider interferometric experiments in which the phase shifter is an electric field, as in the test of the Aharanov-Casher effect. We argue that this experiment, with this non-baryonic source, can be viewed as a test of the short-range behavior of Post-Newtonian parameters that measure the capacity of the pressure and the internal energy for producing gravity.

Filtered pseudo-scalar dark matter and gravitational waves from first order phase transition

If dark matter (DM) acquires mass during a first order phase transition, there will be a filtering-out effect when DM enters the expanding bubble. In this paper we study the filtering-out effect for a pseudo-scalar DM, whose mass may partially come from a first order phase transition in the hidden sector. We calculate the ratio of DM that may enter the bubble for various bubble wall velocities as well as various status of DM (in the thermal equilibrium, or out of the thermal equilibrium) at the time of phase transition, which results in small penetration rate that may affect the final relic abundance of the DM. We further study the stochastic gravitational wave signals emitted by the hidden sector phase transition at the space-based interferometer experiments as the smoking-gun of this model.

A brief overview of 8 m prototype facility of laser interferometer for Taiji pathfinder mission

The 8 m laser interferometer prototype facility is currently being constructed at the Institute of Mechanics, Chinese Academy of Sciences in Beijing, China. It aims to perform laser interferometer experiments and pico-meter precision detection and calibration for Taiji pathfinder mission. The seismically isolated ground and passive vibration isolation are interconnected and the optical benches are stabilized by them, which can form two low-noise testbeds inside a 40 m3 ultra-high vacuum system. An on-ground laser interferometer demonstration used for satellite–satellite tracking will be constructed. In this article, the experimental facility and the employed methods will be described, and the technical details of subsystems will be covered in future papers.

Measurement unification

In many quantum measurement experiments and thought experiments, unexplained results appear. As example, entangled particles appear to interact instantly across distances. A 2018 Measurement paper (Relative Measurement Theory, K. Krechmer, 2018) proposed that the calibration of a measuring apparatus to a reference is required in both quantum measurement models and empirical measurement results. Current quantum measurement models equalize the units but not to a reference. Current empirical measurement indications are equalized to a reference. These two measurements are different. The lack of calibration to a reference in quantum mechanics creates this difference. Including calibration explains the results of the particle spin experiments, quantum teleportation experiments, and Mach-Zehnder interferometer experiments, as well as Mermin's device, Schrödinger's Cat, and other thought experiments.

Differential wavefront sensing and control using radio-frequency optical demodulation.

Differential wavefront sensing is an essential technique for optimising the performance of many precision interferometric experiments. Perhaps the most extensive application of this is for alignment sensing using radio-frequency beats measured with quadrant photodiodes. Here we present a new technique that uses optical demodulation to measure such optical beats at high resolutions using commercial laboratory equipment. We experimentally demonstrate that the images captured can be digitally processed to generate wavefront error signals and use these in a closed loop control system for correct wavefront errors for alignment and mode-matching a beam into an optical cavity to 99.9%. This experiment paves the way for the correction of even higher order errors when paired with higher order wavefront actuators. Such a sensing scheme could find use in optimizing complex interferometers consisting of coupled cavities, such as those found in gravitational wave detectors, or simply just for sensing higher order wavefront errors in heterodyne interferometric table-top experiments.

Phase transition gravitational waves from pseudo-Nambu-Goldstone dark matter and two Higgs doublets

We investigate the potential stochastic gravitational waves from first-order electroweak phase transitions in a model with pseudo-Nambu-Goldstone dark matter and two Higgs doublets. The dark matter candidate can naturally evade direct detection bounds, and can achieve the observed relic abundance via the thermal mechanism. Three scalar fields in the model obtain vacuum expectation values, related to phase transitions at the early Universe. We search for the parameter points that can cause first-order phase transitions, taking into account the existed experimental constraints. The resulting gravitational wave spectra are further evaluated. Some parameter points are found to induce strong gravitational wave signals, which have the opportunity to be detected in future space-based interferometer experiments LISA, Taiji, and TianQin.

New identification method for computer numerical control geometric errors

To address the problems of the low accuracy of geometric error identification and incomplete identification results of the linear axis detection of computer numerical control (CNC) machine tools, a new 21-item geometric error identification method based on double ball-bar measurement was proposed. The model between the double ball-bar reading and the geometric error term in each plane was obtained according to the three-plane arc trajectory measurement. The mathematical model of geometric error components of CNC machine tools is established, and the error fitting coefficients are solved through the beetle antennae search particle swarm optimization (BAS–PSO) algorithm, in which 21 geometric errors, including roll angle errors, were identified. Experiments were performed to compare the optimization effect of the BAS–PSO and PSO and BAS and genetic particle swarm optimization (GA–PSO) algorithms. Experimental results show that the PSO algorithm is trapped in the local optimum, and the BAS–PSO is superior to the other three algorithms in terms of convergence speed and stability, has higher identification accuracy, has better optimization performance, and is suitable for identifying the geometric error coefficient of CNC machine tools. The accuracy and validity of the identification results are verified by the comparison with the results of the individual geometric errors detected through laser interferometer experiments. The identification accuracy of the double ball-bar is below 2.7 µm. The proposed identification method is inexpensive, has a short processing time, is easy to operate, and possesses a reference value for the identification and compensation of the linear axes of machine tools.

Coherence of operations and interferometry

Quantum coherence is one of the key features that fuels applications for which quantum mechanics exceeds the power of classical physics. This explains the considerable efforts that were undertaken to quantify coherence via quantum resource theories. An application of the resulting framework to concrete technological tasks is however largely missing. Here, we address this problem and connect the ability of an operation to detect or create coherence to the performance of interferometric experiments.

Initial Dynamics of Quantum Impurities in a Bose–Einstein Condensate

An impurity immersed in a medium constitutes a canonical scenario applicable in a wide range of fields in physics. Though our understanding has advanced significantly in the past decades, quantum impurities in a bosonic environment are still of considerable theoretical and experimental interest. Here, we discuss the initial dynamics of such impurities, which was recently observed in interferometric experiments. Experimental observations from weak to unitary interactions are presented and compared to a theoretical description. In particular, the transition between two initial dynamical regimes dominated by two-body interactions is analyzed, yielding transition times in clear agreement with the theoretical prediction. Additionally, the distinct time dependence of the coherence amplitude in these regimes is obtained by extracting its power-law exponents. This benchmarks our understanding and suggests new ways of probing dynamical properties of quantum impurities.

Multiphoton interaction phase shifts in attosecond science

Ab initio simulations of a range of interferometric experiments are used to identify a strong dependence on multiphoton phase shifts in above-threshold ionization. A simple rule of thumb for interaction phase shifts is derived to explain both the conservation of photoelectron yield and its absolute CEP-dependence. For instance, it is found that interferometric above-threshold ionization experiments are shifted by $\pi/4$ relative to RABBIT experiments, and that there is no RABBIT-term in a laser-assisted photoionization experiment with odd and even harmonics. Thus, our work helps to resolve the issues of interpretation of quantum dynamics in attosecond and free-electron laser sciences.

Six Reasons to Discard Wave Particle Duality: Thereby Opening New Territory for Young Scientists to Explore

Wave particle duality is a cornerstone of quantum chemistry and quantum mechanics (QM). But there are experiments it cannot explain, such as a neutron interferometer experiment. If QM uses Ψ as its wavefunction, several experiments suggest that nature uses -Ψ instead. The difference between -Ψ and +Ψ is that they describe entirely different pictures of how nature is organized. For example, with -Ψ quantum particles follow waves backwards, which is incompatible with wave-particle-duality, obviously. We call the -Ψ proposal the Theory of Elementary Waves (TEW). It unlocks opportunities for young scientists with no budget to conduct the basic research for a new, unexplored science. This is a dream come true for young scientists: the discovery of uncharted territory. We show how TEW explains the double slit, Pfleegor Mandel and Davisson Germer experiments, Feynman diagrams and the Bell test experiments. We provide innovative research designs for which -Ψ and +Ψ would predict divergent outcomes. What makes QM so accurate is its probability predictions. But Born’s law would yield the same probabilities if it were changed from P = |+Ψ |2 to P = |-Ψ |2. This article is accompanied by a lively YouTube video, “6 reasons to discard wave particle duality.”

Generalized gravity-gradient mitigation scheme

A major challenge in high-precision light-pulse atom interferometric experiments such as in tests of the weak equivalence principle is the uncontrollable dependency of the phase on initial velocity and position of the atoms in the presence of inhomogeneous gravitational fields. To overcome this limitation, mitigation strategies have been proposed, however, valid only for harmonic potentials or only for small branch separations in more general situations. Here we provide a mitigation formula for anharmonic perturbation potentials including local gravitational effects that vary on length scales much smaller than the spatial extent probed by the atoms and originate, e.g., from buildings that surround the experiment. Furthermore, our results are applicable to general interferometer geometries with arbitrary branch separation and allow for compensation of Coriolis effects in rotating reference frames.

Controlling the wetting and evaporation dynamics of non-ideal volatile binary solutions

HypothesisVolatile binary liquid samples on wetting substrates are known to undergo either spreading or contraction tendencies, as a result of solutal Marangoni stresses due to differential volatility. Enhanced spreading is commonly thought to occur when the lower surface tension component is more ‘volatile’, while contraction is expected otherwise. We seek to test the limits of this scenario for various configurations such as sessile drops with free or pinned contact lines, without or with microparticles, and tears-of-wine menisci. ExperimentsWe consider isopropanol- and ethanol–water mixtures, important in numerous applications. We conduct interferometric experiments with sessile droplets for multiple combinations of the initial concentration and controlled ambient humidity (water vapour only), essentially covering the entire range of these parameters. Experiments are also carried out for other configurations mentioned above. FindingsContraction regimes are found in certain situations where spreading is expected, despite the alcohols being more volatile than water. Furthermore, regime reversals occur between cases with different initial liquid concentrations even at zero humidity, and are not necessarily associated with the existence of an azeotropic composition. Such surprising observations are rationalized by a simple model highlighting the often overlooked role of the diffusion coefficient ratio of the two vapours in conjunction with the non-ideality of the mixture. Our picture of the phenomenon is demonstrated to be universal for all configurations studied.

Joint PAZ & TanDEM-X Mission Interferometric Experiments: Interoperability and Products

This article analyzes the potential synergies between the two German satellites of the TerraSAR-X/TanDEM-X (TSX/TDX) mission and the Spanish PAZ satellite. Since both platforms are almost identical and they were launched in the same orbital plane, comparable images of the same area under the same geometry may be regularly acquired by both systems. This allows the simultaneous exploitation of both missions for building larger time series and improving the revisit time of 11 days for each mission up to 4 or 7 days while combining both. The geometric accuracy and the interferometric performance when combining both sensors are investigated, considering different acquisition parameters and land cover types. For this article several images are acquired over German and Spanish calibration test sites. The results obtained when combining acquisitions from satellites of the TSX/TDX and PAZ missions show no loss of performance with respect to image pairs of the same satellite, indicating that both missions might be exploited synergistically in order to improve current monitoring applications or maybe to allow newer application with tighter requirements in terms of revisit time or temporal coverage. In order to explore all these possibilities, a call for scientific proposals will be jointly opened by the coordinators of the scientific activities of both missions in order to explore the simultaneous exploitation of TSX/TDX and PAZ data.

Observation of Pancharatnam-Berry phase for unpolarized and partially polarized light fields

Geometric phase, owing to its topological nature and properties of fault tolerance, plays an important role in devising real world applications in both classical and quantum domain. For classical systems, geometric phase has been observed and studied so far for fully polarized light only. Using an interferometric experiment we demonstrate, for the first time, the existence of Pancharatnam-Berry phase for states covering all empty space inside the Poincaré sphere namely the unpolarized and partially polarized light fields. The observed geometric phase is found identical to its fully polarized counterpart in excellent agreement with the theoretical predictions.

The effect of surface roughness on laser-induced stress wave propagation.

We investigate laser-induced acoustic wave propagation through smooth and roughened titanium-coated glass substrates. Acoustic waves are generated in a controlled manner via the laser spallation technique. Surface displacements are measured during stress wave loading by the alignment of a Michelson-type interferometer. A reflective coverslip panel facilitates capture of surface displacements during loading of as-received smooth and roughened specimens. Through interferometric experiments, we extract the substrate stress profile at each laser fluence (energy per area). The shape and amplitude of the substrate stress profile are analyzed at each laser fluence. Peak substrate stress is averaged and compared between smooth specimens with the reflective panel and rough specimens with the reflective panel. The reflective panel is necessary because the surface roughness of the rough specimens precludes in situ interferometry. Through these experiments, we determine that the surface roughness employed has no significant effect on substrate stress propagation and smooth substrates are an appropriate surrogate to determine stress wave loading amplitude of roughened surfaces less than 1.2 μm average roughness (Ra). No significant difference was observed when comparing the average peak amplitude and loading slope in the stress wave profile for the smooth and rough configurations at each fluence.

Accurate phase analysis of interferometric fringes by the spatiotemporal phase-shifting method

Phase-shifting interferometry (PSI) has been widely applied in the field of accurate optical methodology. However, the fluctuation of background and amplitude intensities due to the instability of laser source, and phase-shifting error or vibration are significant problems for the PSI. In this study, the spatiotemporal phase-shifting method (ST-PSM) (Ri S et al 2019 J. Opt. 21 095702), which is a highly accurate and robust phase analysis method using spatial and temporal intensities information simultaneously, is first applied to laser interferometry to achieve a stable measurement. Through several simulations, three effects of fluctuations in background and amplitude intensities, phase-shifting error were investigated. As a result, we clarified that the periodic phase error with fundamental or second harmonic frequencies occurs in the conventional PSM method, whereas no periodic error occurs in the ST-PSM. Besides, the ST-PSM is also robust to the noise either for uniform or distorted interference fringe images. In the Michelson laser interferometer experiment, the ST-PSM realizes a much more stable measurement of phase and phase gradient distributions than the PSM. We have revealed the excellent performance and the striking advantage that ST-PSM is entirely free of periodic errors in a similar manner to the simulations. Therefore, laser interferometry using the ST-PSM can be expected to apply to various applications, including the extremely accurate non-contact shape and deformation measurement, as well as thickness measurement of transparent materials in life and material sciences.

Revealing topological phase in Pancharatnam–Berry metasurfaces using mesoscopic electrodynamics

Abstract Relying on the local orientation of nanostructures, Pancharatnam–Berry metasurfaces are currently enabling a new generation of polarization-sensitive optical devices. A systematical mesoscopic description of topological metasurfaces is developed, providing a deeper understanding of the physical mechanisms leading to the polarization-dependent breaking of translational symmetry in contrast with propagation phase effects. These theoretical results, along with interferometric experiments contribute to the development of a solid analytical framework for arbitrary polarization-dependent metasurfaces.