Showing papers by "Ephraim Fischbach published in 2005"

Constraining New Forces in the Casimir Regime Using the Isoelectronic Technique

Abstract: We report the first isoelectronic differential force measurements between an Au-coated probe and two Au-coated films, made out of Au and Ge. These measurements, performed at submicron separations using soft microelectromechanical torsional oscillators, eliminate the need for a detailed understanding of the probe-film Casimir interaction. The observed differential signal is directly converted into limits on the parameters $\ensuremath{\alpha}$ and $\ensuremath{\lambda}$ which characterize Yukawa-like deviations from Newtonian gravity. We find $\ensuremath{\alpha}\ensuremath{\lesssim}{10}^{12}$ for $\ensuremath{\lambda}\ensuremath{\sim}200\text{ }\text{ }\mathrm{nm}$, an improvement of $\ensuremath{\sim}10$ over previous limits.

Experimental realization of a quantum quincunx by use of linear optical elements

Abstract: We report the experimental realization of a quantum analog of the classical Galton quincunx and discuss its possible use as a device for quantum computation. Our quantum quincunx is implemented with linear optical elements that allow an incoming photon to interfere with itself while traversing all possible paths from the source to the detector. We show that the experimentally determined intensity distributions are in excellent agreement with theory.

Casimir effect as a test for thermal corrections and hypothetical long-range interactions

Abstract: We have performed a precise experimental determination of the Casimir pressure between two gold-coated parallel plates by means of a micromachined oscillator. In contrast to all previous experiments on the Casimir effect, where a small relative error (varying from 1% to 15%) was achieved only at the shortest separation, our smallest experimental error (~ 0.5%) is achieved over a wide separation range from 170 nm to 300 nm at 95% confidence. We have formulated a rigorous metrological procedure for the comparison of experiment and theory without resorting to the previously used root-mean-square deviation, which has been criticized in the literature. This enables us to discriminate among different competing theories of the thermal Casimir force, and to resolve a thermodynamic puzzle arising from the application of Lifshitz theory to real metals. Our results lead to a more rigorous approach for obtaining constraints on hypothetical long-range interactions predicted by extra-dimensional physics and other extensions of the Standard Model. In particular, the constraints on non-Newtonian gravity are strengthened by up to a factor of 20 in a wide interaction range at 95% confidence.

MEMS-based force sensor: Design and applications

Abstract: Micromachined force detectors are extremely sensitive instruments capable of measuring forces as small as 10−15 N. We describe one such instrument that combines a novel micromachined torsional oscillator with an interferometric position-sensing mechanism that allows fine control of vertical scans. The design, fabrication, and operation of MEMS-based force sensors are described. The sensitivity and unique features of micromachined torsional oscillators allow us to undertake experiments that set new constraints on corrections to Newtonian gravitational forces at separations below 1 μm. Moreover, the measurements provide the most precise characterization of quantum vacuum fluctuation forces to date.

A STUDY ON THE RANDOMNESS OF THE DIGITS OF π

Abstract: We apply a newly-developed computational method, Geometric Random Inner Products (GRIP), to quantify the randomness of number sequences obtained from the decimal digits of π. Several members from the GRIP family of tests are used, and the results from π are compared to those calculated from other random number generators. These include a recent hardware generator based on an actual physical process, turbulent electroconvection. We find that the decimal digits of π are in fact good candidates for random number generators and can be used for practical scientific and engineering computations.

Estimating Parameterized Post-Newtonian Parameters from Spacecraft Radiometric Tracking Data

Abstract: The theory of general relativity can be tested by precisely measuring small changes in the trajectory of a spacecraft traveling near the sun. An important aspect of such a measurement is the potential of estimating the parameterized post-Newtonian parameters γ and β independently. We present a detailed covariance analysis of such a trajectory, analyzing uncertainties in the spacecraft state and γ and β. The radiometric data types simulated in our analysis are range, very long baseline interferometry, and Doppler measurements. Also included are the effects of Earth and spacecraft relative geometries, station-location errors, stochastic accelerations, and uncertainties in the solar quadrupole moment J2 .F or an X-band tracking system, we show that if the steady-state stochastic accelerations, station-location, and solar quadrupole moment errors are known better than 10 −14 km/s 2 , 0.1 m, and 10 −8 , respectively, the experiment can achieve unbiased estimates σγ =8 .90 × × 10 −5 and σβ =4 .09 × × 10 −4 .T oachieve this level of precision on accelerations requires a drag-free spacecraft or accurate accelerometers.

Present status of controversies regarding the thermal Casimir force

Abstract: It is well known that, beginning in 2000, the behavior of the thermal correction to the Casimir force between real metals has been hotly debated. As was shown by several research groups, the Lifshitz theory, which provides the theoretical foundation for the calculation of both the van der Waals and Casimir forces, leads to different results depending on the model of metal conductivity used. To resolve these controversies, the theoretical considerations based on the principles of thermodynamics and new experimental tests were invoked. We analyze the present status of the problem (in particular, the advantages and disadvantages of the approaches based on the surface impedance and on the Drude model dielectric function) using rigorous analytical calculations of the entropy of a fluctuating field. We also discuss the results of a new precise experiment on the determination of the Casimir pressure between two parallel plates by means of a micromechanical torsional oscillator.

Non-Transitive Quantum Games

Abstract: Non-transitivity can arise in games with three or more strategies A, B, C, when A beats B, B beats C, and C beats A, (A > B > C > A). An example is the children’s game “rock, scissors, paper” (R, S, P) where R > S > P > R. We discuss the conditions under which quantum versions of R, S, P retain the non-transitive characteristics of the corresponding classical game. Some physical implications of non-transitivity in quantum game theory are also considered.

Precise comparison of theory and new experiment for the Casimir force leads to stronger constraints on thermal quantum effects and long-range interactions

Abstract: We report an improved dynamic determination of the Casimir pressure between two plane plates obtained using a micromachined torsional oscillator. The main improvements in the current experiment are a significant suppression of the surface roughness of the Au layers deposited on the interacting surfaces, and a decrease in the experimental error in the measurement of the absolute separation. A metrological analysis of all data permitted us to determine both the random and systematic errors, and to find the total experimental error as a function of separation at the 95% confidence level. In contrast to all previous experiments on the Casimir effect, our smallest experimental error ($\sim 0.5$%) is achieved over a wide separation range. The theoretical Casimir pressures in the experimental configuration were calculated by the use of four theoretical approaches suggested in the literature. All corrections to the Casimir force were calculated or estimated. All theoretical errors were analyzed and combined to obtain the total theoretical error at the 95% confidence level. Finally, the confidence interval for the differences between theoretical and experimental pressures was obtained as a function of separation. Our measurements are found to be consistent with two theoretical approaches utilizing the plasma model and the surface impedance over the entire measurement region. Two other approaches to the thermal Casimir force, utilizing the Drude model or a special prescription for the determination of the zero-frequency contribution to the Lifshitz formula, are excluded on the basis of our measurements at the 99% and 95% confidence levels, respectively. Finally, constraints on Yukawa-type hypothetical interactions are strengthened by up to a factor of 20 in a wide interaction range.

Casimir Effect as a Test for Thermal Corrections and Hypothetical Long-Range Interactions

Abstract: We have performed a precise experimental determination of the Casimir pressure between two gold-coated parallel plates by means of a micromachined oscillator. In contrast to all previous experiments on the Casimir effect, where a small relative error (varying from 1% to 15%) was achieved only at the shortest separation, our smallest experimental error ($\sim 0.5$%) is achieved over a wide separation range from 170 nm to 300 nm at 95% confidence. We have formulated a rigorous metrological procedure for the comparison of experiment and theory without resorting to the previously used root-mean-square deviation, which has been criticized in the literature. This enables us to discriminate among different competing theories of the thermal Casimir force, and to resolve a thermodynamic puzzle arising from the application of Lifshitz theory to real metals. Our results lead to a more rigorous approach for obtaining constraints on hypothetical long-range interactions predicted by extra-dimensional physics and other extensions of the Standard Model. In particular, the constraints on non-Newtonian gravity are strengthened by up to a factor of 20 in a wide interaction range at 95% confidence.