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Hand-gesture controlled wheelchairs help in providing mobility and safety to individuals with physical disabilities or mobility impairments. In this paper, a wheelchair have been fabricated so that it can be controlled by hand-gestures and move smoothly in all 4 directions. The main focus of our research has been to drive down the cost of such a wheelchair as compared to the ones already available in the market to enable penurious people to afford it. An accelerometer sensor is fitted in the data glove to read the hand movements and the information is conveyed to an Arduino microcontroller using wires. The Arduino board controls the pair of DC wiper motors attached at the rear end on each wheel of the wheelchair. The proposed mechanism has demonstrated precise responsiveness to users' hand gestures during trials.

Prior studies on capital investments, including mergers and acquisitions, point to investment irreversibility as the primary factor behind diminished investments during periods of increased policy uncertainty. We show that increased relational risk, due to the potential for counterparty misbehavior or shirking and higher contracting costs, appears to be the primary driver behind the diminished propensity to undertake strategic alliances during enhanced policy uncertainty regimes. Alliances are even less likely during such times when they (a) involve more than two firms, (b) are in industries with greater counterparty risk, and (c) involve partners that require intense contracts., 1 | INTRODUCTION Strategic alliances (1) have gained increasing prominence in the corporate landscape and now occupy a central place in corporate decision-making. Nevin (2014) notes that 'strategic alliances are [...]

Recently, a basis-invariant measure of coherence known as the intrinsic degree of coherence has been established for classical and single-particle quantum states [J. Opt. Soc. Am. B36, 2765 (2019)JOBPDE0740-322410.1364/JOSAB.36.002765]. In this article, we use the same mathematical construction to define the intrinsic degree of coherence of two-qubit states and demonstrate its usefulness in quantifying two-particle quantum correlations and entanglement. In this context, we first show that the intrinsic degree of coherence of a two-qubit state puts an upper bound on the violations of Bell inequalities that can be achieved with the state and that a two-qubit state with an intrinsic degree of coherence less than $ 1/\sqrt 3 $1/3 cannot violate Bell inequalities. We then show that the quantum discord of a two-qubit state, which quantifies the amount of quantum correlations available in the two-qubit state for certain tasks, is bounded from above by the intrinsic degree of coherence of the state. Next, in the context of two-particle entanglement, we show that the range of values that the concurrence of a two-qubit state can take is decided by the intrinsic degree of coherence of the two-qubit state together with that of the individual qubits. Finally, for the polarization two-qubit states generated by the parametric down-conversion of a pump photon, we propose an experimental scheme to measure the intrinsic degree of coherence of two-qubit states. We also present our theoretical study that shows how the intrinsic degree of coherence of a pump photon dictates the maximum intrinsic degree of coherence of the generated two-qubit state.

In the context of the two-dimensional (2D) polarization states of light, the degree of polarization ${P_2}$ is equal to the maximum value of the degree of coherence over all possible bases. Therefore, ${P_2}$ can be referred to as the intrinsic degree of coherence of a 2D state. In addition to (i) the maximum degree of coherence interpretation, ${P_2}$ also has the following interpretations: (ii) it is the Frobenius distance between the state and the maximally incoherent identity state, (iii) it is the norm of the Bloch vector representing the state, (iv) it is the distance to the center of mass in a configuration of point masses with magnitudes equal to the eigenvalues of the state, (v) it is the visibility in a polarization interference experiment, and (vi) it is the weightage of the pure part of the state. Among these six interpretations of ${P_2}$, the Bloch vector norm, Frobenius distance, and center-of-mass interpretations have previously been generalized to derive an analogous basis-independent measure ${P_N}$ for $N$-dimensional (ND) states. In this paper, by extending the concepts of visibility, degree of coherence, and weightage of the pure part to ND spaces, we show that these three remaining interpretations of ${P_2}$ also generalize to the same quantity ${P_N}$, establishing ${P_N}$ as the intrinsic degree of coherence of ND states. We then extend ${P_N}$ to the $N\to\infty$ limit to quantify the intrinsic degree of coherence ${P_\infty}$ of infinite-dimensional states in the orbital angular momentum, photon number, and position-momentum degrees of freedom.

We investigate the effects of four macro variables (trust and cultural, institutional, and geographical distances) on the propensity to form a strategic alliance. From a set of 26 countries, we construct 315 country pairs over the period from 1996 to 2004. We collect our data from the SDC platinum database that identifies how many cross-border strategic alliances occurred between the firms in the country pairs in each year. For each country pair we construct measurements for the macro variables. Then in a multivariate framework, we examine their effects on the number of cross-border alliances. We find that the cross-border alliances are more likely to occur between firms from countries that have higher trust and shorter cultural and geographical distances—the institutional distance does not have an effect. Additional tests show that greater trust lessens the adverse effect of geographical distance, but a shorter cultural distance does not.

•Counties in United States with more social capital lean toward the Democratic Party.•The positive association between social capital left leaning is stronger in counties that have higher incomes, and less religiosity.

We show that in parametric down-conversion the coherence properties of a temporally partially coherent pump field get entirely transferred to the down-converted entangled two-photon field. Under the assumption that the frequency bandwidth of the down-converted signal-idler photons is much larger than that of the pump, we derive the temporal coherence functions for the down-converted field, for both infinitely fast and time-averaged detection schemes. We show that in each scheme the coherence function factorizes into two separate coherence functions with one of them carrying the entire statistical information of the pump field. In situations in which the pump is a Gaussian Schell-model field, we derive explicit expressions for the coherence functions. Finally, we show that the concurrence of time-energy-entangled two-qubit states is bounded by the degree of temporal coherence of the pump field. This study can have important implications for understanding how correlations of the pump field manifest as two-particle entanglement as well as for harnessing energy-time entanglement for long-distance quantum communication protocols.

We study partially coherent fields that have a coherent-mode representation in the orbital-angular-momentummode basis. For such fields, we introduce the concepts of the angular coherence function and the coherence angle. Such fields are naturally produced by the process of parametric down-conversion--a second-order nonlinear optical process in which a pump photon breaks up into two entangled photons, known as the signal and idler photons. We show that the angular coherence functions of the signal and idler fields are directly related to the angular Schmidt (spiral) spectrum of the down-converted two-photon field and thus that the angular Schmidt spectrum can be measured directly by measuring the angular coherence function of either the signal or the idler field, without requiring coincidence detection. [ABSTRACT FROM AUTHOR]

We show that the use of path-entangled states of photons, having nonzero orbital angular momentum (OAM), increases the resolution and sensitivity of angular-displacement measurements performed using an interferometer. In the ideal case of maximally path-entangled states, the resolution of angular-displacement measurements increases by a factor of Nl, while the uncertainty in the measurement of angular displacements scales as 1/Nl, where N is the number of entangled photons, half of which carry, on average, an OAM of +lħ per photon and the other half carry an OAM of -lħ per photon. We analyze measurement schemes for two- and four-photon entangled states produced by parametric down-conversion and, by employing a 4×4 matrix formalism to study the propagation of entangled OAM modes, obtain explicit expressions for the resolution and sensitivity in these schemes. These results constitute an improvement over what could be obtained with N nonentangled photons carrying an orbital angular momentum of ∣l∣ħ per photon. [ABSTRACT FROM AUTHOR]

We describe a procedure to construct a free-space quantum key distribution system that can carry many bits of information per photon. We also describe the current status of our laboratory implementation of these plans.

We demonstrate accurate phase measurement from experimental low photon level interferograms using a constrained optimization method that takes into account the expected redundancy in the unknown phase function. This approach is shown to have significant noise advantage over traditional methods, such as balanced homody ning or phase shifting, that treat individual pixels in the interference data as independent of each other. Our interference experiments comparing the optimization method with the traditional phase-shifting method show that when the same photon resources are used, the optimization method provides phase recoveries with tighter error bars. In particular, rms phase error performance of the optimization method for low photon number data (10 photons per pixel) shows a >5x noise gain over the phase-shifting method. In our experiments where a laser light source is used for illumination, the results imply phase measurement with an accuracy better than the conventional single-pixel-based shot-noise limit that assumes independent phases at individual pixels. The constrained optimization approach presented here is independent of the nature of the light source and may further enhance the accuracy of phase detection when a nonclassical-light source is used. [ABSTRACT FROM AUTHOR]

We study how one-particle correlations transfer to manifest as two-particle correlations in the context of parametric down-conversion (PDC), a process in which a pump photon is annihilated to produce two entangled photons. We work in the polarization degree of freedom and show that for any two-qubit generation process that is both trace-preserving and entropy-nondecreasing, the concurrence C(ρ) of the generated two-qubit state ρ follows an intrinsic upper bound with C(ρ) ≤ (1 + P)/2, where P is the degree of polarization of the pump photon. We also find that for the class of two-qubit states that is restricted to have only two nonzero diagonal elements such that the effective dimensionality of the two-qubit state is the same as the dimensionality of the pump polarization state, the upper bound on concurrence is the degree of polarization itself, that is, C(ρ) ≤ P. Our work shows that the maximum manifestation of two-particle correlations as entanglement is dictated by one-particle correlations. The formalism developed in this work can be extended to include multiparticle systems and can thus have important implications towards deducing the upper bounds on multiparticle entanglement, for which no universally accepted measure exists. [ABSTRACT FROM AUTHOR]