On the correction of anomalous phase oscillation in entanglement witnesses using quantum neural networks

Entanglement of a quantum system depends upon relative phase in complicated ways, which no single measurement can reflect. Because of this, entanglement witnesses are necessarily limited in applicability and/or utility. We propose here a solution to the problem using quantum neural networks. A quantum system contains the information of its entanglement; thus, if we are clever, we can extract that information efficiently. As proof of concept, we show how this can be done for the case of pure states of a two-qubit system, using an entanglement indicator corrected for the anomalous phase oscillation. Both the entanglement indicator and the phase correction are calculated by the quantum system itself acting as a neural network

A quantum neural network computes its own relative phase

Complete characterization of the state of a quantum system made up of subsystems requires determination of relative phase, because of interference effects between the subsystems. For a system of qubits used as a quantum computer this is especially vital, because the entanglement, which is the basis for the quantum advantage in computing, depends intricately on phase. We present here a first step towards that determination, in which we use a two-qubit quantum system as a quantum neural network, which is trained to compute and output its own relative phase

Long-Term Impacts of the Oportunidades Conditional Cash Transfer Program on Rural Youth in Mexico

This paper studies the long-term effects of participation in the Mexican Oportunidades program on a variety of outcomes and behaviors of rural youth in Mexico. It analyzes data from a social experiment, which randomly phased-in the program in rural Mexican villages. In 1997, 320 villages (the treatment group) were randomly selected for early incorporation into the program and 186 villages (the control group) were designated as a control group to be incorporated eighteen months later. This paper examines whether differential exposure to the program significantly impacted educational attainment, labor market outcomes, marriage, migration and cognitive achievement of youth. The results show positive impacts of longer exposure on grades of schooling attained, but no effects on achievement tests. With respect to work, we find an overall reduction in work for male youth.