Quantum-enhanced data science, also known as quantum machine learning (QML), is of growing interest as an application of near-term quantum computers. Variational QML algorithms have the potential... Show moreQuantum-enhanced data science, also known as quantum machine learning (QML), is of growing interest as an application of near-term quantum computers. Variational QML algorithms have the potential to solve practical problems on real hardware, particularly when involving quantum data. However, training these algorithms can be challenging and calls for tailored optimization procedures. Specifically, QML applications can require a large shot-count overhead due to the large datasets involved. In this work, we advocate for simultaneous random sampling over both the dataset as well as the measurement operators that define the loss function. We consider a highly general loss function that encompasses many QML applications, and we show how to construct an unbiased estimator of its gradient. This allows us to propose a shot-frugal gradient descent optimizer called Refoqus (REsource Frugal Optimizer for QUantum Stochastic gradient descent). Our numerics indicate that Refoqus can save several orders of magnitude in shot cost, even relative to optimizers that sample over measurement operators alone. Show less
Nowadays, urban-rural connections are accelerating in sub-Saharan Africa resulting in agricultural transformations, which in turn lead to the transformation of rural livelihoods. This paper... Show moreNowadays, urban-rural connections are accelerating in sub-Saharan Africa resulting in agricultural transformations, which in turn lead to the transformation of rural livelihoods. This paper examines agricultural transformations in the Dodoma Region, Tanzania, and their impact on local rural livelihoods. Triggered by transportation development and rising demand for agricultural produce on the national and international level, the transformation of rural livelihoods on the village level entails: the application of more advanced methods and organisation of agricultural production; the increased use wage-labour; considerably higher agricultural revenues; a distinct rise of livelihoods partly or exclusively based on small-scale industry, petty trade and other businesses; and a distinctively higher level of incomes and consumption. Show less
The circular economy has become a useful concept in sustainable resource management and an area of research that influences business and policy. The successful application of the circular economy... Show moreThe circular economy has become a useful concept in sustainable resource management and an area of research that influences business and policy. The successful application of the circular economy benefits from extensive engagement with the body of scientific knowledge that brought it about, and which offers many relevant methods and findings. This white paper promotes such engagement by presenting 10 insights from the field of industrial ecology; each insight presents critical concepts, challenges, or opportunities for the circular economy stakeholders. Show less
