Editorial

The principles of quantum-mechanical measurements are a key issue in the foundation of modern physics. A beautiful consequence of these is the concept of Quantum Nondemolition (QND) measurements. Such measurements permit, in principle, to measure particular observables of a quantum system with unlimited precision, leaving their temporal evolution undisturbed. The application of QND measurements may play an important role in future high-sensivity experiments.Experimental QND measurements require appropriate measurements schemes and apparats, whose development took place in the past few years, thanks to strong progress in ultra-low noise mechanical, electronic and optical detection techniques, coherent light sources, and nonlinear optical systems. At present, interest is focused on measurements of mechanical observables, such as displacement of macroscopic masses and of intensity or phases of electomagnetic field modes in the optical spectral range.This special issue contains original papers on theory and experiments of QND measurements. Recent experimental developments are presented, and proposals and analyses of novel QND schemes are made.The issue focuses on contributions presented at the Workshop on QND Measurements, held March 27–29, 1996, on the Island of Reichenau, Lake Constance (Germany). The workshop was made possible through a generous grant from the Directorats General XII for Sciences, Research and Development of the European Commission.We thank Dr. W. Petrich for his help in preparing this special issue.     

Editorial

<正>In celebration of the 85th anniversary for the Institute of Physics,Chinese Academy of Sciences,we publish this special issue of Science China-Physics,MechanicsAstronomy,which serves as a venue to display a small part of the research activities currently undertaken by us.This special issue contains one essay and 19 research articles.The prelude by the director of the     

Editorial

This topical issue collects contributions to the interdisciplinary study of the interacting global systems of public health, energy production, and climate change, in order to provide physicists with an opportunity to explore these fields of application of great societal importance.