Table of contents

We review the principles and some recent advances in the theory of coherent control of molecular processes and discuss some of its experimental realizations. Amongst the topics discussed are: bichromatic and pump-dump control; the interference between N-photons and M-photon processes; the optical conversion of a mixture of left- and right-handed chiral molecules into an ensemble containing molecules of the handedness of choice; control of collisional processes; control over chaotic dynamics; effects of decoherence; the solution of the non-degenerate quantum control problem; and control over spontaneous emission and other decay processes.

The prediction that black holes radiate due to quantum effects is often considered one of the most secure in quantum field theory in curved space-time. Yet this prediction rests on two dubious assumptions: that ordinary physics may be applied to vacuum fluctuations at energy scales increasing exponentially without bound; and that quantum-gravitational effects may be neglected. Various suggestions have been put forward to address these issues: that they might be explained away by lessons from sonic black hole models; that the prediction is indeed successfully reproduced by quantum gravity; that the success of the link provided by the prediction between black holes and thermodynamics justifies the prediction.

This paper explains the nature of the difficulties, and reviews the proposals that have been put forward to deal with them. None of the proposals put forward can so far be considered to be really successful, and simple dimensional arguments show that quantum-gravitational effects might well alter the evaporation process outlined by Hawking. Thus, a definitive theoretical treatment will require an understanding of quantum gravity in at least some regimes. Until then, no compelling theoretical case for or against radiation by black holes is likely to be made.

The possibility that non-radiating `mini' black holes exist should be taken seriously; such holes could be part of the dark matter in the Universe. Attempts to place observational limits on the number of `mini' black holes (independent of the assumption that they radiate) would be most welcome.

One of the most surprising consequences of quantum mechanics is the entanglement of two or more distance particles. Even though there are still questions regarding the fundamental issues of quantum theory, quantum entanglement has started to play important roles in practical engineering applications such as quantum information processing, quantum metrology, quantum imaging and quantum lithography. Two-photon states have been the most popular entangled states in fundamental and applied research. Using spontaneous parametric down conversion as an example, this review introduces the concept of biphoton wavepacket and emphasizes the very different physics associated with the entangled two-photon system (pure state) and with the `individual' subsystems (statistical mixture). Experimental approaches for Bell state preparation, pumped by continous wave and ultrashort pulse are discussed.

Particle accelerators of higher and higher energy and intensity are required, as the investigation of subatomic matter needs to be pursued with higher and higher resolving power. To keep pace with this need while keeping physical dimensions and the cost of accelerator installations affordable, ever new ideas and technologies must be devised. After a brief general introduction and a summary of accelerator physics basics, we review the main lines of development of state of the art installations recently built, in construction or on the drafting board. New physics and technology challenges they pose and main topics still open to further research and development are also outlined.