Abstract

Quantum trajectories of state vectors can be used to describe open systems that otherwise can only be described using a density matrix. Besides the numerical advantage, quantum trajectories provide insight in the actual evolution of a system under continuous observation. Two distinct methods are usually considered, the quantum-jump method,¹ associated with direct photodetection, and the quantum- state diffusion (QSD) method,² associated with homodyne or heterodyne mixing.

© 1998 Optical Society of America