  Distance measures are indispensable tools in quantum information processing
and quantum computing. This since they can be used to quantify to what extent
information is preserved, or altered, by quantum processes. In this paper we
propose a new distance measure for mixed quantum states, that we call the
dynamic distance measure, and show that it is a proper distance measure. The
dynamic distance measure is defined in terms of a measurable quantity, which
make it very suitable for applications. In a final section we compare the
dynamical distance measure with the well-known Bures distance.
