  One area of physics education research has focused on the nature of
ontologies (mental categorizations of concepts, substances and processes), and
how they might be used to gain insight into student thinking when learning
classical physics. There has been some debate about whether student and expert
ontologies in classical contexts should be thought of as stable cognitive
structures or dynamic cognitive processes, and what implications these
different perspectives have for instruction. We extend this discussion of
ontologies and their role in learning and cognition to the context of quantum
physics, by first considering various types of epistemological and ontological
commitments exhibited by experts in their descriptions of quantum phenomena.
Excerpts from student interviews and responses to survey questions are used to
demonstrate the contextual nature of students' quantum ontologies, which can be
best understood within a resources framework. Instructional implications are
discussed, including a brief description of a modern physics curriculum
designed to explicitly attend to student ontologies.
