*64%*:**Student difficulties with determining expectation values in quantum mechanics***58%*:**Investigating student understanding of basic quantum mechanics in the context of time-dependent perturbation theory***44%*:**Investigating Student Difficulties with Dirac Notation***44%*:**Student understanding of potential, wavefunctions and the Jacobian in hydrogen in graduate-level quantum mechanics***44%*:**Enhancing student visual understanding of the time evolution of quantum systems***41%*:**Student difficulties with quantum states while translating state vectors in Dirac notation to wave functions in position and momentum representations***40%*:**Improving studentsâ€™ understanding of quantum measurement. I. Investigation of difficulties***40%*:**Student difficulties with representations of quantum operators corresponding to observables***40%*:**Investigating student use of a flexible tool for simulating and visualizing quantum mechanics***38%*:**Investigating Student Understanding of Perturbation Theory and the Inner Products of Functions***38%*:**Surveying students' understanding of quantum mechanics in one spatial dimension***37%*:**Student understanding of quantum mechanical expectation values in two different curricula***36%*:**Student difficulties in learning quantum mechanics***36%*:**Student Difficulties in Understanding Probability in Quantum Mechanics***36%*:**University students' reasoning on physical information encoded in quantum state at a point in time***36%*:**The use of ACER to develop and analyze student responses to expectation value problems***36%*:**Student Understanding of Period in Introductory and Quantum Physics Courses***35%*:**Analogous Patterns of Student Reasoning Difficulties in Introductory Physics and Upper- Level Quantum Mechanics***35%*:**Using student-generated content to engage students in upper-division quantum mechanics**