The developmentanduseof variationalprinciplesfor variousproblemsin atomic physicsby Larry Spruchandhis collaboratorsover the last forty yearsis reviewed anda roadmapprovidedfor theirpublications.… Expand

Quantum discord, a kind of quantum correlation, is defined as the difference between quantum mutual information and classical correlation in a bipartite system. In general, this correlation is… Expand

Infinitesimal rotations and angular momentum frame reversal and complex conjugation standard r-transformation matrices and their applications reduction of direct products (addition of angular… Expand

A compact derivation is given for propagators of a wide class of time-dependent Hamiltonians that describe coupled spin (``qubit'') pairs. As many as eight of the 16 operators in the system, each… Expand

Geometric phases are important in quantum physics and are now central to fault-tolerant quantum computation. For spin 1/2, the Bloch sphere S{sup 2}, together with a U(1) phase, provides a complete… Expand

We review topics of current interest in the physics of electronic, atomic and molecular scattering in the vicinity of thresholds. Starting from phase space arguments, we discuss the modifications of… Expand

that for N qubits, with an exponential increase in the number of parameters, that similar subsets of N-qubit X states with fewer parameters but still embracing most of the phenomena of interest will… Expand