Quantum-Theoretical Basis. Density Matrix

Mohammad Mirhosseini, Omar S. Magaña‐Loaiza, Seyed Mohammad Hashemi Rafsanjani +3 more

We theoretically propose and experimentally demonstrate a method for directly measuring the density matrix of an unknown quantum system in the basis of azimuthal angle. We apply our method for characterizing 7-dimensional pure and mixed superpositions of orbital-angular-momentum modes.

Apoorva Patel

Michitoshi Hayashi, Ruey‐Feng Chang, Kuo Kan Liang +6 more

Basic theoretical treatments of quantum beats are presented using the effective Hamiltonian method and the density matrix method. To describe the states involved in quantum beats, the molecular-eigen state basis set and the zeroth order basis set are introduced. Based on these basis sets for the two-state model, the condition under which molecular coherence can be created is discussed.

Karl Blum

Iaakov Exman, Alexey V. Nechaev

Quantum Software Models is a theoretical framework to systematically design and analyze any software system -be it quantum, classical or hybrid -representing it by a design Density Matrix.Recently, we have demonstrated a top-down approach, to decompose a whole software system Density Matrix into modules, using basis vector projectors of the Matrix.However, it would be even more natural to have a systematic bottom-up procedure, to compose a whole software system Density Matrix, given a set of well-designed software module matrices, taken as sub-systems.This is exactly the paper's purpose.The result obtained: the whole software system Density Matrix is a perfect Direct Sum of module density matrices.This result yields clear software design benefits: it is bidirectional, one can traverse the software system hierarchy top-down or bottom-up, in particular, gradually building up the whole system from verified correct modules, assured by spectral decoupling techniques.The claim is formally validated and is illustrated by software system studies.