This book is a collection of lecture notes and contributions in “Summer School on Diversities in Quantum Computation/Information” held on 1–5 August, 2010 at U-Community Hotel, Higashi-Osaka, Japan. Lecturers are world class authorities in respective areas in quantum information and quantum computing including physics, mathematics, chemistry and information science. They lectured on cutting-edge research frontiers where they are currently working, including quantum error correction, relativistic quantum information, quantum computing of link polynomials, quantum algorithms, etc. Each lecture note is written in a self-contained manner so that it may be used as a textbook for one semester graduate course or advanced undergraduate course. Contributions report current research subjects also in a self-contained manner. We believe that these articles are accessible to the readers form various disciplines. Contents:Matrix Techniques in Quantum Information Science (C-K Li)Untying Knots by NMR: Experimental Implementation of an Exponentially Fast Quantum Algorithm for Approximating the Jones Polynomial (R Marx)Quantum Algorithms for Problems in Number Theory, Algebraic Geometry, and Group Theory (W van Dam and Y Sasaki)Lecture Series on Relativistic Quantum Information (I Fuentes)Systematic Construction of Bell-Like Inequalities and Proposal of a New Type of Test (S Tanimura)Hybrid Quantum Annealing for Clustering Problems (S Tanaka)Theory of Macroscopic Quantum Tunneling in Two-Gap Superconductors: Corrections from Leggett's Modes (Y Ota, M Machida and T Koyama) Readership: Graduate students and researchers in physics, mathematics, informatics and computer science. Accessible to advanced undergraduate students. Keywords:Quantum Information;Quantum Computer;Entanglement;Non-Classical Correlation;Number Theory;Coding Theory