Quick Lookup

Quick Lookup is the fastest route into the reference layer. Use it when you need a compact formula, a symbol meaning, the canonical home for a concept, or a reminder about which convention is being used.

This section does not replace full explanations. Each entry should point to the canonical teaching page, derivation, model page, or convention page.

Main Routes

Core Formulas Index collects the formulas most often needed across the site, with assumptions and canonical links.
Core Concepts Index lists high-frequency concepts and their canonical homes.
Common Symbols Index records default symbol meanings, common collisions, and convention warnings.
Most-Used Hamiltonians routes common Hamiltonian expressions to assumptions, scales, reference cards, and canonical model pages.
Common Convention Translations crosswalks common unit, Fourier, inner-product, tensor-ordering, spin, and measurement convention changes.
Student Quick Reference gives a compact undergraduate problem-solving checklist.
Researcher Quick Reference gives a compact audit sheet for conventions, source fit, rigor flags, approximations, and bridge topics.

What A Quick Entry Should Answer

Every useful quick entry should answer:

What is the object or formula?
What assumptions are required?
Which convention is being used?
Where is the canonical explanation?
Where is the derivation or worked example?
What is the most common mistake?

If any of those answers need more than a few lines, the entry should link out rather than grow into a second textbook page.

Current Priority

The launch priority is:

formulas needed for Core Formalism and Wave Mechanics;
symbols that appear in frontmatter, equations, and tables;
concepts with many cross-links, such as state, observable, Hamiltonian, Hilbert space, wavefunction, Born rule, commutator, and density operator;
Hamiltonians for the free particle, square well, harmonic oscillator, two-level system, and spin systems;
convention translations and student-facing survival sheets;
bibliography pages for standard textbooks and classic papers.

Reference Discipline

Quick Lookup pages should be dense but not cryptic. A formula without assumptions is unsafe. A symbol without convention notes invites errors. A concept entry without canonical links duplicates content.

When in doubt, prefer a shorter entry with better links.

References

R. Shankar, Principles of Quantum Mechanics, 2nd ed., Springer, 1994.
J. J. Sakurai and J. Napolitano, Modern Quantum Mechanics, 3rd ed., Cambridge University Press, 2020.
D. J. Griffiths and D. F. Schroeter, Introduction to Quantum Mechanics, 3rd ed., Cambridge University Press, 2018.
M. A. Nielsen and I. L. Chuang, Quantum Computation and Quantum Information, Cambridge University Press, 2010.