# Quantum computing 101 for non-physicists¶

Warning

This is an unfinished draft.

Quantum computing has become a buzzword nowadays. Both big tech companies and startups are competing to bring quantum computing services to the market. Despite the increasing R&D effort in industry and academia, quantum computing is mysterious because both quantum mechanics and computing theory are lesser-known topics. And most online materials are written for physics majors.

The purpose of this book is to introduce quantum computing to non-physicists. I try to focus on the principles and ideas to the best of my knowledge, and not get trapped too much in detailed calculations. If the quantum computing field is a state park, then this book is a map of a trail.

The maths are kept easy and analogies/comparisons are often used. The reader is assumed to know linear algebra and probability theory. Specifically, the following equations should look familiar

- \(\mathbf f = m\mathbf a\)
- \(\frac{d}{dt}\mathbf p = R\mathbf p\)
- \(A \mathbf x = \lambda \mathbf x\)
- \(e^{i\theta} = \cos\theta + i\sin\theta\)

What this book doesn’t do:

- It doesn’t teach quantum mechanics systematically.
- It doesn’t describe physical implementations of quantum computers.

As for notation, I use upper case letter for matrix, bold and lower case letter for vector, and lower case letter for scalars. For simplicity, Planck constant is omitted in all formulas.

Note

I use these boxes to give heads up.

See also

I use these boxes for optional materials.

The book should be read in linear order.

While preparing the materials, I follow several principles to keep my sanity

- Concise is better than verbose.
- Concrete is better than abstract.
- Goal-oriented is better than rambling.
- Comprehensive is better than referencing.

Please email me if you find errors, or have comments and suggestions. Feel free to create pull requests on GitHub with revision too.