# 量子计算入门

(Suspended due to priority change.)

## Resources

### Books

#### Quantum Computing Since Democritus

But if quantum mechanics isn't physics in the usual sense - if it's not about matter, or energy, or waves, or particles -then what is it about? From my perspective, it's about information and probabilities and observables, and how they relate to each other.

There are two ways to teach quantum mechanics. The first way - which for most physicists today is still the only way - follows the historical order in which the ideas were discovered... The second way to teach quantum mechanics eschews a blow-by-blow account of its discovery, and instead starts directly from the conceptual core - namely, a certain generalization of the laws of probability to allow minus signs )and more generally, complex numbers).

Quantum mechanics is what you would inevitably come up with if you started from probability theory, and then said, let's try to generalize it so that the numbers we used to call "probabilities" can be negative numbers. As such, the theory could have been invented by mathematicians in the nineteenth century without any input from experiment. It wasn't, but it could have been.

More often than not, the only reason we need experiments is that we're not smart enough.

#### Q is for Quantum

PART 1 部分，对比经典计算机中的与或非门，清晰地描述了量子门(PETE BOX)的特性。

1. superposition / misty state
2. interfere
3. collision

PART 2 部分，用一个很形象的例子（心灵感应?）讲清楚了一个很有意思的现象：

Entanglement

PART 3展开讨论了什么是REALITY，这部分相比前两部分理解得没那么透彻。照惯例，附上两篇书评：