Introduction notes to quantum computing (continuously updated)

What is quantum ？

quantum ： A basic unit that cannot be subdivided . Photons are the basic unit of light that cannot be subdivided , You can call it quantum .

What is collapse ？

Collapse ： If you don't watch the cat in the box , The cat in the box is superimposed , The state of the cat will be determined after you observe it , Either dead or alive .

How are quantum states expressed ？

Quantum states can be expressed as state vectors （ The vector ） To describe .

Classification of state vector ？

Right arrow , Column vector

Left arrow , Row vector

A two-level system of energy ？

The low energy is called the ground state |g>

Those with high energy are called excited states |e>

Superposition state ？（ Pussy ）

Unitary transformation ？

Unitary transformation U It can be understood as a matrix

The nature of quantum state change ？

Do matrix transformation