I am trying to transform this matrix into a combination of quantum gates but I cannot find any such functionality on Qiskit or anywhere else. I have tried to use Quirk but I do not understand it. $\begin{bmatrix}0 & 1 & 0 & 0\\1 & 0&0&0\\0 & 0&0&1\\0 & 0&1&0\end{bmatrix}$

Lets consider there is channel between Alice and Bob, sequered with quantum cryptography. To put it simple, Alice is left, Bob is right and the quantum states are 'up' ~ U and 'down' ~ D. Alice and Bob generates pair of bounded particles ,always one u one d but you dont know wtigth one flye...

In special relativity, taking into account time-dilation factor, what is the formula for calculating time-travel past as opposed to "future"? I have the calculations for future thanks to another post. I'm looking for "past" only. Thanks

I am in the process of understanding a proof. First, the following is said there: $$H\begin{pmatrix}1\\0\\\vdots\\0\end{pmatrix}=\frac{1}{\sqrt{N}}\begin{pmatrix}1\\1\\1\\1\end{pmatrix}$$ This is clear so far, because the Hadamard transformation applied to the state $|0...0\rangle$ produces an ...

Let $(V, \mathbb{C})$ be a complex - valued vector space. Let $A$ be any linear operator acting on this vector space. Suppose that the basis set $B = \{|v\rangle_{k}\}_{k=1}^{n}$ is a basis set for $(V, \mathbb{C})$. Then, the linear operator $A$ may be written as $A = \sum_{k=1}^{n}A_{kj}|v_{k}\...