Attila Kun
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2 answers
4 votes
687 views
Can classical linear algebra solvers implement quantum algorithms with similar speed-ups?
Accepted answer
5 votes

The complexity that you are glossing over is that in the general case you need to store $2^n$ complex amplitudes to even represent an $n$ qubit system classically. Therefore, for a quantum computer of ...

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1 answers
3 votes
95 views
Why can I use the Sum of Eigenvectors for Phase Estimation in Shor
Accepted answer
3 votes

As you say, we would be able to use phase estimation if we knew the eigenvector $|u_s \rangle$ that depends on the order $r$ and the integer $s$ which is $0 \leq s \leq r - 1$. However, we don't know ...

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4 answers
10 votes
4k views
Is there any online Bloch sphere simulator?
2 votes

Let me plug my pet project: https://attilakun.net/bloch It allows you to enter arbitrary 2x2 matrices and visualize how the quantum state is affected by them. In the below example the red arc shows ...

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1 answers
5 votes
245 views
Decomposition of any 2-level matrix into single qubit and CNOT gates
1 votes

$\newcommand{\bra}[1]{\left<#1\right|} \newcommand{\ket}[1]{\left|#1\right>}$Consider the following linear operator: $$ U = \left[ \begin{matrix} a & 0 & 0 & 0 & 0 & 0 & ...

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2 answers
5 votes
341 views
Problem 2.2 in Nielsen & Chuang - Properties of the Schmidt number
1 votes

$\newcommand{\bra}[1]{\left<#1\right|} \newcommand{\ket}[1]{\left|#1\right>} \newcommand{\sch}[1]{\operatorname{Sch}\left( #1 \right)} \newcommand{\cases}[3]{ #1 = \begin{cases} #2 \hspace{1em} \...

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