Top new questions this week: |
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Does there exists super-polynomial quantum advantage for decoding certain linear codes?Syndrome decoding is NP-complete problem [page 6 of this reference]. There are some special linear codes for which we know efficient classical decoding algorithms, such as Reed-Solomon, LDPC and etc. ...
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Visualise Hadamard gate as addition of $x$ and $z$ gateI try to immagine the hadamard gate on a bloch sphere and it is obvious that it is the sum of the pauli $x$ and $z$ gate matrices. So that means we rotate the "vector" around the x axe and ...
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stim: why would order of CNOT operations affect detectorsI have two circuits (below) : first works fine (no complaints from stim); second comes back with a "non-deterministic detector" error. The difference between the two circuits is that the ...
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Why is the fastest quantum time complexity of unstructured search O(sqrt(n))?Recently, I have watched video on 3Blue1Brown about Grover's algorithm. He give an example that: To find a secret number in the range from 0 to n−1, you can query a hidden function that returns “true”...
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Greatest hits from previous weeks: |
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What makes quantum computers so good at computing prime factors?One of the common claims about quantum computers is their ability to "break" conventional cryptography. This is because conventional cryptography is based on prime factors, something which is ...
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What is a Haar random quantum state?Can somebody please explain me what is a Haar random state? I am not able to find any friendly resource to read about it.
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How to input 2 qubits in 2 Hadamard gates?Let's say we have a circuit with $2$ Hadamard gates: Let's take the $|00\rangle$ state as input. The vector representation of $|00\rangle$ state is $[1 \ 0 \ 0 \ 0]$, but this is the representation of ...
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How do I add 1+1 using a quantum computer?This can be seen as the software complement to How does a quantum computer do basic math at the hardware level? The question was asked by a member of the audience at the 4th network of the Spanish ...
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What countries are leading this "Global Quantum Computing Race"?The terms Quantum Computing Race and Global Quantum Computing Race have been used in the press and research communities lately in an effort to describe countries making investments into a "battle" to ...
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Evaluating expectation values of operators in QiskitI'm wondering how in Qiskit one can calculate the expectation value of an operator given as a WeightedPauli (or, at least, of a single ...
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What do the off-diagonal elements of a density matrix physically represent?For simplicity, let's take a density matrix for a single qubit, written in the $\{|0\rangle,|1\rangle\}$ basis: $$ \rho = \begin{pmatrix} \rho_{00} & \rho_{01} \\ \rho_{10}^* & 1-\rho_{00} \...
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