Questions tagged [fault-tolerance]

For questions about achieving (almost) perfect logical operations with imperfect gates. The tag also applies to questions about the amount of tolerable noise in a quantum circuit, as well as designing circuits to prevent errors from spreading.

113 questions
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Why or how is 'cat' state preparation via a C-not-not operation not fault tolerant?

On p490 of Nielsen and Chuang, 2010 the authors say that the preparation of the 'cat' state ($|000\ldots 0\rangle+|111\ldots 1\rangle$) is not Fault Tolerant. Below is my mock up of the diagram they draw for the preparation ($H$ and $C$-not-not *)…
6
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1 answer

Why can't we implement fault-tolerant single qubit rotations continuously?

My understanding is that in order to implement single-qubit rotations on logical fault-tolerant qubits one has to do smth like discretizing rotations and using $T$ gates. So, is it the case that given perfect single-qubit rotations of physical…
mavzolej
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