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Newest 'quantum-gate' Questions - Quantum Computing Stack Exchange
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Learn more about TeamsQuestions tagged [quantum-gate]
For questions regarding usage, performance, implementation, application or theory related to quantum gates.
1,869 questions
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1
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Creating T gadgets
Consider an arbitrary Clifford circuit, terminating in a last layer of $T$ gates. Is it possible to construct a $T$ gadget using post selection in this setup?
If we have $T$ gates in the beginning, ...
1
vote
1
answer
87
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does every quantum circuit have a "canonical form"
I'm reading through this recent survey paper and on page 18 it states that "every quantum circuit can be transformed into a canonical form : product of (clifford gate)* ($\pi/8$ pauli-product ...
0
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0
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20
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For an arbitrary unitary matrix, what is the most efficient decomposition method available?
I'm doing a comparison of decomposition methods for Hamiltonian matrices, and I use a time operator evolution to convert them to unitary matrices. I am just wondering, what is the most efficient ...
2
votes
1
answer
70
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does the standard form of a stabilizer code minimize the number of CX/CZ gates needed to encode it?
Given a stabilizer code, there are several ways to transform it to an equivalent code (same n,k,d). The "standard form" is one option and it seems to have lower CX and CZ gate count needed ...
1
vote
2
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85
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Quantum Gate Error Accumulation
It is usually said that quantum gate errors accumulate exponentially, so that a very high gate fidelity up to $99.99...\%$ is pursued.
I try to build a simple model that demonstrate this accumulation.
...
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0
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71
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Cost comparison for quantum incrementers with dirty ancillae: Gidney (1 dirty) vs. Gidney (n dirty)
Häner et al. (Fig. 5, arXiv:1611.07995) build an $n$-bit constant adder, citing Gidney’s $n$-dirty ancillae incrementer (2015) for the sub-routine. However, in arXiv:1706.07884, there is a controlled ...
1
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0
answers
26
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Why are Quantum Query Gates $U_f$ always permutation matrices? [duplicate]
I was reading through some material by IBM Quantum and it said the following in a section about Query Gates:
Here, our assumption is that $x \in \Sigma^{n}$ and $y \in \Sigma^{m}$ are arbitrary ...
1
vote
1
answer
105
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How is this CNOT simplification made?
How to perform gate simplifications to show that the two circuits above are equivalent?
2
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1
answer
73
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Possible label mismatch in Box 8.5 of Nielsen & Chuang — are ρ₂′ and ρ₃′ swapped?
I’ve been working through Box 8.5 of Nielsen & Chuang’s textbook (Quantum Computation and Quantum Information) related to single-qubit quantum process tomography.
Specifically, in equations (8.175)...
4
votes
2
answers
219
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Looking for a proof of a trace identity and (possibly) relationship to Kraus operators
$\DeclareMathOperator\PSU{PSU}\DeclareMathOperator\U{U}\DeclareMathOperator\SU{SU}\DeclareMathOperator\O{O}\DeclareMathOperator\SO{SO}\DeclareMathOperator\GL{GL}\DeclareMathOperator\ASL{ASL}\...
1
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1
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62
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In what order are noise channels applied relative to ideal gates in Qiskit and other quantum simulator frameworks?
I'm trying to understand how noise is applied in Qiskit and other quantum circuit simulation frameworks. While it's generally straightforward to specify which noise channels (e.g., depolarizing, ...
0
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2
answers
144
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Is equality $Z |0\rangle = |+\rangle$ true?
I had thought $Z |0\rangle = |0\rangle$ but... it seems not according to this quiz?
$Z |0\rangle = |+\rangle \; (???)$ - can this ever be true?
Source: https://stem.mitre.org/quantum/quantum-concepts/...
2
votes
0
answers
66
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Magic state distillation for gate outside the Clifford hierarchy
In the paper Super-Golden-Gates for PU(2) it is argued that, to achieve a set of exactly synthesizable gates which scales quickly with the number of non-Clifford gates and approximates arbitrary ...
0
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0
answers
20
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Computational cost of transpile 2^n X 2^n real valued unitary to quantum circuit
https://journals.aps.org/pra/abstract/10.1103/PhysRevA.93.032318
This paper seems showing boundary of number of CNOT gates to express general unitary.
How about for real-valued general unitary?
Is ...
0
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0
answers
84
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Quantum incrementer using conditionally clean dirty ancillae?
In Section 6 of arvix:2407.17966, the authors describe a way to create an n-qubit incrementer using $3n$ Toffoli and $\log^*(n)$ clean ancillae. Interestingly, Section 6 is the only one where there is ...
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programming × 205
quantum-algorithms × 180
quantum-circuit × 157
gate-synthesis × 135
entanglement × 105
linear-algebra × 89
ibm-q-experience × 85
pauli-gates × 82
error-correction × 80
unitarity × 78
universal-gates × 78
hadamard × 64
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