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1500 questions
23
votes
1 answer
What is the intuition behind quantum t-designs?
I started reading about Randomized Benchmarking (this paper, arxiv version) and came across "unitary 2 design."
After some googling, I found that the Clifford group being a unitary 2 design is a specific case of "Quantum t-design."
I read the…
Blackwidow
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23
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Is there a closure property for the entire Clifford hierarchy?
TL;DR
Is the entire Clifford hierarchy (as opposed to any one level), a group?
Background.
The Clifford hierarchy (on $n$ qubits), is a collection of nested subsets $\mathcal C^{(1)} \subset \mathcal C^{(2)} \subset \mathcal C^{(3)} \subset \cdots…
Niel de Beaudrap
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23
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What is the difference between transmon and Xmon qubits?
Transmon and Xmon qubits are two types of superconducting charge qubits that seem to be often used in superconducting quantum devices.
However, I wasn't able to easily find direct comparisons between them.
The Xmon architecture seems (1304.2322) to…
glS
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23
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1 answer
How does magic state distillation overhead scale compare to quantum advantages?
I'm interested in the model of quantum computation by magic state injection, that is where we have access to the Clifford gates, a cheap supply of ancilla qubits in the computational basis, and a few expensive-to-distill magic states (usually those…
Emily Tyhurst
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What protocols have been proposed to implement quantum RAMs?
The crucial role of random access memories (RAMs) in the context of classical computation makes it natural to wonder how one can generalise such a concept to the quantum domain.
Arguably the most notable (and first?) work proposing an efficient QRAM…
glS
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22
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11 answers
Is my background sufficient to start quantum computing?
I am a first-year undergraduate electrical engineering student. I want to study quantum computing and quantum AI in the future and also possibly work on building quantum computers.
I have finished Strang's Introduction to Linear Algebra twice and…
Huseyin Okan Demir
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6 answers
Tools for creating quantum circuit diagrams
What tools exist for creating quantum circuit diagrams and exporting them as images? Preferably one which runs in Windows, or even better one which runs in the web browser.
ahelwer
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4 answers
What is a list of research journals publishing quantum computing articles?
Can anyone give me a list of different research journals that has quantum computing articles that I can use.
Ibukun Oladunjoye
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4 answers
Why are half angles used in the Bloch sphere representation of qubits?
Suppose we have a single qubit with state $| \psi \rangle = \alpha | 0 \rangle + \beta | 1 \rangle$. We know that $|\alpha|^2 + |\beta|^2 = 1$, so we can write $| \alpha | = \cos(\theta)$, $| \beta | = \sin(\theta)$ for some real number $\theta$. …
wanderingmathematician
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2 answers
How do you implement the Toffoli gate using only single-qubit and CNOT gates?
I've been reading through "Quantum Computing: A Gentle Introduction", and I've been struggling with this particular problem. How would you create the circuit diagram, and what kind of reasoning would lead you to it?
Lucas Myers
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3 answers
Toffoli gate as FANOUT
I was searching for examples of quantum circuits to exercise with Q# programming and I stumbled on this circuit:
From: Examples of Quantum Circuit Diagrams
- Michal Charemza
During my introductory courses in quantum computation, we were taught…
D-Brc
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22
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1 answer
An impossible quantum adder claimed by a journal article?
In Quantum adder of two states that are themselves superpositions, I asked:
I have two states $|a\rangle = \frac{1}{\sqrt N}\sum_{i=0}^{N-1}|i\rangle|a_i\rangle$ and $|b\rangle = \frac{1}{\sqrt N}\sum_{j=0}^ {N-1} |j\rangle|b_j\rangle$,…
Paulske
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22
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6 answers
Quantum states are unit vectors... with respect to which norm?
The most general definition of a quantum state I found is (rephrasing the definition from Wikipedia)
Quantum states are represented by a ray in a finite- or infinite-dimensional Hilbert space over the complex numbers.
Moreover, we know that in…
Adrien Suau
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Is the Pauli group for $n$-qubits a basis for $\mathbb{C}^{2^n\times 2^n}$?
The $n$-fold Pauli operator set is defined as $G_n=\{I,X,Y,Z \}^{\otimes n}$, that is as the set containing all the possible tensor products between $n$ Pauli matrices. It is clear that the Pauli matrices form a basis for the $2\times 2$ complex…
Josu Etxezarreta Martinez
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22
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5 answers
What is a Bacon-Shor code and what is its significance?
I'm at the AQC conference at NASA and everybody seems to suddenly be talking about the Bacon-Shor code but there is no Wikipedia page and the pdf that I gave a link to does not really explain what it is and how it works.
How does it compare to the…
user1271772 No more free time
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