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1500 questions
7
votes
2 answers
How to construct the "Inversion About the Mean" operator?
It seems like it should be simple, based on how Nielsen and Chuang talk about it, but I cannot seem to correctly implement the Inversion About the Mean operator ($2|\psi\rangle \langle\psi| - \mathcal{I}$) that is used in the Grover search…
nikojpapa
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7
votes
2 answers
Analyzing the three-polarizing-filter experiment as a quantum circuit
In the three-polarizing-filter experiment, two orthogonal polarizing filters block all light but then allow some amount when a third polarizing filter is placed oriented at a 45 degree angle between them.
Can we analyze this experiment through terms…
ahelwer
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7
votes
1 answer
Decomposition of an arbitrary 1-qubit gate into a specific gateset
Any 1-qubit special gate can be decomposed into a sequence of rotation gates ($R_z$, $R_y$ and $R_z$). This allows us to have the general 1-qubit special gate in matrix form: …
Ntwali B.
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7
votes
2 answers
How can I get access to IBM Q 20 Tokyo and IBM Q 20 Austin?
How can I get access to IBM Q 20 Tokyo and IBM Q 20 Austin?
In the Q- experience site there is written that the access is for IBM clients only and in the profile there is a "promotional code" that you need to put to gain access to those chips.
How I…
Daniel Vainshtein
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7
votes
1 answer
Is there a relation between the factorisation of the joint conditional probability distribution and Bell inequality?
[I'm sorry, I've already posted the same question in the physics community, but I haven't received an answer yet.]
I'm approaching the study of Bell's inequalities and I understood the reasoning under the Bell theorem (ON THE EINSTEIN PODOLSKY…
LadyOfShalott
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7
votes
1 answer
Is there a classical limit to quantum computing?
Why are quantum computers scalable?
With the subjects of spontaneous collapse models and decoherence in mind, it seems to me that the scalability of quantum computers is something which is not only physically difficult to achieve but also…
Jake Xuereb
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7
votes
3 answers
Example of Hamiltonian Simulation solving interesting problem?
Hamiltionian Simulation (= simulation of quantum mechanical systems) is claimed to be one of the most promising applications of a quantum computer in the future.
One of the earliest – and most important – applications of a quantum
computer is…
JanVdA
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7
votes
2 answers
What is the smallest quantum circuit to produce two-qubit state (a,b,b,b)?
How can I synthesis a two-qubit quantum state of the state vector (a,b,b,b) using basic quantum-gate circuit (arbitrary single-qubit rotation and controlled $Z$ gate)? And further, can I know a given circuit is the simplest?
cmc
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7
votes
1 answer
Specialized/hardcoded modular exponentiation circuit for Shor's
While researching to implement Shor's algorithm, I came across the following curcuit diagram (diagram 1).
And while researching for how to implement the U operator, I came across the following circuit diagram (diagram 2).
The circuit in diagram 2…
shrini1000
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7
votes
0 answers
Complexity of a superposition of two random circuits
$\def\ket#1{|{#1}\rangle}$
Question
What is the minimum number of gates required to create the $N$-qubit state $\ket{\psi} = \frac{\ket{a} + \ket{b}}{\sqrt2}$ from the all-zeroes state, where one term in the superposition, $\ket{a}$, can be created…
Jordan Taylor
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7
votes
4 answers
How to re-create the following circuit image?
What would be the best way to re-create the following image of the HHL quantum circuit without compromising on image quality (the image is from this review paper)?
Using qasm2circ I can create the basic circuit. But I don't know any good…
Sanchayan Dutta
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7
votes
1 answer
Can we process infinite matrices with a quantum computer?
Can we process infinite matrices with a quantum computer? If so, how can we do that?
Hyeonseo Yang
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7
votes
3 answers
What is the difference between $\vert 0 \rangle + \vert 1 \rangle$ and $\vert 0 \rangle \langle 0 \vert + \vert 1 \rangle \langle 1 \vert$?
In a discussion with Jay Gambetta on the QISKit Slack channel, Jay told me that "T2 is the time that $\vert 0 \rangle + \vert 1 \rangle$ goes to $\vert 0 \rangle \langle 0 \vert + \vert 1 \rangle \langle 1 \vert$".
My question is: what is the…
Adrien Suau
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7
votes
3 answers
Is entanglement an operation or a stored state for qubits?
I am going through this video of Quantum Computing for Computer Scientists. I am not able to understand the entanglement state of qubits.
Is entanglement just an operation, or is it a state which can be stored. If it's a state which is stored then…
rusty
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7
votes
1 answer
Solving linear systems represented by NxN matrices with N not power of 2
As far as I have seen, when it comes to solving linear systems of equations it is assumed to have a matrix with a number of rows and columns equal to a power of two, but what if it is not the case?
If for instance I have the equation $Ax=b$ where A…
FSic
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