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What is the difference between "Shot-Noise-Limit" and "Standard Quantum Limit"?
It seems that in a lot of papers in the field of quantum metrology, there are two terms Shot-Noise-Limit and Standard Quantum Limit which are frequently referred to. What's the difference between them, because it seems they all refer to the limit…
narip
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Decoherence of spin-entangled triplet-pair states in the solid state: local vs delocalized vibrations
The context: We are in the solid state. After a photon absortion by a system with a singlet ground state, the system undergoes the spin-conserving fission of one spin singlet exciton into two spin triplet excitons (for context, see The entangled…
agaitaarino
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A sample quantum algorithm, useful for demonstrating languages
I'm looking for a quantum algorithm which I can use to demonstrate the syntax of different quantum-languages. My question is similar to this, however, for me, "good" means:
What it does could be described in 1-2 paragraphs, and should be easy to…
klenium
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How to know if your gate set is "complete"
In Daniel Greenbaum's paper, "Introduction to Gate Set Tomography", in page 20, he claims the gate sets $G = \{\{\}, X_{\pi/2}, Y_{\pi/2}\}$ and $G' = \{ \{\}, X_{\pi/2}, Y_{\pi/2}, X_{\pi}\}$ with $F_k \in G$, $F_k |\rho\rangle\rangle$ are able to…
Cuhrazatee
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Continued fractions with Shor's algorithm: which convergent?
Suppose I am using Shor's order finding algorithm to calculate the order $r$ of $x\leq N$ with respect to $N$. After some run of the QPE subroutine, I obtain a good, $L$-bit approximation to $s/r$ for some $s\leq r$. According to, say, Nielsen and…
Jacob
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In Cirq, how do you display circuit diagrams that are "prettier" than the ones displayed by default?
This is a duplicate of a question that was asked on the Cirq issues page. I'm duplicating this question to increase it's visibility.
Victory Omole
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Quantum implementation of arcsin
I am looking to implement a quantum version of the arcsinus function. Such a problem is motivated by the HHL algorithm where $x\mapsto 1/x$ and $\arcsin$ can be used to get $1/x$ from the computational basis state into the amplitude.
My questions…
SRichoux
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Classical algorithm with complexity similar to Shor's discovered: Are there more efficient quantum algorithms than Shor's?
In the article Fast Factoring Integers by SVP Algorithms the author claims that he discovered classical algorithm for factoring integers in polynomial time. The Quantum Report mentioned here that it has similar performance to Shor algorithm which is…
Martin Vesely
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How does the NOT gate generalize beyond binary?
If we are working with qudits instead of qubits, how do the NOT and CNOT gates work? If the control state for a qubit system is $|1\rangle$, what is it for a $d$-ary qudit system, and why?
For instance, in a qutrit system with three basis states…
Sam
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Can the analysis or design of quantum algorithms benefit from parameterised algorithmics?
In the last decades, the field of parameterised algorithms, with fixed parameter tractibility (FPT) as its main tool has been provided new methods to analyse old algorithms and design techniques for new algorithms.
The basic idea of parameterised…
Discrete lizard
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Why does QAOA achieve quantum supremacy in an algorithmic sense?
In the paper Quantum Supremacy through the Quantum Approximate Optimization Algorithm the authors claim (last sentence of page 15):
"If [...] the QAOA outperforms all known classical algorithms then it will achieve Quantum Supremacy in an…
Nepomuk Hirsch
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What is the computational complexity of quantum annealing?
Quantum annealing can be thought of as a black box solver that can find approximate solutions to hard optimization problems. For example, D-Wave quantum annealers can approximately solve quadratic unconstrained binary optimization (QUBO) problems,…
Dr. Prasanna Date
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Quantum Amplitude Estimation vs Quantum Phase Estimation
Quick question concerning the probability of success after a phase estimation algorithm vs an amplitude estimation algorithm.
Given the calculation on the wikipedia page, the probability of measuring the desired output in a phase estimation…
sheesymcdeezy
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If quantum computing always return random measurement (or uncertain measurement), why do we still need it?
I am very new to quantum computing and currently studying quantum computing on my own through various resources (Youtube Qiskit, Qiskit website, book).
As my mindset is still "locked" with classical computation, where input and output are very…
KamWoh Ng
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Can we use quantum parallelism to calculate many functions at once?
It is well-known that by utilizing quantum parallelism we can calculate a function $f(x)$ for many different values of $x$ simultaneously. However, some clever manipulations is needed to extract the information of each value, i.e. with Deutsch's…
donnydm
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