Questions tagged [algorithms]
For questions about an algorithm as it relates to physics. DO NOT ask how to implement an algorithm, questions like that belong on Stack Overflow or Computational Science. DO NOT ask about the efficiency of an algorithm, or other such questions, questions like that belong on Computational Science.
142
questions
1
vote
1
answer
336
views
Number of qubits required in Shor's algorithm
People say that the number of qubits required in Shor's algorithm for factorizing $N$ should be
$2\log N$ for control register and $\log N$ for target register.
What is the reason why these numbers of ...
- 185
1
vote
0
answers
140
views
Is there a comparison table for quantum algorithms like VQE, QPE, QAOA, and so on?
I have one question: Recently, I studied about several algorithms like VQE, QPE, QAOA and so on. I would like to make some comparison tables about those algorithms, their strengths and weaknesses. If ...
11
votes
1
answer
1k
views
Why use Crank-Nicolson over Matrix Exponential when solving Schrödinger's equation?
For Schrödinger's equation,
$$\psi(x,t+\Delta t)=e^{-i H\Delta t}\psi(x,t)\approx\frac{1-\frac{1}{2}i H\Delta t}{1+\frac{1}{2}i H\Delta t}\psi(x,t).$$
The right-most expression is the Crank-Nicolson ...
- 779
1
vote
0
answers
122
views
Final Hamiltonian for Adiabatic Grover
X-Posted on Quantum-Computing Stack Exchange
In quantum computation, there is a famous algorithm to search a marked item in an unstructured database called Grover's algorithm. It achieves a quadratic ...
2
votes
0
answers
41
views
Why is the boundary of friends-of-friends (FOF) halo corresponding to iso-density contour?
The friends-of-friends algorithm (hereafter FOF) is commonly used to find halos in cosmological simulations. (For more information, please refer to here and here)
I found that some literature argues ...
- 529
5
votes
2
answers
361
views
Is the universe's Kolmogorov complexity growing over time?
The Kolmogorov complexity of a deterministic universe is constant.
The Kolmogorov complexity of a nondeterministic universe grows over time. It grows whenever something happens that is not ...
- 129
1
vote
1
answer
746
views
Bell State Measurement Algorithm
I'm relatively new to quantum computation and am taking a course in it. I was wondering if it is possible to code an algorithm which would be able to take an input of a 2 qubit state and perform a ...
- 21
1
vote
0
answers
28
views
Modeling curved light in media with "complex" indices of refraction
I've written an algorithm to solve the Time Difference of Arrival (TDoA) localization problem, using Bancroft's method (see). Given the coordinates of $n$ nodes in ...
- 799
0
votes
1
answer
443
views
How to calculate acceleration due to gravity in a 3D $N$-Body system?
How do you calculate acceleration due to gravity for objects in 3D space?
My current understanding for the force due to gravity on object $i$ from object $j$ is
$$\mathbf{F}_g=(\mathbf{r}_j-\mathbf{r}...
- 157
0
votes
1
answer
100
views
Novikov self-consistency and computability
The Wikipedia article on the Novikov self-consistency principle has a section on time loop logic, where it discusses using time travel to solve any NP problem by finding an algorithm where the only ...
- 103
5
votes
0
answers
460
views
Is the only difference between tDMRG and TEBD the way the central sites are shifted?
I have been reading up on time evolution methods using matrix product states. Reading from Schollwoeck's notes on the density matrix renormalization group, (https://arxiv.org/abs/1008.3477), I looked ...
- 141
8
votes
1
answer
173
views
Github for Physicists
I am wondering if there is a platform to which researchers share or publish the code they used in their research. I noticed that many researchers explain their algorithm and math and present the ...
1
vote
0
answers
110
views
Numerical renormalization of 2D Ising lattice
I'm trying to make some toy computations on the $2D$ Ising model on a square lattice. I want to apply a renormalization transformation, and try to estimate observables on the renormalized lattice ...
- 4,736
2
votes
1
answer
426
views
Is estimation partition functions without resorting to markov chain monte carlo still an open question?
I was told estimation of partition functions without resorting to MCMC was still an open question in physics about a year and a half ago. An example is that say you have some physical model that ...
- 73
2
votes
1
answer
56
views
Can I have detailed balance without reverse updates?
I am implementing a Markov Chain Monte Carlo algorithm and want to obtain a stationary distribution. In order to do this I want to have detailed balance, as this is a sufficient, although not ...
- 1,772