All Questions
Tagged with programming hamiltonian-simulation
36 questions
0
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45
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Cosine of an operator (a+a.dag()).cosm() in Qutip does not work as it should
As mentioned in the title, the .cosm() method in QuTip fails to give the correct evolution under the Hamiltonian. I am trying to define the Hamiltonian of a non-linear LCJ circuit as follows:
...
- 11
0
votes
1
answer
93
views
Getting a Hermitian operator from a Quantum circuit, and taking its expectation value
I have a circuit $C$, which acting on a state $|\psi \rangle$ is equivalent to a Unitary $U$ acting on the state: $$C(|\psi \rangle) = U|\psi \rangle$$ Now, this circuit is just a Hamiltonian ...
2
votes
2
answers
152
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Hamiltonian Simulation: What's the meaning of t in $\exp(iAt)$?
My main goal is to find eigenvalues of some hamiltonian matrix $A$. When implementing Quantum Phase Estimation, I need to provide my circuit with informations about $A$. From what I have seen so far, ...
- 23
0
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39
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Particle number expectation value in QuTip
I am learning now to use QuTiP by going through their documentation site. I am trying to understand what does the argument - particle number expectation value in thermal density matrix do? How does it ...
- 33
1
vote
1
answer
62
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Qiskit: Evolve TrotterQRTE from Operator
I am trying to implement the method in the following paper: Exponential Quantum Speedup in Simulating Coupled Classical Oscillators using Qiskit.
All is good until I call evolve on ...
- 11
0
votes
1
answer
324
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Qiskit - Approximation of Hamiltonian energy via QPE
I'm trying to study QPE with the motivation of obtaining eigenvalues of Hamiltonian, i.e. energies of a system. My problem is, that while np.linalg.eig and VQE are agreeing on the lowest energy, ...
- 264
0
votes
1
answer
291
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How does the Active Space Transform work theoretically?
I have a question about the ActiveSpaceTransformer which is used in vqe calculations for a molecule of LiH in Qiskit. In the documentation the inactive Fock operator is defined.I don't understand why ...
3
votes
1
answer
397
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How to convert Pennylane decompose_hamiltonian to Cirq PauliString?
I have a matrix that I would like to decompose into a Pauli String. Pennylane's
qml.utils.decompose_hamiltonian does this and returns a list of coefficients and a list of operations representing the ...
- 31
5
votes
1
answer
3k
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Qiskit: PauliTrotterEvolution for Hamiltonian simulation
Context:
I have H (in qiskit.opflow notation).
I want a circuit which does exp(-itH)
Solution attempt:
I think qiskit.opflow.evolutions.PauliTrotterEvolution should do the trick.
Also, I found this ...
- 301
2
votes
1
answer
61
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Applying QPE on a large matrix on amazon-braket
I'm running a QPE algorithm on the amazon-braket but it can only apply on a 22 or 44 matrix, when I want to expand it into a 5*5 or more, it will come an error. As I know, there is no theoretical ...
- 21
1
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0
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49
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How can extract reduced dynamics of a bipartite system from unitary evolution in quite
Let us assume that I have a bipartite system $A\otimes B$ and an initial product state undergoing some evolution $H^{AB} = H^A+H^B+V^{AB}$, which is time independent. I want to simulate the reduced ...
- 153
3
votes
3
answers
627
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Are these two circuits equivalent in performing controlled time-evolution?
I want to perform the controlled time-evolution of some 2 or 3-qubit Hamiltonian. Say we have this example:
$$
H= Z_0\otimes Z_1 + Z_1\otimes Z_2
$$
The circuit performing the time-evolution ...
- 2,408
1
vote
0
answers
225
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Are inconsistent results between different VQE runs justified?
I made this post a while ago, where I learned I could use qiskit's VQE to calculate (or approximate) the Transverse Field Ising Hamiltonian and other similar Hamiltonians. After working with my code ...
4
votes
1
answer
2k
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Calculating the ground states of an Ising Hamiltonian on a real quantum computer
I have followed this tutorial and based on it, I've written the following function in qiskit, which can explicitly calculate the ground states of a transverse-field Ising Hamiltonian.
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4
votes
1
answer
335
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How to get eigenvectors of Hamiltonian in OpenFermion
In OpenFermion you can create a Hamiltonian in terms of creation and annihilation pretty easily:
...
- 75