Questions tagged [qutip]

For questions about code which makes some use of QuTiP (Quantum Toolbox in Python). It is an open-source software library for simulating the dynamics of closed and open quantum systems. Please don't use the programming tag unless you absolutely think it is related to your question. Basically, questions which involve calculating physical quantities, by doing numerical computations on a computer are suited for this tag.

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1answer
37 views

Defining dimension of an operator in qutip

My main question: Can someone please explain to me how the list of array is used to define the dimension in qutip ? context: If I have my density operator ...
-1
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1answer
41 views

Find orthogonal state for random 7 qubit state

I have a system that generates a random 7 qubit state and I need a method to always find the orthogonal state. I'm currently using python and qutip for this, representing this 7 qubit state by a 128-...
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0answers
25 views

How to simulate master equation with a term of “cascaded formalism” with QuTiP?

I would like to simulate this master equation with QuTiP. The term in the second line is the so called "cascaded formalism" used for eliminates any feedback from system to the input nodes. But the ...
0
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1answer
34 views

Using entropy_mutual function in QuTiP

I am trying to calculate mutual entropies using QuTiP, but I am being unsuccessful so far. More specifically, I consider a 2^n x 2^n matrix representing the density operator of a n-qubit bipartite ...
0
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2answers
52 views

Is there quantum error correction code package for python

I'm working on the development of a new quantum error correction protocol that tries to maximize the coherence of the qubit. Is there a package for python, similar to qutip, that could help me in this ...
2
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0answers
38 views

Numerical methods for finding an eigen basis of a degenerate Liouvillian

I'm trying to find the steady-state of a master equation, $$\dot{\rho}(t) = \mathcal{L}\rho(t),\tag{1}\label{1}$$ In the form where we vectorise the density matrix and matrixify (??) the Liouvillian ...
1
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0answers
14 views

Modelling reservoir in Qutip

Is there any way to model reservoir in QuTIP? I was trying to simulate a two sided cavity coupled with a reservoir using QuTIP and I can't find out how the reservoir terms in Hamiltonian are added to ...
2
votes
1answer
115 views

Strange Behaviour of MeSolve, McSolve

I'm using Qutip to plot some basic two level dynamics using hamiltonians with a temporal envelope defined as the sum of two error functions, designed to make it more representative of experimental ...
1
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1answer
351 views

Can't plot points on the Bloch sphere (QuTip)

I have the really odd problem when it comes to plotting Bloch spheres using QuTip. Plotting state vectors works perfectly fine e.g. ...
2
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0answers
62 views

How to define initial state $\rvert \Psi(0) \rangle \equiv \rvert 1, -1 \rangle \otimes \rvert 0 \rangle_{\text{cav}} $ of a system in QuTiP?

Say, we have a $\require{mhchem}\ce{^87Rb}$ atom having an electric dipole transition on the $D_{1}$ line and we have two hyperfine ground states, one on $F = 1$ and one on $F = 2$ level. So, we take ...
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0answers
39 views

Is the analytical solution right?

This question requires the knowledge of GRAPE. More info can be found here and in this short presentation. In the following jupyter notebook is the analytical solution as in this image right? Because ...
0
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0answers
35 views

Different values of similar functions

This question requires the knowledge of GRAPE. More info can be found here and in this short presentation. In the following jupyter notebook the result of this line _overlap(result.U_f, ...
1
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0answers
42 views

What is the need of convolution here?

This jupyter notebook implements GRAPE for the synthesisizing a CNOT gate. More info can be found here and in this short presentation. In the following jupyter notebook at In[8] 1 the starting ...
2
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0answers
76 views

Modifying GRAPE for open quantum systems

This question requires the knowledge of GRAPE. More info can be found here and in this short presentation. I have tried to modify the grape_unitary() function in grape.py also to accommodate open ...
3
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0answers
54 views

How to add states on the Bloch sphere from a master equation?

Can you please help me to find an answer to this question: I am using qutip for the study of quantum systems. suppose I have calculated the solution of the master equation using the ...
4
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1answer
492 views

Plotting Bloch sphere in QuTiP

Is there anyone who reproduced the Bloch sphere given in the paper QuTiP: An open-source Python framework for the dynamics of open quantum systems by J. R. Johansson, P. D. Nation, Franco Nori? I am ...
2
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1answer
120 views

How to prepare a statistical mixture of $|0,0\rangle $ and $ |1,1\rangle $ in QuTiP?

A QuTiP novice here. It's easy to prepare a pure state in QuTiP. For example, to prepare $\frac{1}{\sqrt{2}}(|0,0\rangle + |1,1\rangle)$: ...
5
votes
1answer
377 views

Drawing tangent vectors to the Bloch sphere with qutip

I need to plot drawings of qubit dynamics on the Bloch sphere. I know QuTip allows to do such drawings but I specifically need to represent evolution velocities on the Bloch sphere so I need to draw ...
6
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4answers
855 views

Measuring qubits in QuTiP

How can you measure qubits in QuTiP? As far as I have seen you can define a Hamiltonian and let it evolve in time. It is also possible to define a quantum circuit, however, measuring and running it ...
4
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0answers
250 views

Computing Majorana “Stars”

I'm trying to implement Majorana's "stellar representation" of a spin-$j$ system as $2j$ points on the $2$-sphere in python. Consulting papers including Extremal quantum states and their Majorana ...