Questions tagged [qiskit]
Quantum Software Development Kit for writing quantum computing experiments, programs, and applications. If appropriate, also use the [programming] tag.
334
questions
1
vote
0answers
21 views
Qiskit not installing properly on pyCharm CE
I have installed qiskit through my terminal using pip3 install qiskit. But when I try to import all from it in my coding software, it returns a M...
0
votes
0answers
11 views
Error parameters from Qiskit backends
In order to build a custom noise model in Qiskit Aer, I requested the error parameters from different backends and got 3 (9) parameters for each single-qubit (two-qubit) gate as output. However, I ...
0
votes
2answers
31 views
How to perform operations like sin over Qiskit parameters
I want to create a parameter dependent gate in qiskit and I need to compute some complex operations as sympy.atan2 or sympy.sin ...
1
vote
1answer
24 views
$\lambda$ parameter for U3 gate in qiskit Bloch sphere visualisation
It is easy to see how $\theta$ (rotation from the positive z-axis) and $\varphi$ (rotation from the positive z-axis) affect the initial state of the qubit when looking at the Bloch sphere but I have ...
1
vote
1answer
28 views
Qiskit - Z expectation value from counts?
For a given state $|\psi\rangle$, how would I work out $\langle\psi|Z|\psi\rangle$ ?
If I run a quantum circuit and get the counts dictionary on qiskit, I get observables in the Z basis.
For n=1 ...
2
votes
1answer
38 views
Gate corresponding to $-I$
I am implementing a quantum circuit in Qiskit. I create the equal superposition state
$$
-|00\rangle + |01\rangle + |10\rangle +|11\rangle
$$
but I want to obtain the quantum state
$$
|00\rangle - |...
4
votes
3answers
170 views
Quantum circuit to implement matrix exponential
I want to build a circuit which will implement $e^{iAt}$, where $ A=
\begin{pmatrix}
1.5 & 0.5\\
0.5 & 1.5\\
\end{pmatrix}
$ and $t= \pi/2 $.
We see that $A$ can be written as, $A=1.5I+0.5X$. ...
1
vote
0answers
32 views
How can I run programs in test folder Github Qiskit
I am new to GitHub/Python - please tell me how can I run programs in https://github.com/Qiskit/qiskit-aqua/tree/master/test and its sub directories in Jupyter. I am connected to IBM Q Expereince. I am ...
3
votes
1answer
83 views
How does the teleportation circuit work after the initial entanglement?
I'm trying to understand why we do what we do when we teleport a state from Alice's first qubit to Bob's qubit. I understand the initial entanglement, but could use help walking through the program.
...
1
vote
1answer
45 views
Understanding the working of oracle in Deutsch - Josza Algorithm
Reading through the official Qiskit textbook, I fell onto the problem of Deutsch - Josza Algorithm, which seemed little mystical to me at first but as I tried out the example of its working, I was ...
1
vote
2answers
78 views
What is the risk factor on IBM's portfolio optimization notebook?
In the notebook "portfolio optimization" on IBM's platform the goal is to calculate the optimal stock selection using a classical and a quantum algorithm (VQE). A random portfolio is generated and ...
1
vote
3answers
88 views
Error while running Quantum Teleportation Algorithm on real device using qiskit on IBM-Q
I am trying to implement Quantum Teleportation Algorithm on an actual device, I am using IBM-Q Jupyter notebook for the same purpose.
The code is as follows:
...
2
votes
1answer
34 views
How to calculate state fidelity in Qiskit?
I have a circuit with different structures, now I'm trying to calculate the fidelity between those with the original one. How do I calculate the fidelity? I want also to initialize the state vector by ...
1
vote
1answer
59 views
Eigenvalue and eigenvector in Qiskit
I want to calculate eigenvectors and eigenvalues for real symmetric matrix or Hermitian matrix. Can I use this: https://qiskit.org/documentation/api/qiskit.aqua.components.eigs.Eigenvalues.html
2
votes
0answers
54 views
How does Quantum Teleportation works? [duplicate]
I've started learning Quantum Computing from the Qiskit Textbook and was able to easily understand or work out everything until it came to the working of Quantum Teleportation
I can understand the ...
2
votes
1answer
111 views
Different QFT results when using Simulator or Quantum Machine
I'm performing QFT using the following code:
...
1
vote
1answer
30 views
qiskit: IQFT acting on subsystem of reversed-ordered qubits state
I have a state psi as an ndarray of shape (2 ** 3,) s.t.
psi[0]= amplitude of 000
...
1
vote
1answer
31 views
In Qiskit, where is the floating point operation performed?
I am using Qiskit - the simple circuits I am writing can either run on the hardware backend (using least_busy) or the QASM simulator backend.
If I have statements like the following - (...
2
votes
2answers
78 views
Mitigating the noise in a quantum circuit
I'm using Qiskit and I have a Quantum Circuit (say, circuit) that gives reasonable results when using the simulator, namely
...
2
votes
1answer
117 views
How many Qubits does the qiskit implementation of Shor's Algorithm need to factor N=15?
I know there is a documentation for qiskit.aqua.algorithms.Shor that explains that they used this reference for implementing the actual circuit. It says that the number of qubit needed is 2n+3. So to ...
2
votes
2answers
63 views
How to measure in the bell basis?
The question is quite straightforward, I have some two qubit state and I want to measure it in the Bell basis. This question answers me partly, but I still have some doubts because, I thought that ...
2
votes
1answer
46 views
How to calculate the Von Neuman entropy on qiskit with the module quantum_info?
I am trying to wrap my head around he quantum_info module on qiskit, since most of the functions on qiskit.tools are going to be ...
2
votes
1answer
47 views
Finding optimal values of depth and max_trials parameters in vqe algorithm
I am running vqe algorithm in qasm_simulator and cannot get the optimal solution.
Are there any methods for finding the optimal value of depth for variational form and max_iter for optimizer ...
0
votes
2answers
33 views
What do the numbers of the operation object in QuantumCircuit.data outputs?
When you have a quantum circuit and use QuantumCircuit.data you get a list with objects of this type (this is the one for a X gate acting on qubit 0 y a 2 qubits Quantum Circuit):
(qiskit.extensions....
0
votes
1answer
30 views
Why doesn't qiskit appear in “help(”modules“)” even though it is installed in python environment?
I have updated qiskit to the newest version using pip install qiskit --upgrade and all was done successfully, and when I write ...
1
vote
1answer
17 views
Qiskit visualizations module not installed but qiskit package installed. Why?
I am trying to set up my qiskit environment but I seem to have run in trouble that I have no idea how to solve. I have installed the qiskit packages as can be seen by running ...
3
votes
1answer
35 views
Make a doubly controlled gates from existing operations
I'm trying to implement an modular adder mentioned here with qiskit. I have already built the $\Phi ADD$ gate. But in order to build a modular adder like in figure 5 in the paper, I need to build a ...
-2
votes
0answers
57 views
How to solve error AttributeError: 'numpy.ndarray' object has no attribute 'keys' in Qiskit? [closed]
I obtained error shown below. Does anybody know what does it mean and how to solve it?
...
2
votes
1answer
38 views
Modifying Qiskit Hamiltonian
I'm fairly new to the Qiskit API. I was wondering if I could get some assistance with trying to implement our technique of projecting out a new Hamiltonian from the ground-state Hamiltonian. The ...
1
vote
1answer
55 views
Qiskit statevector_simulator returns different results
I'm running VQE algorithm from qiskit aqua on statevector_simulator and each time I run it I get different results which are sometimes correct and sometimes not. I'...
0
votes
0answers
29 views
State fidelity in Qiskit
Can someone provide me an example for finding state fidelity of two circuits?
For example, if I have a Toffoli gate with two different approaches of decomposition then how do I calculate fidelity ...
1
vote
1answer
32 views
VQE with error dim. mismatch using qiskit.aqua.vqe
when i try to call the VQE from qiskit I get an error of dimmismatch. The input matrix is of a 16x16 shape and I could not find out what where I introduce the error. In the picture The input matrix ...
1
vote
1answer
39 views
How to deal with the relative phase from the evaluation of the not interacting qubit?
Every qubit is a realization of some two-level quantum system with $\left| 0 \right\rangle$ and $\left| 1 \right\rangle$ states. These states have their energies $E_0$ and $E_1$ respectively. By ...
0
votes
1answer
34 views
Is there a limited number of features for QSVM in Qiskit-Aqua?
Why all tutorials that use QSVM from qiskit Aqua library have the number of features equal to 2?
Thank you!
1
vote
1answer
46 views
Are $\mathrm{cRz}$ with angle $\pi$ and $\mathrm{cZ}$ equal on the IBM Quantum Experience?
I was trying to implement the 2-qubit Grover algorithm without the auxiliary bit. Before finding the gate symbol for the controlled $\mathrm{Z}$, I worked with the controlled $\mathrm{Rz}$. The gate ...
0
votes
0answers
38 views
How can I find the fidelity of preparation?
I want to know the fidelity (or error rate) of the preparation ($|0\rangle$)
How can I have it?
1
vote
1answer
44 views
How do I know in which state the qubit is in each step of the circuit for the simulator in qiskit?
I would like to know how to know in which state a qubit is (I am talking about single-qubit errors), because in order to apply a non unitary gate in the simulator I have to renormalize the state or ...
2
votes
2answers
71 views
How to read the elements of a circuit in qiskit?
I would like to know if there is a way to read the elements of a circuit. What I mean is if I have a QuantumCircuit object, can I obtain the gates that are applied ...
2
votes
1answer
130 views
How to use external .csv data file in quantum support vector machine qiskit python code?
I am new to python programming and Qiskit. I would like to ask can we use sklearn for adding external .csv data file before Qiskit libraries, or without sklearn, we can do or is there any other Qiskit ...
1
vote
1answer
41 views
IBMQ: `from qiskit import QISKitError` gives 'cannot import name QISKitError'
When I run:
from qiskit import QISKitError
I get the error:
ImportError: cannot import name 'QISKitError'
I need ...
1
vote
0answers
31 views
Loading old results for Data reprocessing
I want to process some old data again. How do I load old data retrieved from IBM-Q into a new program? I've downloaded the relevant .json file, but I don't know how to use it like I would have a new ...
1
vote
1answer
32 views
Toffoli gates with Hadamard coins (QISKIT)
I am creating the following circuit with Qiskit (2Toffoli gates controlled with coins)
And to set the coins for one iteration of the circuit i do the following :
...
2
votes
1answer
172 views
How to make circuit for randomly selected gate?
I am trying to make a circuit for the randomly selected gates from a gate_list but I don't know how to put these selected gates in front of ...
1
vote
0answers
40 views
Implementing QFT
I would like to know if there is a way to:
Implement Quantum 'Functions' e.g the QFT of QFT* containing several single-qubit operations?
Implement such operations on an arbitrary number of qubits and ...
2
votes
0answers
24 views
How to simulate spin-1 systems with qiskit or on the IBMQ platform?
I am wondering how to simulate spin-1 systems with qiskit or on the IBMQ
platform? I want to initialize a qudit (a spin-1 system), and then define the usual operations (such as Sx, Sy, and Sz) on the ...
3
votes
1answer
656 views
Superdense coding circuit returns wrong result
I'm new to quantum computing, but everything I've read about superdense coding claims that, in the circuit below, Bob should receive a $[01\rangle$ from Alice.
Unfortunately, that's not what I get ...
1
vote
1answer
48 views
Achieve a control gate with 2 hadamard coins
I want to implement two Toffoli gates with 4 qubits:
3 serving as control qubits (the 2 hadamard coins and one other qubit) and
the last one as target qubit and 3 qubits (2 coins 1 target qubits) as ...
1
vote
0answers
96 views
Decomposition of an arbitrary gate using given matrix in Qiskit
If I have an arbitrary non-unitary matrix of say
$$
U = \begin{pmatrix}
1.5 & 0 & 0 & 0 \\
0 & 0 & 0 & 1.6 \\
0 & 0 & 1 & 0 \\
0 & 1 & 0 & 0 \\
\end{...
2
votes
1answer
63 views
What is the source of this TranspilerError when running qasm file?
I want to run this qasm file using IBM device.
However, there's always an error:
...
3
votes
1answer
111 views
Generate the state $\frac{-|0\rangle + |1\rangle}{\sqrt{2}}$ with qiskit: problem with Pauli-Z behavior
I want to construct the following state of a qubit using a quantum circuit: $\frac{-|0\rangle + |1\rangle}{\sqrt{2}}$
When I use the following qiskit code in Python:
...
