Questions tagged [qiskit]
Quantum Software Development Kit for writing quantum computing experiments, programs, and applications. If appropriate, also use the [programming] tag.
1
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1answer
29 views
Import from qiskit-aqua error
I try to use Quantum SVM kernel algorithm: multiclass classifier extension. This is my code section with imports
...
3
votes
2answers
70 views
Problems with qiskit-terra: missing members of instance QuantumCircuit
I have installed a Python 3.7.2, download anaconda and visual studio code. Install Qiskit SDK 0.5.3. But when I launch my first test program from https://github.com/Qiskit/qiskit-terra I received a ...
5
votes
3answers
97 views
How is the Grover-Algorithm applied to a database?
Question
I want to use the Grover-Algorithm to search an unsorted database for an element $x$. Now the question arises, how do I initialize index and value of the database with the qubits?
Example
...
2
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1answer
31 views
Qiskit predecessor and successor map of DAG circuits
I am trying to figure out how to use the functions "_make_pred_succ_maps". Here is a description of the function from Github:
...
3
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2answers
103 views
Finding the second smallest number. Is it achievable in QC?
I have a set of numbers in a superposition state (example: 3,8,1,5) in a quantum register (of 3 qubits).
So I try to find the $n^{\text{th}}$ smallest number (...
3
votes
0answers
33 views
What are reasonable noise/dephasing parameters for QuEST to emulate state-of-the-art quantum computers?
The QuEST code allows for simulation of quantum computers taking dephasing and depolarizing noise into account via one and two qubit dephasing and depolarization. What are realistic parameters for ...
4
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1answer
77 views
Quantum algorithm for linear system of equations (HHL) - Final Step: How can I find my vector of solution $|x\rangle$?
I'm working on solving a linear system with the quantum algorithm HHL. I don't understand how I can recover my vector $|x\rangle$ of real solution of the system starting from the states measured with ...
3
votes
1answer
67 views
For CNOT gate with control qubit set to 1, the measured state of the second qubit unexpectedly depends on the measurement
I have the following circuit in qiskit. It is a simple CNOT operation with the control qubit set to 1, by running the control qubit through an X-gate.
However, when I measure the 2nd qubit, I get the ...
2
votes
1answer
38 views
Building an N-qubit Controlled S Gate
I've been beating my head against this problem for three days now and I just can't seem to crack it. To construct an N-qubit controlled Unitary gate, I can do something like this (note I'm using ...
3
votes
1answer
58 views
“Wait” gate throws an error “NotImplementedError: ('No decomposition rules defined for ', 'wait')”
My Quantum circuit contains "Wait" Gate. When I try to execute it (qasm_simulator or unitary-simulator), it throws an error . ...
1
vote
1answer
45 views
Cannot load account with Qiskit
I just got started with Qiskit. When I tried to save my account with the API token from IBMQ website, I got the error: ...
1
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0answers
28 views
Qiskit gates in LaTeX representation: notation meaning [duplicate]
I started working in Qiskit, and here is an example of how gates of a circuit are represented graphically in LaTeX format:
Obviously, $R_y(\theta)$, is a y rotation by a certain angle. But all the ...
3
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1answer
46 views
Consistent QISkit error: “All devices are currently unavailable”
I am attempting to run the following on a remote backend through QISkit:
...
3
votes
1answer
65 views
Is it possible to create a superposition in IBMQ QISkit which has probability amplitudes $|a|\neq |b|$?
For example, we can create a single qubit state with a polar angle of $\pi/2$ with the Hadamard gate. But, can we create a state such as this,
$$\Psi = \cos(\pi/8)|0\rangle + \sin(\pi/8)|1\rangle$$
...
1
vote
1answer
90 views
QISKit warrning on marshmallow
I have updated qiskit module but unfortunately, it doesn't work it says
...
4
votes
1answer
62 views
Qiskit - How do we measure the same single qubit system multiple times while also getting the counts/results after each measurement?
I am able to apply multiple measurements (2) to the same qubit system. However, I would like to get the counts right after each measurement is executed. I realize that the counts should be the same ...
3
votes
1answer
34 views
LaTeX error when drawing circuits with Qiskit
I am currently running the following document from this Qiskit documentation.
This notebook is running in Jupyter, and I started Jupyter from the Mac terminal within a Conda environment. Normally, ...
2
votes
1answer
36 views
Qiskit: 'per shot' result
Is there a way to access the results of measurements 'per shot' performed on a backend such as one of the real IBM machines?
I know it can generate a histogram from the cumulative data, but I was ...
4
votes
1answer
204 views
ImportError: cannot import name 'QuantumProgram' from 'qiskit'
I get below error when I run a code on spyder environment:
File C:/MYPYTHON Programs/My Quantum Programs/Shor algo.py, line 4, in from ...
4
votes
1answer
99 views
Deprecation warnings in Qiskit (circuit drawing)
I am just starting to get around Qiskit, I'm going at baby steps, so I tried to run the code below and I noticed three things:
I tried using ...
3
votes
1answer
117 views
Path to learn Qiskit as a tool for the future
I am an undergraduate in Engineering physics, yet to take classes on Quantum mechanics, but none (if I'm not mistaken) on quantum information and quantum algorithms, and I am curious about the subject ...
3
votes
2answers
154 views
Why won't Qiskit ccx gate accept registers?
In Qiskit, they have the concept of a Toffoli gate (ccx). However, the following code throws an error:
...
8
votes
1answer
135 views
Submitting jobs to IBM devices without Python
Qiskit can be used to submit jobs to IBM devices using Python (or Swift and JavaScript). But what if I want to use a different language?
For example, suppose I have a specific circuit I want to run. ...
2
votes
1answer
97 views
Plotting data in QISKit using plot_histogram
I'm trying to plot a set of data using plot_histogram, but the rendered image looks like this (the larger values are outside the image):
How can I set the y-...
1
vote
1answer
56 views
TypeError: unorderable types: QuantumRegister() >= int()
I've been using qiskit for about a year now, and as of late, I've had issues finding an available backend to run my circuit on. Looking into the matter, I reinstalled qiskit to find that most ...
5
votes
1answer
126 views
Status of software packages for quantum compiling
By "quantum compiling", what I mean is classical algorithms to solve the following problem: given a $SU(D)$ matrix $U$ (the goal) and a set of $SU(D)$ unitary matrices $V_1 \cdots V_N$ (the gates), ...
3
votes
1answer
78 views
Can I remove gates from a QuantumCircuit?
Suppose I want to implement run several circuits one after another, but they are constructed in a similar fashion. I could reinstantiate a QuantumCircuit for each ...
4
votes
1answer
84 views
How can noise on a device be simulated using measured noise parameters?
The real devices used as backends for Qiskit have calibration data that quantifies errors ($T_1$ and $T_2$, gate fidelities, etc). This can be accessed by, for example
...
2
votes
1answer
52 views
Result of a job for a list of circuits on QISKit
Suppose Circuits= [circuit1, circuit2, ..., circuitn] is a list of defined circuits. Then, ...
2
votes
0answers
40 views
Introspecting quantum circuit execution on Qiskit Aer simulators
Is there any way to get information from intermediate points in the execution of a quantum circuit. This is not possible on real quantum hardware but would be very useful on the Aer simulators for ...
1
vote
1answer
58 views
Entanglement in VQE ansatz in Qiskit
The Qiskit documentation on VQE describes two of the ansatz as "rotations with entanglements". The rotation gates are more or less clear, but the documentation doesn't mention what gate is used for ...
3
votes
1answer
49 views
Programming quantum half adder
While computing the carry bit [C=0 XOR (AB)] I am unable to compute that AB in Qiskit. I don't whether Toffoli gate is available in Qiskit. So does anyone know how to perform AB, which is basically ...
1
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0answers
57 views
Qiskit - Authorization Required error
When I use Qiskit to do quantum computing, I suffer from a big problem.
When running the code,it turns out to be:
...
3
votes
1answer
60 views
Qiskit - expand and/or merge registers
Suppose one of my functions create some ancillary qubits and reset them.
Then, another function wants to create a larger number of ancillary qubits. So, I'd like to reuse the first set of qubits and ...
1
vote
1answer
324 views
ModuleNotFoundError: No module named qiskit.providers
The following message I got by running the qft.py code
Traceback (most recent call last):
File "qft.py", line 18, in
...
1
vote
1answer
136 views
Module BasicAer not found
After installing qiskit-terra via git (pip install qiskit), all python programs involving the line ...
5
votes
4answers
211 views
How do I build a gate from a matrix on Qiskit?
I'm creating a gate for a project and need to test if it has the same results as the original circuit in a simulator, how do I build this gate on Qiskit? It's a 3 qubit gate, 8x8 matrix:
$$
\frac{1}{...
2
votes
1answer
59 views
Print circuit compiled on hardware?
I would like to see the compiled circuit as executed on a hardware.
Nominally, this sequence of commands should return the QASM circuit in the variable ran_qc, but ...
3
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2answers
126 views
How to fix? 'E1101:Instance of 'QuantumCircuit' has no 'h' member' and 'E1101:Instance of 'QuantumCircuit' has no 'cx' member'
I'm using this simple code to test my Qiskit and learn how to use it but it keeps giving this problems, how do I fix it (Using VS Code and Anaconda Python 3.7)
...
2
votes
1answer
94 views
qiskit - Is there any way to discard the results of a measurement?
I have a circuit composed by n qubits, plus a single one which is an ancilla. I'm making multiple measurements on the ancilla at different stages of the circuit, ...
2
votes
1answer
226 views
Is it possible to expand/merge different circuits?
Suppose I have created a circuit composed of some registers with the usual
qc = QuantumCircuit(qr, cr)
where qr and ...
3
votes
1answer
97 views
How to set up Qconfig.py and where is the file?
How to set up Qconfig.py and where is the file? I mean under which folder? Like /anaconda/lib/python3.6/site-packages/qiskit/.
3
votes
2answers
114 views
Implementing gate with two parameters using Qiskit in Python
I am trying to implement the HHL algorithm (for solving $Ax=b$). I am assuming $A$ to be unitary and Hermitian so that I can find the Hamiltonian simulation for it easily.
For any $A$ to be Hermitian ...
8
votes
2answers
190 views
Qubits specification on IBMQ devices
As it is shown here, CNOT gates between different qubits have different error rates. I have the following questions:
1) While defining a circuit on QISkit, does ...
1
vote
2answers
112 views
How can the state $\lvert0\rangle+M^{-1/2}\sum_{j=1}^M\lvert j\rangle$ be generated?
I was wondering if anybody to help me to generate the following state.
It would be preferable if you use only Hadamard, CNOT and T-gates, on $\lceil\log_2(M+1)\rceil$ qubits:
$$|\psi\rangle = \frac{1}{...
2
votes
2answers
118 views
How to run algorithms on IBMQ via Qiskit-Aqua?
I am trying to run an optimization problem on IBMQ. Running the same code on QASM simulator works fine. However, changing only the backend name to IBMQX takes long time. I am aware of the queues ...
2
votes
0answers
316 views
Qiskit SDK problem
So I am getting this error when I fire the command on Ipython or Jupyter Notebook
...
2
votes
0answers
171 views
Qiskit Python program cannot connect to QE API
I am just getting started with Qiskit and IBM Quantum Experience, so please forgive my newby question.
I have a IBM Quantum Experience account and I generated an API token.
I used the generated ...
5
votes
1answer
120 views
Entanglement state preparation by using amplitude values
I have an algorithm that uses QRAM, after accessing the given QRAM that store M d-dimensional classical vectors, the state of the index register and the data register become entangled. But for now I ...
3
votes
1answer
89 views
How can I resolve the error QISkit Error: The same provider has already been registered!
I am writing a small algorithm to multiply two numbers using IBM's QISkit. The code is below:
times_shell.py
...
