Questions tagged [qiskit]

Quantum Software Development Kit for writing quantum computing experiments, programs, and applications. If appropriate, also use the [programming] tag.

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provider.backends( ) not responding in Qiskit?

please in need some help I want to get a list of the providers in Qiskit and i use the command providers.backends() yet it says provider not defined. any suggestions. thank you
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Qiskit: Initializing n qubits with binary values (0s and 1s)

Is there a way in Qiskit to initialize $n$ qubits with binary values (0s and 1s)? For example, how can I initialize two qubits in the state $|11\rangle$? Here is a code snippet: ...
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Suppress deprecation warnings from Qiskit

I am running a standard VQE from the example shown in here https://qiskit.org/textbook/ch-applications/vqe-molecules.html, however I keep getting this output constantly (as many times the vqe runs ...
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1answer
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Is it possible to implement c_if statement based on a measurement in a single specified classical bit in qiskit?

I'm trying to write a 1-bit teleportation error correction code and there is one part in it where I need to add a gate that's dependent on a measurement from earlier in the circuit. The measurement ...
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0answers
65 views

My Bloch sphere/ qsphere is appearing as an ellipse/oval

I tried to plot a Bloch vector. However, my Bloch sphere is appearing as an ellipse/oval instead of a circle. I am having the same issues with qsphere also. instead of ...
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1answer
77 views

Where can I find the Qiskit tutorial as a pdf?

A documentation of Qiskit language is provided on qiskit.org/documentation/. However, this is an on-line source and sometimes I would apprecite to have an off-line version at hand. My questions are: ...
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2answers
51 views

Error mitigation matrix as backend property: Are any “reliable” mitigation matrices publicly available?

Given that the error mitigation matrix (meas_fitter.filter) does not vary so much for a given backend and number of qubits, then what are the advantages and disadvantages in the determination of the ...
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Problem with installing Qiskit on Android with Termux emulator

Termux has some issues with cmake, therefore qiskit-aer-0.5.2 installation returns error 1. ...
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How to do state tomography when using sampling in Qiskit?

Could anyone please explain how do I do state tomography when using sampling (on real device or QASM) in Qiskit? I know there's a special method for this, but I could not find a working example. More ...
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1answer
22 views

Does Qiskit offer a stack of functions to generate and manipulate graph states?

I'm looking for a way to test graph state verification protocols on the IBM Q. Has anyone yet written code to generate a graph state on IBM Q and also generate its stabilizer generators given the ...
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1answer
58 views

qiskit.QuantumCircuit and qiskit.QuantumCircuit.draw()

The first time I create a two qubits, two bits circuit and draw it the output is: q0_0 q0_1 c0_0 c0_1 Each subsequent time I run my script (even after clearing ...
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Form and effect of the intrinsic Hamiltonian on the IBM machines

I want to understand the form of the intrinsic Hamiltonian of the IBM machines, such as ibmq_16_melbourne, and how this affects the data I get out when waiting ...
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How can I load a probability distribution using a quantum circuit in Qiskit?

Can someone suggest me a way to load a distribution (for example a discretized Gaussian distribution) into a quantum computer using a quantum circuit? I tried to implement the code using Qiskit.
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Is there a general order finding quantum algorithm for a given a and N?

I'm trying to construct a general circuit for Shor's algorithm in Qiskit. I understood the later parts of the circuit (inverse QFT and QPE), but can't really understand the order finding. For example, ...
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40 views

How to undo an operation in qiskit on jupyter notebook?

I am not able to undo an operation. For example, I want a single Hadamard gate on a single qubit but by mistake two Hadamard gate added. Now I want to remove one of them without interrupting kernel. ...
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54 views

Making custom gate in Qiskit?

I have been trying to make a gate in qiskit in terms of the basic gates, but I keep on getting an error when I apply it to a circuit. This is my gate: ...
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1answer
17 views

Queue disabled and HTTP 403 error

I have already visited this What does it mean to get 403 error when running a code on Qiskit? which did not help me fix my problem. I want to test the quantum circuit that I have designed using the ...
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What is the buffer time between gates of the ibmq_essex in nanoseconds?

This is a question that I asked on Qiskit ignis section of slack, with a very interesting answer by A Kapila, but I also need to get a short answer in nanoseconds. I want to evaluate decoherence in ...
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1answer
28 views

I cant transfer my API token to jupyter [closed]

Im watching the video How to install Qiskit programming on quantum computers EP 2, i'm at 7:29 and I cant Type in API token in the IBMQ.save_account("), the <...
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What is the executable opcode for Qiskit quantum hardware, as the quantum circuits or the transpiled/compiled QObj/ QASMQObj are assembly languages?

When we write a QASM code or build quantum circuit on Qiskit GUI, it converts it into QObj/QASMQObj (refering paper Qiskit Backend Specifications for OpenQASM and OpenPulse Experiments) or its ...
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2answers
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How to create the logical $|0_L\rangle$ state for the Steane's 7-qubit code?

I don't know how to prepare using Qiskit the following state in order to implement a Steane's 7-qubit code circuit (I omit the normalization factor): \begin{align*} |0_L\rangle =&|0000000\rangle+|...
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IBMQ / Qiskit slack links are broken [closed]

It appears the Slack links to IBMQ slack pages are broken (The link is no longer active). This is case for links on both Qiskit and IBMQ support pages. What is the best way to gain access to the Slack ...
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1answer
37 views

Is there a standard way to save pulse schedules akin to a qasm for a circuit?

If I create a QuantumCircuit, I can save all the information necessary to reconstruct the circuit using the qasm method. In addition, these qasm strings can be sent directly to the IBM quantum ...
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1answer
51 views

VQE jobs do not appear in queue

I am trying to calculate the ground state energy of some simple molecules using 'MolecularGroundStateEnergy' tools in qiskit. When I run the calculations for very small molecules (e.g. H2, HeH+) the ...
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1answer
85 views

Am I doing anything wrong when trying to calculate the expectation value in Qiskit on the real hardware?

I am trying to use the method of calculating the expectation values of Pauli operators in Qiskit which I found here. However, the results obtained via IBMQ sampling differ significantly from the exact ...
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1answer
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How to implement Cx mod N unitary

The following links provides circuts for $a\in\{2,7,8,11,13\}$ and $N=15$: https://qiskit.org/textbook/ch-algorithms/shor.html#3.-Qiskit-Implementation https://arxiv.org/abs/1202.6614v3. I am ...
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1answer
97 views

Why after transpiling a Qiskit circuit we obtain a different result?

I am trying to obtain the correct circuit transpiled for the ibmq_london device, as I want to know what the real gates applied in the quantum computer are. I am implementing the QFT circuit for 5 ...
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1answer
50 views

Feedback on Deutsch-Josza alg. homework prob. in Learning Quantum computation using Qiskit [closed]

In Learning Quantum Computation using Qiskit chapter 3.4 I encountered the Deutsch-Josza Algorithm. At the end of the chapter I was presented with a homework problem where the code: ...
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1answer
96 views

How the simulator work?

Recently I focused on how to simulate in classical computer, and I found Qiskit offers qasmsimulator and statevector simulator. ...
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1answer
66 views

What extra functionality is available to an IBM Q Network member over a regular IBM Q Experience user

I've been trying to figure out the extra functionality available to IBM Q Network members that are not available to normal ...
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1answer
46 views

Question About How Qiskit Reset Gate Affects Other Entangled Qubits

I am trying to understand how the reset gate in Qiskit affects qubits its entangled with. Consider the following circuit with qubits $q_0$ and $q_1$: Where circuit240 takes $|0\rangle$ to $a|0\rangle ...
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1answer
67 views

Expectation value of an operator error: Composition is not defined over operators of different dimensions,

I am trying to calculate the expectation value of a customized operator on two similar but differently constructed states $\phi = \phi_2 =\frac{1}{\sqrt{2}}\left( |001⟩ + |011⟩\right)$ which consist ...
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2answers
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Does anyone know of Qiskit source code for a Bernstein Vazirani grover's algorithm for N bits? If so please share

I'm just getting started in the space of quantum computing, I've built a 5 qubit program for Bernstein-Vazirani, but am trying to figure out how to go about building an N bit version of Bernstein-...
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1answer
50 views

What is the difference between Qiskit execute and the IBMQJobManager?

I was researching how to submit multiple pulse schedules/circuits in the same job and came across 2 methods: Executing Experiments with qiskit.execute and ...
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2answers
289 views

Why are IBM QE backend results different from the qasm simulator for a simple quantum circuit?

I have looked at other questions that ask pretty much the same thing such as this and from what I gathered the significant difference in simulation and actual results is due to decoherence and ...
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QFT on timeseries Data and compare results with classical FFT

Intention - To learn and apply QFT on time-series data and compare the result with classical FFT. Data Used - Small timeseries data of 16 points - ...
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1answer
79 views

How to do error mitigation on the ibmq_16_melbourne?

I'm trying to make a calibration matrix using CompleteMeasFitter as in here on IBMQ Melbourne, but I need to use all 15 qubits, which mean it has to run 32768 calibration circuit, far exceeding the 75 ...
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1answer
64 views

Why is import qiskit failing to import in Anaconda Jupyter Notebook

I recently downloaded Anaconda(Python 3.7) on Windows 10 and I am having difficulty importing Qiskit in jupyter notebook. I tried the following line: import qiskit ...
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2answers
51 views

Why is the number of solutions given in Qiskit textbook(Quantum Counting Algorithm) as N-M instead of M?

I'm following the Qiskit textbook for Quantum Counting. We have assumed $M$ as the number of states containing solutions throughout the algorithm but at last, $N-M$ has been taken as the solution. ...
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1answer
91 views

I want to create a depolarizing channel on IBM qiskit

I want to replicate the depolarizing noise channel for a 4 qubit circuit system, where p is the probability for an error. I tried doing this: But I get the error ...
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1answer
24 views

Error code: 3458

I ran my qsvm code on the quantum computer and I'm facing the following error: ...
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1answer
34 views

Qiskit textbook install error

I'm trying to install the qiskit_textbook repository (https://github.com/qiskit-community/qiskit-textbook) and I keep getting this error ...
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2answers
102 views

Representation of rotation operators $e^{-i\theta(I-Z_1\otimes Z_2 \otimes Z_3)}$ about arbitrary axis for $3$ qubits

I was wondering in how to interpret and represent the operator $e^{-i\theta(I-Z_1\otimes Z_2 \otimes Z_3)}$ for a 3 qubit system in a circuit using qiskit. I was thinking I could just perform an ...
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38 views

How do I optimize HHL algorithm in Qiskit?

How do I optimize HHL algorithm in Qiskit? I tried to follow this tutorial on HHL in Qiskit. My project requires solving a very specific type of linear equations $Ax=b$ like the one below. ...
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1answer
53 views

How to append an Instruction to a QuantumCircuit with variable length of QuantumRegisters as qargs?

I think it is a bug but I'm not really sure. Basically, what I'm trying to do is the following: I have an Oracle Instruction which I want to append to my QuantumCircuit, looks as follows: ...
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Is it possible to express u1(λ) through the gates rx, ry, rz while maintaining the phase? In Qiskit for example

Is it possible to express gate u1(λ) through the gates rx, ry, rz while maintaining the phase? Both in principle and in practice (in Qiskit for example)? The single gate rz(λ) is not suitable, because ...
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2answers
59 views

Why do I get positive amplitudes when I create a qiskit StateVectorCircuit from only negative amplitudes?

I am using amplitude encoding to encode my features in a quantum circuit. With this I expect to encode e.g. 32 features in five qubits. For the encoding I use qiskit's ...
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1answer
47 views

Quantum error correction on IBM devices?

I'm wondering if the gate errors on any of the IBM devices are low enough so that we could use some error correcting codes which do not require too many qubits? (such as 5- or 7-qubit codes). Even ...
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2answers
52 views

Installing Qiskit Error: Building wheel for ecos error

How can I fix this error? I am installing the newest version of Qiskit.

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