Questions tagged [qiskit]
Qiskit is an open source SDK for working with quantum computers at the level of pulses, circuits and application modules. If appropriate, also use the [programming] tag. Please include the version of Qiskit you use when using this tag.
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How to see the effects of the depolarizing channel in qiskit?
I am playing around with adding noise to quantum circuit simulation using qiskit_aer.noise.NoiseModel(). My code creates a quantum circuit and simulates it with ...
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Materials for Qiskit Exam
I spent a few months studying from the following materials but still failed the Qiskit exam (38/60 = 63%). I will be retaking next week so I'm looking for recommendations for any materials I may have ...
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What does adding depolarizing error on a Hadamard gate mean mathematically?
I have a quantum circuit as the following picture. Now I add the depolarizing error on the Hadamard gate using the following code in Qiskit.
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Comparative analysis of TensorFlow-Quantum, Pennylane, and Qiskit, to implement quantum CNNs
I am currently working on a project wherein I have to implement a Quantum Convolutional Neural Network. The best options for NISQ devices are hybrid algorithms, so I will try integrating quantum ...
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Why is Qiskit's QASM simulator giving me incorrect result with VQE?
In the code below, I am using VQE without noise to calculate the minimum expectation value of the two-qubit operator X^X. I get the correct result when I use statevector_simulator but do not get the ...
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What is the gate order in QuantumCircuit.data?
I'm trying to print the quantum gates in a circuit using the QuantumCircuit.data. However, the printed quantum gate order is not the same as the drawing. For example, in the QFT5 circuit generated ...
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Compatibility of partial_transpose in Qiskit
I need to calculate the negativity of a density matrix; in doing so on Qiskit I stuck on the problem of computing the partial transpose for a problem of compatibility.
Basically I extract my density ...
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3
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Why does my quantum circuit run so slow on a real IBM quantum hardware?
I have created a very simple circuit on qiskit to produce a Bell state:
bell = QuantumCircuit(2)
bell.h(0)
bell.cx(0, 1)
bell.measure_all()
And I then run it on a ...
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Qiskit, Statevector.from_label
I apply Grover's on an eigh qubits circuit
I just want to amplify the states whose qubits 6 and 7 are |1>
The following test works (the state 11011001 is correctly amplified)
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83
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Modular addition in Qiskit
I want to implement the Jordan gradient estimation algorithm in Qiskit. I need a unitary operator $U_f$ that performs as follows:
$$U_f: |x_1\rangle |x_2\rangle \cdots |x_d\rangle|y\rangle \...
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How does the Qiskit AerSimulator performance scale with the circuit depth?
The performance of a full-statevector simulation by the Qiskit AerSimulator scales of course exponentially with the number of qubits, since the dimensionality of the Hilbert space where an $N$-qubits ...
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IS my QUBO too big for QAOA using IBM Quantum computer?
On qiskit, I have defined a QUBO, called qp as follows:
...
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How to apply error-correction to the swap test circuit?
Swap test is a simple quantum circuit to measure the inner product of two quantum states [Wiki: swap test], it only contains three quantum gates. However, due to the error in the real quantum computer ...
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How to Find a circuit that evolves from one density matrix to another(qiskit or cirq)
given two density matrices, dmBefore and dmAfter, I want to generate(find) a circuit in Qiskit or Cirq that starting initaliazed with dmBefore ends with dmAfter after it's execution. Is it possible?.
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How to implement a doubly controlled phase gate?
I'm trying to implement a doubly controlled phase gate using Qiskit. I'm aware of this proposed solution, but it's not working on my Google collab notebook. For some reason, I cannot import the "...
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How to calculate the state overlap of two quantum circuits?
Given two parametrized circuits, is there a way of calculating the state overlap of the two of them? I have seen that with Qiskit you can do it through this class: https://qiskit.org/documentation/...
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Can someone explain the behavior called "Aer fast expectation" of Qiskit simulators?
Earlier I asked a question on why statevector_simulator ignores the number of shots when calculating the expectation value of an operator using ...
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Qiskit transpiler error: Unable to translate
This code worked in a previous version of ibmq_simulator and, I think, it works with qiskit_aer, but it doesn't work here and I don't understand the error message. The issue is there is no "path&...
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How to enable qiskit logging? Where is the log file?
I'm trying to debug a qiskit circuit that won't "unroll." Looking at the source code, there are a log of logging calls but they aren't enabled. How can I enable logging in qiskit? Where is ...
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Why don't I receive the output I expect?
I tried to test the Bitflip code using Qiskit. So, see my code below, build the circuit and initialised the first qubit in the state $\biggl[ \frac{1}{\sqrt{3}}, \sqrt{\frac{2}{3}} \biggr]$.
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How to augment a QASM circuit for orbital rotation
Could anyone advise on how to properly augment the hamiltonian circuits in https://github.com/CQCL/ethz-hackathon22/tree/main/benchmarking/circuits for orbital rotation ? https://poe.com/s/...
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VQE for Vibrational ground state energy
I was reading this article. In this article, they calculated the vibrational energy of CO2 and NH3 molecules using VQE, and I checked qiskit documentation for finding Vibrational energy using qiskit. ...
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How to "eliminate" some components of the state vector?
I have $n*k$ qubits. At the very beginning the length of the state vector is $2^{nk}$.
After some manipulations (Qiskit circuit) I reduce it to $k^n$ and it looks like
$a|1...\rangle +a|0...\rangle ......
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GPU Support for Qiskit's SPSA Optimization Algorithm
I am using Qiskit's SPSA optimization algorithm to find the ground state energy of various lattices (fermi-Hubbard model) by running different circuits through it and having the algorithm modify the ...
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Hamiltonian of Bose-Hubbard model
In https://medium.com/qiskit/introducing-bosonic-qiskit-a-package-for-simulating-bosonic-and-hybrid-qubit-bosonic-circuits-1e1e528287bb , could anyone explain the rationale behind the use of ...
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Find the number of iterations for Amplitude Amplification to get the correct states amplified
I'm trying to use Grover operator in Qiskit (more precisely to perform Amplitude Amplification) but I'm facing some problems. I'm experimenting the Quantum Amplitude Amplification in order to amplify ...
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Qiskit experiments on qiskit IBM runtime [duplicate]
I'm trying to perform a state tomography on a quantum circuit using Qiskit experiments. I was able to perform the tomography on the AerSimulator but have still not been able to do the tomography on ...
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state_tomography_circuits error
I build a QuantumCircuit named qc, I want to generate state
tomography circuits to evaluate fidelity of simulation. I used code,
...
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Rotations with angle 0 after transpiling with qiskit
When using qiskit to transpile a circuit sometimes there is a gate Rz(0.0)in the result. I wonder 1) why this happens and 2) what does it mean for the executed ...
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How to implement Shor's 9-Qubit-Code in Qiskit?
I am new to qiskit and currently trying to implement Shor's 9-Qubit_Code. I am trying to orient my code on the example given in the official qiskit-tutorial and so far I have the following:
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How does Qiskit/Qasm simulate the density matrix of up to 30 qubits?
The full density matrix of 30 qubits contain $2^{30}$ states. How does qiskit/qasm implement this without storing and computing the full $2^{30}$ density matrix of possible state coefficients?
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how to convert a qiskit circuit to pauli strings
I have a qiskit quantum circuit that i want to convert to pauli strings (coefficients,observables) so that i can use it to build a hamiltonian. I did not see any methods in qiskit quantumcircuit ...
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Defining an oracle with Qiskit
I have a 8-qubits circuit whose final vector state may be for instance:
$$
\frac{\sqrt{2}}{4} |00010101\rangle+\frac{\sqrt{2}}{4} |00101010\rangle+\frac{\sqrt{2}}{4} |01010110\rangle+\frac{\sqrt{2}}{4}...
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How can I find the documented T1 time of a retired IBM system?
I need to find the published mean T1 time for the 'ibm_oslo' system that I used in an experiment a while back. Unfortunately, that system has now been retired and there's seemingly no way for me to ...
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Are there qiskit or stim examples of how to decode a subsystem code
I can manage decoding a stabilizer code in qiskit and stim. I'd like to try a subsystem code next. For a stabilizer code, all stabilizers commute so simultaneous measurement of these produces ...
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Unitary matrix knowing input and ouput states
Input: n qubits after H gates.
Output, after measure: the n different bit strings of length 2^n with just one 1, with same probabilities.
Or said differently:
Input state |phi0>=(1,1,...1)/2^n
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Is it possible to use GPU backends with `Statevector.evolve`and `DensityMatrix.evolve` method?
I find it useful to use the Statevector.evolveand DensityMatrix.evolve methods as a shorthand to using the Aer simulators with <...
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How to join different quantum circuits into one big circuit on specific qubits in qiskit?
I have a quantum circuit that loads the data and is acting on qubit q0,q1,q2 then another circuit that does the same on q3,q4,q5 ...
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python code to approximate an arbitrary 2*2 unitary matrix with gates H,T and Z
I'm new to programming, tried different options, compiled programs myself, took them from websites, but they didn't work, for example, the program:
...
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In the qiskit QFT demonstration, how to implement CPHASE between Q0 and Q1?
In the qiskit example for QFT demonstration the ibm_q_bogota is used, it has the following layout:
in the same time the measurement circuit for QFT demonstration is:
For such a linear layout how is ...
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The amount of clbit arguments 0 does not match the instruction expectation (16)
I have a quantum circuit of 16 qubits, and I am running Amplitude Estimation on that, my final qubit to measure is 15th, so I do this
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How to best represent 5-Qbit codeword operator in Qiskit [duplicate]
We learned that in the 5-Qibit error correcting code, the logical zero state $ | \bar{0} \rangle $ is encoded in the form of $ \frac{1}{4} (\mathbb{1}+M_0)(\mathbb{1}+M_1)(\mathbb{1}+M_2)(\mathbb{1}+...
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Grover, Qiskit, general definition of "good state"
Trying to implement Grover under Qiskit I found an example with
good_state = ['110','101']
For a given $n$ it possible to define good_state as "any string of $...
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qiskit textbook code throws RuntimeError: IBMBackend.run() is not supported in the Qiskit Runtime environment
I am trying to run the quantum communication algorithm from qiskit textbook "Entangled States" using my IBM API key, however, it throws the error ...
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Nonsensical projection of initialized qubits in Qiskit
I wanted to try Qiskit by setting up two qubits initialized to $ | 11 \rangle $ or $ | 01 \rangle $ and two classical bits to measure those two initialized qubits.
For this simple demonstration, I ...
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Exponential of SparsePauliOp in Qiskit
Since qiskit.opflow has been deprecated, the way I used to generate a UCC ansatz was to use ...
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199
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What are the differences between the two Estimator in the qiskit
Recently, I have been completing a VQE code and implementing the VQE algorithm for noisy models. However, during this process, I discovered that there are two types of Estimators provided in different ...
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Qiskit primitives with commuting observables
Is there a way of bundling commuting observables in qiskit primitive estimator to save the number of shots?
With the new feature of Qiskit primitives, it is easy to sample observables for a specific ...
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How to improve the state fidelity of state tomography in qiskit
I want to simulate state tomography on a 8 qubit state. I use the example https://qiskit.org/ecosystem/experiments/manuals/verification/state_tomography.html as a guide.
My problem is that I get a ...
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In what order does Qiskit assign parameter values?
It seems that "assign_parameters" method introduces the values of the parameters in alphabetical order of different "ParameterVector"s' names. Here is a simple example:
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