# Questions tagged [qaoa]

For questions about the Quantum Approximate Optimization Algorithm (QAOA), first introduced in Farhi, Goldstone, Gutmann 2014 (https://arxiv.org/abs/1411.4028).

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### Why is my graph wrong when trying to visualize the max-cut in qiskit?

I think my QAOA code is correctly solving the max-cut but the visualization is wrong. I am working on solving the Max-cut problem using QAOA. I started small-scale with a 5 node bipartite graph. I ...
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1 vote
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### How to map a constraint to the output of a binarized continuous Quadratic Optimization problem?

I have the following quadratic cost function $$J(t) = \int_{0}^{t} \left[ z(\tau)^\ast A z(\tau) + w(\tau)^\ast B w(\tau) \right] d(\tau)$$ where $w = -Rz$ and A and B are matrices whose values are ...
1 vote
56 views

### SparsePauliOp' object has no attribute 'primitive_strings' warning for a max-cut problem using QAOA and MinimuEigenOptimizer

I am using Qiskit to implement QAOA for a max-cut problem. I am using inbuilt qiskit implemetation of QAOA and, the MinimuEigenOptimizer. The MinimuEigenOptimizer.solve() throws the warning. ...
27 views

### Cost function lagrangian equality penalty in QAOA

I try to apply the QAOA to a given problem composed of $x_1,\dots,x_n$ boolean (0/1). Each variable $x_i$ is then encoded on one qubit. There is the constraint on theses variables that : \begin{...
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### How to apply the QAOA in such a QUBO problem?

It was a rainy night, bro was learning QAOA and stuck on such a problem. For example, 100 CAD is exchanged for USD, USD is exchanged for EUR, and EUR is then exchanged back to CAD. The final value in ...
• 23
131 views

### ValueError: The number of qubits of the circuit (127) does not match the number of qubits of the ()-th observable (4)

I am quite new to qiskit and i am trying to build a qaoa for portfolio optimization, but i get this error and i am not able to resolve this issue: ValueError: The number of qubits of the circuit (127) ...
1 vote
43 views

### How to easily get the number of qubits required when using QAOA from qiskit_algrithms?

I would like to know if there is a easy way or native solution to retrieve the number of qubits that is required when using QAOA from qiskit_algorithms package to ...
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### Problem with understanding advantage of QAOA over bruteforce

I am trying to figure out with QAOA alghorithm. I use the example from this qiskit notebook https://github.com/Qiskit/textbook/blob/main/notebooks/ch-applications/qaoa.ipynb. I have the question to ...
69 views

### Feasibility of Applying QAOA to Quantum Chemistry Calculations

Is it possible to apply QAOA (or quantum alternating operator ansatz) to quantum chemistry calculations for NISQ devices? If not, why? If it is possible, why is it not commonly seen?
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### Optimization in QAOA should only return global minimum?

I am working on a project dealing with QAOA and I have some theoretical question about this last one. I hope I could find someone familiar with the field. QAOA is usually used to solve combinatorial ...
1 vote
33 views

Attempting to understand some basics here before developing an quantum algorithm. Would of you be able to help clarify the following definitions I attempted to construct which compare the two ...
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1 vote
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### "Session has been closed" Error in solving Maxcut problem by QAOA

I am trying to run this code- https://learning.quantum.ibm.com/tutorial/quantum-approximate-optimization-algorithm same way as they mentioned. After running this code, my qiskit Dashboard show 10-12 ...
50 views

### How to interpret result for an OR problem solved in Qiskit

I solved "01 KnapSack problem" in Qiskit optimization module. Though the iterations doesn't gets converged but I got an answer (may be infeasible). But my question is that how to interpret ...
294 views

### How to convert a combinatorial optimization problem into a problem hamiltonian

I want to ask how I can convert any combinatorial optimization problem into a Problem Hamiltonian, since such a conversion is needed in order to solve an optimization problem on quantum hardware (e.g. ...
1 vote
78 views

### How to correctly compute expectation value in QAOA?

In QAOA after prepating $|\psi(\gamma, \beta) \rangle$, expectation value $\langle \psi(\gamma, \beta)|H_c|\psi(\gamma, \beta) \rangle$ is computed. In tutorials, I see two approaches to this ...
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1 vote
28 views

### Do encoding schemes for variational algorithms apply to annealing methods (e.g. DWave)?

I understand there are some efficient encoding schemes for variational algorithms, that attempt to approximate the variational state using fewer qubits. I'm thinking of 2 papers in particular, which ...
57 views

### Solving optimization problems on real quantum hardware

I want to know how to solve a 01 Knapsack problem (or any optimization problem) on real Quantum Hardware only. I don't want to use an Application class or any classical simulation technique. If anyone ...
18 views

### Can dimensionality reduction be used to simplify data before using an optimization algorithm?

I am attempting to use a quantum algorithm, like a QAOA, to solve an optimization problem. I saw that qPCA can be used to simplify datasets and make them easier to analyze. Can quantum optimization be ...
1 vote
215 views

### How to convert QUBO (with non-zero diagonal elements) to Maxcut?

I want to solve QUBO with non-zero diagonal elements in matrix Q using QAOA. But I want to solve for a large enough problem size (30+ variables) and hence want to divide my circuit into subcircuits. ...
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1 vote
149 views

### Combinatorial optimization problem via VQE instead of QAOA

I'm studying about the hybrid quantum algorithms and I have a question about the VQE and QAOA. It seems like QAOA is a part of VQE that use a certain ansatz for solving combinatorial optimization ...
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1 vote
79 views

### How to run the post processing and return results in QAOA?

As suggested in TranspilerError: 'Number of qubits (40) in QAOA is greater than maximum (30) in the coupling_map' issue. I managed to submit the job to IBM quantum and the circuit runs successfully. ...
456 views

### TranspilerError: 'Number of qubits (40) in QAOA is greater than maximum (30) in the coupling_map'

Hi Ive been trying to solve a custom PO problem using QAOA and I ran into this particular error. As per my understanding,this is due to the limitation of the simulation hardware. But as per the ...
1 vote
22 views

### What is the benefit of using a Multi Angle QAOA?

I am currently doing some research that requires a quantum optimization algorithm. I have been looking at types of quantum algorithms to see which one would be most useful for my problem and ...
351 views

### Are there techniques to reduce the number of Pauli strings in a Hamiltonian?

Suppose $H=\sum_{i \in n} c_i h_i$ is a generic Hamiltonian. Is there a way to find $\tilde{H} = \sum_{j \in m} d_j h_j$ where $m < n$ is a user defined cut-off parameter that would accurately ...
1 vote
98 views

### How to solve a QUBO problem by QAOA algorithm with Qiskit Optimization on a real quantum resources/hardware?

I am new to quantum computing, and I am following this tutorial trying to use Qiskit Optimization 0.6.0 to solve a simple quadratic problem by applying QAOA algorithm. As stated in the tutorial, I ...
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1 vote
61 views

I want to decompose a two-qubit unitary gate $U$, $$U = e^{-i \cdot \frac{t}{2} \cdot Z_1 \cdot Z_2}\,,$$ where $t$ is an angle. I already know the right decomposition but Qiskit gives me an ...
1 vote
77 views

### Question on efficiency of HOBO Quadratization and other depth reducing techniques

I am having trouble understanding some concepts in Quadratizing a high order polynomial. I am reading the review "Quadratization in Discrete Optimization and Quantum Mechanics" . I would ...
1 vote
293 views

### How to solve quadratic programming problems with continuous variables and continous constraints by using quantum algorithms?

enter image description here Here is my optimization problem I solve with classical optimization using DocPlex but I want to solve using quadratic program using Qiskit and QAOA as solver ...
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### Why don't we start evolution with ground state in QAOAnsatz?

The adiabatic theorem states that we can start from an eigenstate, slowly change our Hamiltonian and still remain in the eigenstate. In the vanilla QAOA we start from $|+\rangle^n$, which is the ...
1 vote
245 views

### Error code 1217, Message: Reduce time between submitting subsequent jobs in a session

I tried running a piece of Qiskit code to minimize a Hamiltonian using QAOA. I tried running the same piece of code that I had used earlier in the IBM Quantum system 'ibm_nairobi' which gave me the ...
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1 vote
244 views

1 vote
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### Link between AQC and QAOA

I try to understand precisely the link between AQC and QAOA, through the Trotter-Suzuki formula. A similar question is Derivation of QAOA from AQC, but I was asked by moderators to post my question ...
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1 vote
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### How to add a circuit layer after computing QAOA layer

I have used the Qiskit-based QAOA function to solve a combinatorial problem tsp, and I want to append a circuit after the QAOA layer, is there any way to do that? Qaoa
144 views

### How to use Warm-Start QAOA in QisKit to solve non-convex QUBO problem?

I have a non-convex QUBO problem that I'd like to solve by warm-starting QAOA with a solution obtained from a continuous relaxation solution obtained by a classical algorithm. The specifics of the ...
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### Recent experimental demonstrations of variational quantum algorithms?

I am interested in the recent experimental demonstrations of variational quantum algorithms. Can someone please provide me with a list of references of recent experimental demonstrations of ...
1 vote
48 views

### 'Continuous' (Classical) Cost function for QAOA

I have some combinatorial optimization problems which I would like to analyze using QAOA. These problems are coming from various applications in scientific computing such as solving PDEs. Some of ...
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