# 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).

117 questions
Filter by
Sorted by
Tagged with
1 vote
57 views

### Implementing QAOA Hamiltonian for MAX-3-SAT in Qiskit

I have read about how QAOA is used to tackle the MAX-CUT problem and wanted to test my understanding by trying to implement some code to approximate the MAX-3-SAT problem. To do so, I considered the ...
1 vote
23 views

### Calculating state fidelity and space complexity of Minimum Eigen Optimizers (VQE, QAOA and Grover Optimizer) in qiskit

I'm a beginner in using Qiskit and my Computer Science background is not extensive. But I understand the Quantum Physics aspects of it relatively well. I solved a QUBO problem in Qiskit using VQE (...
86 views

### How to implement Qiskit QAOA code on a real quantum computer?

I'm trying to run the QAOA code from Qiskit (https://qiskit.org/textbook/ch-applications/qaoa.html) on a real quantum computer. However, it doesn't work. Here starts my code: ...
• 21
1 vote
52 views

### Interpreting VQE and QAOA based solutions in portfolio optimization

I am going through portfolio optimization using Qiskit. It really looks interesting. The module has both VQE and QAOA algorithms for optimizing the portfolios. In the VQE based solution the ...
• 31
1 vote
17 views

### Error analysis on the approximation of an adiabatic evolution operator by a QAOA circuit

I would like to know what would be the approximation error of a QAOA circuit. Suppose we have time-dependent Hamiltonian $H(t) = (1 - s(t))H_{init} + s(t)H_{prob}$ where $H_{init}$ in an initial ...
• 1,161
46 views

### Does the Lie closure of a set of Hamiltonians describe all unitaries you can generate with them?

Suppose we have $k$ Hermitian matrices $H_1, ..., H_k \in M_d(\mathbb{C})$. Define $\mathfrak{g} = \langle iH_1, ... iH_k \rangle_{\text{Lie}}$ to be the Lie algebra generated by these Hermitian ...
100 views

### Qiskit unable to transpile the circuit for Rigetti Aspen M 1 on AWS

I am trying to run a Qiskit QAOA algorithm on AWS Rigetti Aspen M 1 Backend using qiskit braket provider. However qiskit is not able to properly transpile the circuit ...
• 31
93 views

### For the same operator, when I use qiskit's VQE and QAOA solutions, the results are completely different

Specifically, I can't get the correct result using QAOA，A total of 6 qubits were used in this work，this is part of my code using VQE and QAOA localsim = BasicAer.get_backend('qasm_simulator') ...
• 21
138 views

### Choosing a different optimizer when running QAOA in qiskit

I am trying to reproduce the QAOA example from https://qiskit.org/textbook/ch-applications/qaoa.html and learn how to opt for a different optimizer. The relevant block in the example is (towards the ...
• 515
115 views

### qiskit qaoa.compute_minimum_eigenvalue

I am having some trouble running the compute_minimum_eigenvalue method from qiskit's QAOA: the documentation states that one ...
40 views

### Validating existing QAOA, deprecated solutions on qiskit

I'm currently evaluating a static QC, QML and QAOA approach to solving a combinational problem. My solution with the static QC and QML approach is finished, and all data has been collected. Now, the ...
• 147
229 views

### Qiskit compute mean expectation value

I want to calculate the mean expectation value of an PauliSumOp within qiskit after I executed a QAOA Circuit. My approach is the following: ...
45 views

### Find minimum eigenvalue of an Ising Hamiltonian combined with Error Mitigation

I am currently working on a variation of the Traveling Salesman Problem. For which I use the QUBO(Quadratic Unconstrained Binary Optimization). Within Qiskit there are potent functions to obtain the ...
53 views

### Understanding QAOA from Basics/scratch

Recently after working on QAOA with finance and graph coloring problems. I have started exploring the QAOA from scratch. I would like to understand the QAOA derivation mathematically and have started ...
62 views

### What are the important parameters when it comes to VQE algorithms in qiskit?

So I wrote an algorithm for a quadratic problem (qubo) and try to solve it. My question is why I don't get the correct results when running my algorithm on a quantum computer like IBM_manila. In the ...
• 21
55 views

### Given a cost Hamiltonian, how to determine number of qubits required for running QAOA?

Say I have a cost Hamiltonian for an optimization problem which involves an objective function, and constraints (in particular, section III of this paper 1, on page 3). I’d like to determine the ...
• 121
200 views

### Why do we decompose the hamiltonian into Pauli strings to measure the expectation value?

Measuring the expectation value of a hamiltonian is an essential step in some algorithms like QAOA. I noticed that the procedure always starts with decomposing the hamiltonian into a sum of Pauli ...
• 237
78 views

### Why does QAOA's performance monotonically increase as p increases?

From A Quantum Approximate Optimization Algorithm - Farhi et al. The Quantum Approximate Optimization Algorithm has the key feature that as p increases the approximation improves. We contrast this to ...
• 237
75 views

### Why do we add the cost function as a phase in QAOA?

For QAOA, my understanding is that after we derive our cost Hamiltonian: $H_c|x$>$=C(x)x$ where $C(x)$ is the cost function on input x. We exponentiate it: $e^{-iH_c\theta}$, so we can simulate ...
• 237
102 views

### Hardware efficient ansatz versus Alternating Layered Ansatz

I'm reading a paper Cost function dependent barren plateaus in shallow parametrized quantum circuits. There they introduce what is called Alternating Layered Ansatz (ALA). It is said that: The ...
• 249
66 views

### How to optimise QAOA

I have a similarly naive question about the classical part of the optimisation in the Quantum Approximate Optimization Algorithm. Specifically, the cost function is given prescribed as \begin{align} ...
134 views

### How to theoretically compare the complexity of quantum and classical algorithms?

I am working on reducing an NP class problem to a QUBO so can be solved with QAOA. I know that there is not a practical way to compare the performance as there is no QPU with enough qubits. I am doing ...
• 81
1 vote
144 views

### Tweak the parameter p of QAOA in qiskit

I am solving a QUBO using QAOA. It works flawlessly with default parameters for smaller instances of the problem, but my RAM is saturated when I try to solve a problem of size 15. I suspect this can ...
• 81
1 vote
202 views

### QUBO defined in Qiskit/DOcplex: how to solve it using Pennylane?

I have a complex Integer Linear Programming model defined in DOcplex/Qiskit representing a combinatorial optimization problem. Using the Qiskit utils, it is possible to covert it to either an Ising ...
150 views