# Questions tagged [optimization]

For questions concerning how to improve quantum computers on different aspects like performance, efficiency or fault-tolerance.

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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 ...
32 views

### Maximisations over LOCC measurement protocols

I have a quantity that I want to calculate by maximising over LOCC measurement protocols. How does one even approach this problem, both analytically or numerically? Has any work been done on the same? ...
156 views

### Does optimization via Hamiltonian evolution have an analogy like gradient descent?

I'm trying to find out, if there is a simplified concept to understand what is occuring during quantum annealing/ Falqon/ Hamiltonian evolution like algorithms. During classical gradient descent ...
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### Transpilation error: CircuitError: 'The amount of qubit(0)/clbit(0) arguments does not match the gate expectation (2).'

I am trying to implement a algoritm that reduces the number of qubits required for MAXCUT optimization. I need to create a custom gate that encodes a diagonal unitary matrix where the diagonal ...
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### AttributeError: 'ADAM' object has no attribute 'optimize'

I have imported ADAM optimizer in the following way: from qiskit.algorithms.optimizers import COBYLA, ADAM, SPSA, SLSQP, POWELL, L_BFGS_B, TNC, AQGD Afterwards, I ...
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### Interpretation of rounding the output of a quantum annealing solution for optimization problems?

I understand that quantum annealing approaches output a distribution of results of 0's and 1's for thequantum state. I'm wondering if this can be interpreted in the following way: For each qubit, we ...
1 vote
101 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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### Reusing Parameters for Multiple Runs with Qiskit's SPSA Optimization

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 ...
1 vote
296 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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1 vote
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### Why is quantum annealing not used in optimization for variational quantum algorithms?

I have been learning about variational quantum algorithms and encountered that none of the articles talk about using quantum annealers for optimization of the parameters ? I have however encountered ...
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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 ...
33 views

### Why is "reducing Hamiltonian energy" also optimizing a Quantum Machine Learning model?

From what I observed, most hybrid qml architectures surround the ideas of Hamiltonian states, and it seems like our goal to optimize a circuit is to keep energy states as low as possible. But why is ...
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1 vote
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### Quantum optimization and correlation function

If one imagines the nodes of the classical weighted graph as atoms, and paths between them as bonding strength, then to find the shortest path in the weighted graph, can one also look at the minima/...
56 views

### Parallelize estimation of expectation values in Qiskit

Edit I tried using python multiprocessing library. The result with 8 cores isn't always faster than the original script that uses only one core. How can i improve the algorithm? Suppose i've a matrix ...
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### Quantum Annealing on IBMQ using Qiskit-Pulse

Qiskit-Pulse is the analog level control SDK of IBMQ hardware. Is it possible to implement an adiabatic annealing protocol/algorithm on IBMQ hardware using Qiskit-Pulse? Not asking about QAOA, which I ...
1 vote
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### What's the case when parameter-shift rule does not hold?

When the parameterized unitary is of the form $e^{-i\theta V}$, where $V$ is a Hermitian operator of the unitary, we can use parameter shift rule to calculate the gradient. In this paper, it says: &...
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1 vote
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### Comparing BQM and CQM solving for a tree-path problem

I'm currently working on a project for my thesis regarding BQM and CQM optimisation for a path problem. Without going too much on the details, here's some info: the structure is a tree, where all the ...
1 vote
280 views

### Knapsack problem formulation

I would like to use a knapsack problem formulation based on Lucas paper. Namely, I try to implement the following math formula for Hamiltonian $H =H_A + H_B$, where H_{B} = -B\sum_{i=1}^{n}v_{i}x_{i}...
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### SLSQP optimizer(scipy.minimize) doesn't update parameters

I'm trying to find optimal parameters that minimize the cost functions. In cost function, it calculates the classical-fisher-information at a certain point(phi[0] = np.pi). Cost-function takes 3-...
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1 vote
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### Running multiple amplitude estimations simulations

I am working on a mini project investigating the scalability of quantum computing in the context of option pricing. I have been following the above Finance API from Qiskit as an introduction, however, ...
166 views

### Converting Ising Hamiltonian to a Circuit in Qiskit

I tried to solve a 2-node TSP (travelling salesman problem) by implementing QAOA on Qiskit. The graph looks like: Then I used the related Qiskit functions to convert the graph to the QUBO and map it ...
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### Building a problem unitary circuit for QAOA on Qiskit

I am trying to build a circuit for QAOA that solves a Traveling Salesman's Problem, which can be represented as a complete graph with 4 nodes. After formulating the problem as a QUBO and mapping it ...
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### Python code for D-Wave Annealer

In the below screenshot, I am aware of resolving the issue by reducing num_reads as the annealing time is exceeding my allowance. Although it works, my question ...
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1 vote