# Questions tagged [optimization]

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

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• 13.1k
366 views

### How does the classical optimization of the angles $\gamma$ and $\beta$ in QAOA work?

I have been trying to implement QAOA with classical optimization of the angles $\gamma$ and $\beta$, but I I'm failing at the classical part. In paper Quantum Approximate Optimization Algorithm: ...
• 519
1 vote
128 views

### Qiskit: Error when importing libraries for ADMM optimizer

I would like to try and ADMM optimizer as shown in Qiskit Tutorial in Quantum Lab. Firstly, I imported necessary libraries (copy/paste from the Tutorial): ...
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I prepared a quadratic optimization task with binary and integer variables and linear and quadratic constraints. I fed it into QuadraticProgram in Qiskit. After ...
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### Quantum Circuit Optimization with Machine Learning [closed]

I read some paper about Quantum Circuit Optimization but I am on a low level. And have some experience in ML. But what I don't understand is it possible that ML can help to optimize Quantum Circuits ...
• 141
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### Implementing a circuit that returns $|01\rangle$ and $|10\rangle$ with equal probability

Using Python how can I implement a quantum circuit that returns $|01\rangle$ or $|10\rangle$ using only $CX$, $RX$ and $RY$ gates, starting with random parametric gates as parameters and optimizing it ...
282 views

### Qiskit sample - Portfolio optimization

I've recently tried to run this sample from Qiskit (Portfolio Optimization) I was able to change RandomDataProvider to YahooDataProvider and able to run it on real stock prices. However, there is one ...
157 views

### What is the query complexity of the QUBO algorithm?

What is the complexity of the quantum unconstrained binary optimization (QUBO) algorithm in the number of queries to the quantum processor? To clarify, I'm asking about the complexity on quantum ...
• 131
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### Optimization using Quantum Logics

Is it possible to solve the following kind of optimization using Quantum Computing? Minimize 5*x1 - 7*x2 binary x1 x2 If yes, is it possible to have a sample code ...
• 183
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### How can I solve the problem of optimisation the quantum computer?

I am trying to solve the problem of optimization (VRP) with genetic algorithm and quantum computing in the platform IBM Q Experience. But I am unable to advance on this. How can I do it? According to ...
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### Qiskit Portfolio Optimization Application

I recently got flung into the world of quantum computing and I'm a beginner at coding. I was assigned to do the Portfolio Optimization tutorial of the Qiskit Finance Tutorials and input real data. ...
• 81
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### Computing the expectation values of a Hamiltonian constructed from a cost functions in combinatorial optimization

One of the main steps in Hybrid Quantum algorithms for solving Combinatorial Optimization problems is the calculation of the expected value of a hermitian operator $H = \sum{H_i}$ (where $H_i$ are ...
163 views

### How to stop optimization of a circuit during transpiling in web-interface of IBM Q?

I was playing with approximation of gates with Clifford+T group on IBM Q. Everything works well on simulator, however, when I tried to run my circuit on actual quantum processor, a transpiler ...
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1 vote
181 views

### Layout Method in qiskit

Using transpile with optimization_level = 3, which is the layout method used by default?
• 13
1 vote
171 views

### SPSA max_trials

I'm using SPSA as an optimizer in VQE algorithm. The code runs on ibmq-qasm-simulator. I've set SPSA max_trials parameter to 500, but, when I run the code, it makes ...
54 views

### van Dam's proof for adiabatic optimization and graph diameter

My question concerns a proof in https://people.eecs.berkeley.edu/~vazirani/pubs/qao.pdf, "Limits on Quantum Adiabatic Optimization - Warning: Rough Manuscript!" by Wim van Dam and Umesh Vazirani. It ...
• 311
1 vote
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### Is there a limit to the size of problems that your simulators can run on Qiskit Aqua?

I'm trying to solve QUBO problems using Qiskit QAOA and VQE solvers. However, I have the experience that I can only solve small problems. I tried with both QAOA and VQE and both experience the same ...
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### How to convert QUBO problem to Ising Hamiltonian?

According to paper Ising formulations of many NP problems an unconstrained quadratic programming problem $$f(x_1, x_2,\dots, x_n) = \sum_{i}^N h_ix_i + \sum_{i < j} J_ix_ix_j$$ can be expressed ...
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### What are the differences between the different transpiler optimization levels in qiskit

I am currently running a simple algorithm using Qiskit and I am running it for various transpiler optimization levels (0-3). I wish to know what exactly occurs differently when for example I run the ...
• 128
720 views

### What is Ising Hamiltonian ? What its role in Portfolio Diversification?

I am asking this question with reference to this https://github.com/Qiskit/qiskit-iqx-tutorials/blob/master/qiskit/advanced/aqua/finance/optimization/portfolio_diversification.ipynb Happy to know new ...
• 167
1 vote
255 views

### What is the risk factor on IBM's portfolio optimization notebook?

In the notebook "portfolio optimization" on IBM's platform the goal is to calculate the optimal stock selection using a classical and a quantum algorithm (VQE). A random portfolio is generated and ...
• 11
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### How can I implement partial transpose on a variable in Picos (Python, trying to solve an SDP)?

I try to optimise a quantity via an SDP. I optimise over all PPT measurement operators and hence have the constraints $\Pi_k^{T_B} \succeq 0$ (PPT) for my measurement operators. The part of the code ...
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1 vote
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### Quantum algorithm for binary assignment problem

Based on the properties of the qubit, how could I solve this problem: I have 3 person A B C and 2 taxis T1 and T2 A and B are friends B and C hate each other A and C hate each other How could I ...
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### How does the fact that the output of a quantum circuit cannot be efficiently simulated classically help for optimisation?

This question refers principally to the article where for a low-depth circuit QAOA, the output cannot be efficiently simulated classically. I am wondering how this kind of quantum supremacy matters ...
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332 views

### How to implement NM Algorithm for Variational Quantum Eigensolver?

First of all: thanks for reading again. I appreciate the feedback I have gotten from this community the past weeks as I started to feel ready to ask questions about quantum computing topics. I am ...
91 views

### How to tell if the ground states of two Hamiltonians are solutions of the same optimization problem?

Let's say, that we have an optimization problem in the form: $$\min_x f(x) \\ g_i(x) \leq 0, i = 1, ..., m \\ h_j(x) = 0, j = 1, ..., p,$$ where $f(x)$ is an objective function, $g_i(x)$ are ...
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Let's say, that we have an optimization problem in the form: $$\min_x f(x) \\ g_i(x) \leq 0, i = 1, ..., m \\ h_j(x) = 0, j = 1, ..., p,$$ where $f(x)$ is an objective function, $g_i(x)$ are ...