Questions tagged [vqe]
For questions about the Variational Quantum Eigensolver, a quantum/classical hybrid algorithm that can be used to find eigenvalues of a (often large) matrix H. When this algorithm is used in quantum simulations, H is typically the Hamiltonian of some system. In this hybrid algorithm, a quantum subroutine is run inside of a classical optimization loop.
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VQE for Max-Cut: Low Approximation Ratio (0.2 - 0.5) Instead of Expected 0.7 - 0.9
I am working on implementing a Variational Quantum Eigensolver (VQE) to solve the Max-Cut problem. I am using the approximation ratio (AR) as the metric to quantify the results, which is typically ...
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Trying to run a VQE problem on Qiskit runtime
I am trying to find the ground state of a LiH molecule using qiskit runtime instead of the Estimator primitive. I am basically using the exact code given in the documentation here as a trial. But ...
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Variational quantum eigensolver tutorial
I am looking some good paper and coding tutorial for variational quantum eigensolver.
It would be great if someone can guide me on this?
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How transform a trial variational wave funtion to an appropriate ansatz for VQE?
I have a trial wave funtion as follows:
$$\psi_{trial}=e^{-\alpha r-\beta r^2}$$
where $\alpha$ and $\beta$ are the variational parameters. It gives precise results for a specific system. Now I want ...
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How to use a customized trial wave function in a VQE algorithm?
I'm a beginner in quantum computing, so my question may seem simple. I have a quantum chemistry problem (obtaining ground state energy) in hand that I have already solved it using different standard ...
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The number of qubits of the ansatz does not match the operator
I am trying to run my below code on FakeSherbrooke() system, but I am getting an error as shown below:
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VQE applications which use the Pauli strings containing {I, X, Y, Z}
VQE is a quantum-classical hybrid algorithm which goal is to find the ground state of a Hamiltonian. The most well-known application of VQE is for chemistry simulation. A chemistry simulation can be ...
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How to check if the diagonalizable circuit really diagonalizes the measurement observable?
For a Hamiltonian composed of a list of weighted Pauli strings, to calculate the expectation value, we need to obtain the expectation value of each Pauli string. To reduce the measurement overhead, ...
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Interpretation of output for Portfolio optimization program
I am new to quantum computing, though I am by now familiar with certain jargon but have miles to go before I gain a foothold on the subject. I have been trying very hard to understand and interpret ...
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Gradient of energy in ADAPT-VQE algorithm
In the ADAPT-VQE algorithm (see https://arxiv.org/pdf/1812.11173), step (5) involves measuring commutators of the Hamiltonian with each operator in the operator pool to get the gradient of the energy ...
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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.
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Does anyone have an idea about the execution power of IBM summit for VQE? I'd appreciate sources of papers as well for supercomputer execution
I'm trying to find the execution power of VQE in super computer and I want to know the factors of execution such as iterations, shots, convergence, etc. Please help me and also, I'd appreciate if ...
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Expectation values with finite number of shots with qsimcirq
I was using qsimcirq for VQE to obtain exact expectation values of the energy for a certain Hamiltonian with
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Portfolio Optimization with VQE (Qiskit)
I'm working on a portfolio optimization problem using Qiskit and I'm encountering an error when trying to solve a quadratic program using MinimumEigenOptimizer with SamplingVQE (V1 Primitives). Any ...
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Portfolio Optimization with VQE
I'm working on a portfolio optimization problem using Qiskit and I'm encountering an error when trying to solve a quadratic program using MinimumEigenOptimizer with SamplingVQE. Any insights on what ...
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Variational Quantum Linear Solver
I'm studying quantum computing right now and trying to implement variational quantum linear solver to solve a system of linear equations. From what I have understood from the paper written by Carlos ...
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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 ...
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Using Orbital Optimization VQE
How can I use the OrbitalOptimuzationVQE class in qiskit? I want to find the ground state energy if different molecules using OOVQE but I cannot import the orbital optimization vqe class from qiskit. ...
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Complexity of Variational Quantum Eigensolvers
I am doing research surrounding VQE and am a bit confused about the complexity and its comparison to classical systems. My brief research has yielded me that classical eigenvalue solving is $O(n^3)$. ...
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Prereqs for learning Variational Quantum Eigensolver (VQE)
I am trying to learn Variational Quantum Eigensolver algorithm(s) for a class.
However, I am struggling because I don't understand any of the problems we are trying to solve.
I want to know what I ...
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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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How to combine a VQE circuit with normal qiskit quantum circuit without parameters and give the measured set of qubits to the estimator?
I want to use a parameterized quantum-circuit which is $\text{CNOT}$ with another quantum-circuit that has no parameters, then after a series of gates on the second quantum-circuit, I want to measure ...
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Running VQE code using qiskit_nature on IBM computers
$\texttt{qiskit_nature}$ no longer has the $\texttt{runtime}$ feature and $\texttt{VQEClient}$ function that was used to run a VQE code on one of the IBM computers. I could not find any easy migration ...
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vqe.compute_minimum_eigenvalue API of qiskit produces different eigenstate results for statevector_simulator ands qasm_simulator
I am trying to understand the usage of vqe.compute_minimum_eigenvalue API of qiskit for the statevector_simulator and qasm_simulator. I am only interested in the <...
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How can I Combine Qiskit's VQE Tutorial and TSP Simulator to solve the TSP on a real backend efficiently?
I have a university project where I am trying to solve the Traveling Salesman Problem by using a real quantum backend, rather than just the VQE simulator, as in this tutorial.
I found this code on ...
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Usage of qiskit API MatrixOp.to_pauli_op()
I am quite confused with the MatrixOp.to_pauli_op() API.
I have a hamiltonian, and it is given as input to a
API MatrixOp.
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VQE on Qiskit: getting counts per Hamiltonian term
Consider a VQE calculation (using the QASM backend and on Qiskit) that involves a qubit Hamiltonian with, say, 5 terms. Is there a way for us to get the counts for each of the Hamiltonian terms that ...
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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 ...
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Implementing cphase gate on IonQ through Amazon Braket
I am implementing a VQE algorithm where I need controlled phase gate as part of ansatz circuit. I am using Amazon Braket service. Ionq processor however does not support c-phase gate or phase gate. ...
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Getting a numeric result from the variational quantum eigensolver
I am confused about how the VQE is able to print out a decimal number for the ground state energy of a molecule.
For example, for $\text{LiH}$, the ground state energy I get for an interatomic ...
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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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Need help regarding building a custom VQE
I want to write code for a custom Variational Quantum Eigensolver (VQE) capable of computing eigenvalue(s) for non-Hermitian systems, based on this paper. I have formulated a cost function (provided ...
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Understanding the Role of Qiskit's VQE Code in Light of Pre-calculated Zero-Point Vibrational Energy in Gaussian Files
In the context of quantum computational chemistry, the Qiskit VQE (Variational Quantum Eigensolver) code is often used to calculate the vibrational energies of molecules, including the zero-point ...
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How to update angles
I am struggling to understand the concept of updating angles in a parameterized algorithm.
Assume I have an objective function $x^2+1$ that I want to optimize using QAOA which can handle continuous ...
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Why is it hard to prove complexity bounds for variational algorithms?
I'm not very familiar with variational algorithms, but I've heard people say that they're "heuristic" and it's difficult to measure their performance via complexity analysis. Why is this the ...
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Is Qiskit's Estimator Primitive running PauliStrings in Parallel?
I am trying to run the following code:
...
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Qiskit noisy FakeManila simulator + ZNE
I am trying to run a simple VQE calculation on H2 using FakeManila noise model and ZNE for error mitigation; see code below. The problem is that I can never reach not even close the ground electronic ...
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Variational Quantum Eigensolver (VQE) by scipy minimize in cirq does not work
I tried to make a cirq program calculating an eigenvalue of the observable by VQE. Inspired by the qulacs VQE tutorial, I defined a cost function from the expectation value of the observable with ...
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Efficient gate executing the time evolution of a Hamiltonian using Runge-Kutta method
You can find a minimal working example below.
In particular, I want to replace the scipy.linalg.expm() matrix exponential by a Runge Kutta time evolution method as ...
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Help me to find error in finding Cost Function for SSVQE algorithm [closed]
Q: Build SSVQE's cost function using the following observable: $$O=2II−2XX+3YY−3ZZ\,.$$
This cost function should take in parameters as input. Use the included variational form, with reference states $...
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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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The importance of the ansatz in VQE algorithm
Let's say I have a universal quantum computer that can perform anything.
In this case, any VQE algorithm can use any operation, so no ansatz is needed to implement it.
My question is, is the usage of ...
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Pennylane variational classifier demo - need for padding
In the variational classifier demo from Pennylane, the data loading is performed with
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Ansatz for VQE demonstrating Quantum Advantage
What would be a possible ansatz quantum state in VQE (variational quantum eigensolver [1]) that would demonstrate the quantum advantage of VQE over classic computers? More specifically, I see that VQE ...
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Difference between Qiskit and Openfermion two body integrals
I am struggling with understanding the differences between OpenFermion and Qiskit libraries when it comes to Molecular Data, two body integrals.
For example, I am working with the following ...
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Minimum working example for Qiskit's AdaptVQE
I am trying to implement a simple AdaptVQE in Qiskit. Following the documentation provided by Qiskit, this should be very simple:
...
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Is there a way I can create an ansatz such that the number of 1 is same in all the superposition states? [duplicate]
So I am working with a variational quantum algorithm and I realised that it would be very beneficial if I could create an ansatz where all the states in the superposition have same numbers of 1s. For ...
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Compute molecular vibrational energy of CO2 molecule using VQE
I have to compute the molecular vibrational energy of CO2 molecules using VQE, but I am not progressing; Code on the qiskit website does not work. Does anyone have any working code to find vibrational ...
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Is there a way to find the computational resources required to perform a simulation of n- qubits in Cirq similar to qsim?
I’m trying to model basic spin chains in 1D using VQE (ideal circuit) with cirq and qsim. The models have between 10-20 sites and varying interactions (nearest neighbour, next to nearest neighbour etc)...
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Efficient classical simulation technique to execute this specific quantum circuit
I have a quantum circuit similar to the ones used in VQE methods. One difference is that the angles of the $R_y$ rotations are limited in the range $[0, 0.2]$ (and chosen randomly). In my case, I have ...
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