Variational Quantum Eigensolver (VQE)

Ansatz Circuit (2-qubit)

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VQE Energy (Ha)
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Exact Ground State
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Error (mHa)
Adjust parameters and evaluate.

Energy Landscape E(theta1, theta2)

Color: blue=low energy (ground state), red=high. White dot=current params, green path=optimizer trajectory.

Optimization Progress

100

Potential Energy Curve: H2 Molecule

VQE finds the ground state energy of the hydrogen molecule (H2) at each bond length. The minimum of the curve gives the equilibrium bond length (~0.74 Angstrom) and bond dissociation energy. This is the canonical near-term quantum computing application: simulating molecular electronic structure.