vqc

Train a variational quantum classifier on tabular data with parameter-shift gradients.

30|2|Updated Apr 16, 2026
One-click install
npx skills add https://github.com/unitarylab/quantum-skills --skill vqc
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: vqc
Source: https://github.com/unitarylab/quantum-skills/tree/main/algorithms/quantum-machine-learning/vqc
Command: npx skills add https://github.com/unitarylab/quantum-skills --skill vqc

SYSTEM DOCUMENTATION & REQUIREMENTS

💡 This Skill requires unitarylab, and includes scripts (resource) components.

What problem does it solve?

Classifies tabular data by leveraging a Variational Quantum Classifier (VQC) trained with data re-uploading and the Parameter Shift Rule to produce interpretable class logits from a small quantum circuit.

Core Features & Use Cases

  • Data re-uploading encoding of 4 features on 4 qubits per layer to preserve input information across depth.
  • Trainable Ry rotations with a CNOT ladder enabling expressive quantum circuits for classification.
  • Exact gradient estimation via the Parameter Shift Rule, enabling gradient-based optimization with Adam.
  • Demonstrations on the Iris dataset (4 features, 3 classes) and multi-layer quantum-classical training workflows.

Quick Start

Run the included script to train the VQC on Iris data and report the final test accuracy.

Frequently Asked Questions about vqc

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I train a variational quantum classifier on the Iris dataset?▼

Data re-uploading encodes 4 features onto 4 qubits per layer, using trainable Ry rotations and a CNOT ladder to preserve input information and increase circuit depth for classification tasks.

How does the parameter shift rule work for quantum classification training?▼

The parameter shift rule provides exact gradient estimation for the quantum circuit, enabling gradient-based optimization with Adam to update trainable rotations during the classification training workflow.

Can I use this variational quantum classifier for tabular data beyond the Iris dataset?▼

This variational quantum classifier targets Iris-like datasets or small benchmarks with 4 features and 3 classes, supporting multi-layer architectures for demonstrations of training, evaluation, and circuit export.

What Python scientific stack do I need for quantum classification training?▼

Quantum classification training requires a Python scientific stack including Torch, NumPy, and scikit-learn for data handling and optimization, plus a quantum circuit backend to execute gates.

What are the limitations of using a 4-qubit variational quantum classifier for supervised classification?▼

A 4-qubit variational quantum classifier is limited to small benchmarks like the Iris dataset, as 4 qubits restrict scalability for large tabular datasets while focusing on circuit expressiveness and exact gradient estimation.