---
license: apache-2.0
language:
  - en
library_name: transformers
tags:
  - quantum
  - confidence-estimation
  - uncertainty
  - pennylane
  - gpt-oss
  - hallucination-detection
pipeline_tag: text-classification
---

<div align="center">

# Q-GPT

![qgpt](https://cdn-uploads.huggingface.co/production/uploads/67329d3f69fded92d56ab41a/91QMIE7cP4V8xZHvS_cTA.jpeg)

### Quantum-Enhanced Confidence Estimation for Language Models

[![PennyLane](https://img.shields.io/badge/PennyLane-Quantum_ML-6C3483?style=for-the-badge)](https://pennylane.ai/)
[![PyTorch](https://img.shields.io/badge/PyTorch-Compatible-EE4C2C?style=for-the-badge&logo=pytorch)](https://pytorch.org/)
[![License](https://img.shields.io/badge/License-Apache_2.0-green?style=for-the-badge)](https://www.apache.org/licenses/LICENSE-2.0)

**Know when your LLM is confident — and when it's guessing.**

</div>

---

## 🎯 What is Q-GPT?

Q-GPT is a **quantum neural network head** that attaches to any language model and estimates how confident the model is in its response. It helps you detect when the model might be "hallucinating" or making up information.

### The Problem

Large Language Models (LLMs) always produce fluent text — even when they don't know the answer. They sound confident even when they're wrong. This makes it hard to trust their outputs in critical applications.

### The Solution

Q-GPT analyzes the internal hidden states of the model using a **variational quantum circuit**. Quantum computing naturally captures complex patterns and uncertainties that classical networks might miss. The result: a confidence score that tells you whether to trust the response.

---

## 🧠 How It Works

```
┌─────────────────────────────────────────────────────────────────┐
│                        Q-GPT Architecture                        │
├─────────────────────────────────────────────────────────────────┤
│                                                                   │
│  LLM Hidden States                Quantum Circuit                 │
│  [2880 dimensions]                [4 qubits]                      │
│         │                              │                          │
│         ▼                              │                          │
│  ┌─────────────┐                       │                          │
│  │  Compress   │  ──────────────────►  │                          │
│  │  to 4 dims  │                       │                          │
│  └─────────────┘                       ▼                          │
│                               ┌─────────────────┐                 │
│                               │   RY   RZ       │                 │
│                               │   │    │        │  Layer 1        │
│                               │   Rot ─●─ CNOT  │                 │
│                               ├─────────────────┤                 │
│                               │   Rot ─●─ CNOT  │  Layer 2        │
│                               ├─────────────────┤                 │
│                               │   Rot ─●─ CNOT  │  Layer 3        │
│                               └─────────────────┘                 │
│                                        │                          │
│                                        ▼                          │
│                               ┌─────────────────┐                 │
│                               │  Measure ⟨Z⟩    │                 │
│                               │  on each qubit  │                 │
│                               └─────────────────┘                 │
│                                        │                          │
│                                        ▼                          │
│                               ┌─────────────────┐                 │
│                               │   Confidence    │                 │
│                               │   0.0 — 1.0     │                 │
│                               └─────────────────┘                 │
│                                                                   │
└─────────────────────────────────────────────────────────────────┘
```

### Step by Step:

1. **Extract Hidden States** — When the LLM generates a response, we capture its internal representation (hidden states from the last layer).

2. **Compress** — The high-dimensional hidden states (2880 dimensions for GPT-OSS) are compressed to 4 values using a small neural network.

3. **Quantum Encoding** — These 4 values are encoded into quantum states using rotation gates (RY, RZ). Each value controls the angle of rotation for one qubit.

4. **Variational Layers** — The qubits pass through multiple layers of:
   - **Rotation gates** (trainable parameters that learn patterns)
   - **CNOT gates** (create entanglement between qubits)
   
5. **Measurement** — We measure the expectation value ⟨Z⟩ of each qubit, giving us 4 numbers between -1 and +1.

6. **Confidence Output** — A final layer converts these measurements into a confidence score (0-1) and an uncertainty estimate.

### Why Quantum?

- **Entanglement** captures complex correlations in the data that classical networks struggle with
- **Superposition** allows exploring multiple states simultaneously
- **Inherent probabilistic nature** naturally represents uncertainty
- **Compact representation** — 4 qubits can represent 16-dimensional state space

---

## 📊 What You Get

| Output | Description |
|--------|-------------|
| `confidence` | Score from 0.0 to 1.0 — how sure the model is |
| `uncertainty` | Quantum-derived uncertainty measure |
| `should_refuse` | Boolean — True if confidence < 0.3 (model should decline to answer) |
| `confidence_label` | Human-readable: "very high", "high", "moderate", "low", "very low" |

---

## 💻 Usage

### Installation

```bash
pip install pennylane torch transformers
```

### Quick Start

```python
from quantum_head import load_qgpt

# Load model with quantum head
model, tokenizer = load_qgpt("squ11z1/gpt-oss-9b-reasoning")

# Prepare input
prompt = "What is the capital of France?"
inputs = tokenizer(prompt, return_tensors="pt").to(model.device)

# Generate with confidence
outputs = model.generate_with_confidence(
    inputs.input_ids,
    max_new_tokens=50
)

# Check results
print(f"Response: {tokenizer.decode(outputs['sequences'][0])}")
print(f"Confidence: {outputs['confidence_label']}")  # "high"
print(f"Should refuse: {outputs['should_refuse']}")  # False
```

### Using Just the Quantum Head

```python
from quantum_head import QuantumHead
import torch

# Create quantum head for your model's hidden size
head = QuantumHead(hidden_size=2880)

# Get hidden states from your model
# hidden_states shape: [batch_size, hidden_size]
hidden_states = torch.randn(1, 2880)

# Get confidence
output = head(hidden_states)
print(f"Confidence: {output['confidence'].item():.2%}")
```

---

## 🎓 Training the Quantum Head

The quantum head can be trained on examples where you know if the model was correct:

```python
from train import train_quantum_head

train_quantum_head(
    model_name="squ11z1/gpt-oss-9b-reasoning",
    train_data_path="train_data.jsonl",  # {text, confidence, is_correct}
    epochs=3,
)
```

Training data format (JSONL):
```json
{"text": "What is 2+2? The answer is 4.", "confidence": 0.95, "is_correct": true}
{"text": "The moon is made of cheese.", "confidence": 0.2, "is_correct": false}
```

---

## 📁 Files

| File | Description |
|------|-------------|
| `quantum_head.py` | Main implementation (QuantumHead, QGPT, load_qgpt) |
| `train.py` | Training script for the quantum head |
| `__init__.py` | Package initialization |

---

## 🔬 Technical Details

| Parameter | Value |
|-----------|-------|
| Qubits | 4 |
| Variational Layers | 3 |
| Trainable Parameters | ~2,000 (quantum) + ~200,000 (classical) |
| Framework | PennyLane + PyTorch |
| Fallback | Classical approximation if PennyLane unavailable |

---

## ⚠️ Limitations

- **Not perfect** — Confidence estimation is inherently uncertain
- **Training data dependent** — Quality depends on training examples
- **Simulation** — Currently runs on quantum simulator, not real hardware
- **Latency** — Adds ~10-50ms per inference (quantum circuit execution)

---

## 📖 Citation

```bibtex
@misc{qgpt2026,
  title={Q-GPT: Quantum-Enhanced Confidence Estimation for Language Models},
  author={squ11z1},
  year={2026},
  url={https://huggingface.co/squ11z1/Q-GPT}
}
```

---

## 🙏 Acknowledgments

- [PennyLane](https://pennylane.ai/) — Quantum ML framework
- [GPT-OSS](https://huggingface.co/squ11z1/gpt-oss-9b-reasoning) — Base model

---

<div align="center">

**Pro Mundi Vita**

</div>