Update README.md

README.md

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 ---
 license: apache-2.0
 pipeline_tag: tabular-regression
----
+datasets:
+- Allanatrix/QST
+tags:
+- Physics
+---
+# NexaQST: Quantum State Tomography with Physics-Informed Neural Networks
+
+**NexaQST** is a Quantum State Tomography model built using a Physics-Informed Neural Network (PINN) trained on synthetic 2-qubit experiments. This model leverages quantum mechanical priors such as positivity, Hermiticity, and trace constraints to ensure physically plausible reconstructions of quantum states.
+
+---
+
+## Model Overview
+
+- **Task**: Reconstruct quantum states (density matrices) from tomographic measurement traces
+- **System**: Simulated 2-qubit experiments
+- **Architecture**: Physics-Informed Neural Network (PINN)
+- **Constraints Embedded**:
+  - Positivity
+  - Hermiticity
+  - Trace normalization (Tr(ρ) = 1)
+
+---
+
+## Dataset Generation
+
+- **Simulation Toolkit**: [`QuTiP`](https://qutip.org/)
+- **Process**:
+  1. Generated full 2-qubit tomography experiments via simulation
+  2. Extracted and structured measurement traces
+  3. Derived backward synthetic traces from known density matrices
+  4. Created supervised training pairs: `(trace → density matrix)`
+  5. Enforced physical constraints directly inside the model during training
+
+---
+
+## Model Input/Output
+
+- **Input**: Vector of tomographic measurement traces
+- **Output**: Reconstructed density matrix (complex-valued 4x4 for 2 qubits)
+
+---
+
+## Example Usage
+
+```python
+# Pseudocode for usage
+
+from model import NexaQSTModel
+import torch
+
+model = NexaQSTModel()
+model.load_state_dict(torch.load("nexaqst_model.pt"))
+model.eval()
+
+traces = load_measurement_vector("qst_trace.npy")  # shape: (N,)
+rho_pred = model.predict_density_matrix(traces)
+
+# rho_pred is a 4x4 complex-valued matrix satisfying physical constraints
+````
+
+---
+
+## Applications
+
+* Quantum error correction diagnostics
+* Quantum system identification
+* Educational simulation of QST techniques
+* Physically consistent state estimation for quantum simulations
+
+---
+
+## Licensing & Citation
+
+* If used in publications or products, please credit the Nexa Scientific Suite.
+
+---
+
+## 🌐 Related Tools
+
+* [📁 Nexa Data Studio](https://huggingface.co/spaces/Allanatrix/NexaDataStudio)
+* [🔬 Nexa R\&D Hub](https://huggingface.co/spaces/Allanatrix/NexaR&D)
+* [🧠 Nexa MOE Models](https://huggingface.co/collections/Allanatrix/nexa-models)
+* [🌐 Nexa Hub (Main Portal)](https://huggingface.co/spaces/Allanatrix/NexaHub)
+
+---
+
+*Created by [Allan](https://huggingface.co/Allanatrix), independent quantum systems architect and ML researcher. Part of the Nexa scientific computing ecosystem.*