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QOCTS - Quantum Optimal Control and Tracking Server

QOCTS is a comprehensive framework for designing, simulating, and executing pulse sequences on NV center quantum systems. It provides a modern web interface for pulse sequence editing, real-time simulation via QUSIM, and future integration with quantum hardware.

Vision

QOCTS aims to be a complete workflow solution for quantum control experiments:

1. Design - Visual pulse sequence editor with drag-and-drop interface
2. Simulate - Real-time quantum dynamics via QUSIM backend
3. Optimize - Optimal control algorithms (GRAPE, CRAB, Krotov) [planned]
4. Execute - Send sequences to real quantum hardware [planned]
5. Analyze - Photon counting statistics and data visualization

Features

Current (v0.1.0)

• Web-based Pulse Editor: Visual timeline for laser/MW/readout pulses
• Preset Sequences: Ramsey, Hahn Echo, CPMG, XY4, XY8, T1 measurement
• Time-dependent Simulation: Full Lindblad dynamics with QUSIM
• Photon Counting: Realistic detection with efficiency, dark counts, dead time
• Job Queue System: Background processing with history tracking
• Data Analysis: Range selection, statistics, export capabilities

Planned

• Optimal control integration (GRAPE, CRAB)
• Hardware backends (Qudi, custom AWG)
• Multi-qubit sequences
• Pulse calibration workflows
• Cloud deployment

Architecture

QOCTS/
├── server/                 # FastAPI backend
│   ├── models.py           # Pydantic models
│   ├── routes.py           # API endpoints
│   ├── queue.py            # Job queue management
│   └── worker.py           # Simulation worker (QUSIM integration)
├── web/                    # Next.js frontend
│   ├── src/
│   │   ├── app/            # Pages
│   │   ├── components/     # React components
│   │   │   ├── pulse-sequence-editor.tsx
│   │   │   ├── results-display.tsx
│   │   │   ├── job-history.tsx
│   │   │   └── system-settings.tsx
│   │   └── lib/            # API client
│   └── package.json
├── qocts_sim/              # QUSIM adapter
│   ├── interfaces/         # Simulator interface
│   └── adapters/           # Backend adapters
└── docs/                   # Documentation

Quick Start

Prerequisites

• Python 3.9+
• Node.js 18+
• QUSIM (for simulation backend)

Installation

# Clone repository
git clone https://github.com/xleonplayz/QOCTS.git
cd QOCTS

# Install server dependencies
pip install -e .

# Install frontend dependencies
cd web
npm install

Running

# Terminal 1: Start backend server
cd QOCTS/server
python -m server

# Terminal 2: Start frontend
cd QOCTS/web
npm run dev

Open http://localhost:3000 in your browser.

API Overview

Endpoint	Method	Description
/status	GET	Server status and queue info
/jobs	POST	Create new simulation job
/jobs/{id}	GET	Get job status
/jobs/{id}/result	GET	Get job result
/history	GET	List job history
/history/export	GET	Export history (JSON/CSV)

Pulse Sequence Format

{
    "laser_pulses": [
        {"start": 0, "duration": 300e-9, "power": 1.0}
    ],
    "mw_pulses": [
        {"start": 400e-9, "duration": 25e-9, "omega": 10, "phase": 0, "detuning": 0}
    ],
    "readout_start": 500e-9,
    "readout_duration": 300e-9
}

Integration with QUSIM

QOCTS uses QUSIM as its simulation backend. The qocts_sim module provides an adapter that:

• Translates pulse sequences to QUSIM Hamiltonians
• Creates time-dependent envelopes for MW and laser pulses
• Handles photon counting with realistic noise models
• Manages the Lindblad master equation solver

from qocts_sim import create_simulator

sim = create_simulator()
H = sim.create_hamiltonian()
H.add_term(sim.zfs_term(D=2.87))
H.add_term(sim.mw_drive_term(omega=envelope_function))
# ... execute simulation

Contributing

Contributions are welcome! Please feel free to submit issues and pull requests.

Related Projects

• QUSIM - Quantum Simulator for NV Centers

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_{Developed at Modular Supercomputing and Quantum Computing (MSQC)
Faculty 12, Computer Science and Mathematics
Goethe University Frankfurt, Campus Bockenheim}

Author: Leon Kaiser
l.kaiser@em.uni-frankfurt.de

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_{Licensed under the MIT License - free to use, modify, and distribute with attribution.}