Quantum Sentinel

Quantum Sentinel detects intruders using light interference. No cameras, no facial recognition. We sense disturbances without collecting identity data. Security without surveillance.

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Inspiration

Modern security systems rely on cameras, microphones, motion sensors, and massive data collection. In order to stay safe, we often must sacrifice our privacy.

Quantum information allows us to ask the question: Can we detect the presence of an intruder without identifying them?

Quantum mechanics says yes.

The Elitzur-Vaidman interaction-free measurement shows that a system can detect an object without interacting with it.

That idea sparked the creation of Quantum Sentinel: a privacy-first, tamper-evident security system powered by quantum interference rather than surveillance.

What it does

Quantum Sentinel uses a simulated Mach-Zehnder interferometer to sense whether a path in a room has been disturbed.

If the path is clear → perfect interference → detector reads 0.
If an intruder disturbs the path → interference flips → detector reads 1.

By scanning each row and column of a 2D room grid, the system:

  • detects when someone enters the room
  • identifies the intruder's location
  • never records identity, images, or biometric data
  • can even detect tampering via increased error rates

It's inspired by quantum radar and interaction-free measurement, but applied to ethical, privacy-preserving security.

How we built it

We constructed the core sensing mechanism using Qiskit primitives and Aer simulators:

  1. Implemented a Mach–Zehnder-style quantum circuit:
    • |0⟩ → H → P(φ) → H → measure
  2. Verified interference fringes through probability sweeps of φ ∈ [0, 2π]
  3. Modeled an "intruder" by flipping the phase φ = π, which reverses the interference outcome
  4. Mapped this sensor onto a Battleship-style grid, probing each cell for disturbances
  5. Extended it into a "room" where each row and column acts as a quantum beam
  6. Built visualizations showing:
    • Room grid
    • Row/column signals
    • Intruder reconstruction
    • Tamper-evident behavior based on noisy phases

Everything runs end-to-end in a Jupyter notebook for transparency and simplicity.

Challenges we ran into

  • Simulating decoherence: Modeling realistic which-path information is surprisingly tricky; early attempts made the intruder "invisible"
  • Designing intuitive visualizations: Translating quantum phase flips into understandable security readouts

Accomplishments that we're proud of

  • Implemented interaction-free disturbance detection using only 1 qubit
  • Demonstrated a form of tamper-evident detection using noisy-phase simulations
  • Built a complete system from quantum circuit to security application

What we learned

  • The power of quantum interference as a sensing tool
  • How phase, measurement, and superposition work inside real circuits
  • How to design structured, incremental systems: interferometer → Battleship → Sentinel → tamper-evident mode
  • That security doesn't have to conflict with privacy

What's next for Quantum Sentinel

  • Multi-intruder detection using entangled probes
  • Realistic noise modeling and decoherence
  • Hardware implementations on IBM Q devices
  • Large-grid scanning with optimized beam patterns
  • Integration with classical automation (smart home / secure facility prototypes)
  • Research-style paper expanding on quantum sensing and privacy-preserving detection

Ultimately, we hope Quantum Sentinel inspires more systems that make us safer without watching us.

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