Safety and Security

The didactics of quantum physics is an interesting field of research now that concepts such as quantum superposition and entanglement find their way into curricula and technology. For educational purposes we developed an analogy tool: electronic Quantum Dice. We will illustrate how the Quantum Dice can be used to visualize the role of superposition and entanglement in the field of quantum secure communication.

As digital systems expand, protecting against counterfeiting and ensuring secure authentication are becoming urgent. Physical unclonable functions (PUFs) address this need by harnessing fabrication variations to produce unique, irreproducible signatures. We present integrated photonic time-domain PUFs (tPUFs) built from silicon nitride ring resonator networks. Cascaded, nested, and spiral designs were fabricated and tested, revealing distinct spectral fingerprints across identically designed chips. Temporal stability measurements confirm that these responses are robust over time. Using peak-counting and compression metrics, we show that scaling the number of resonators increases spectral complexity and unpredictability. Our findings demonstrate that photonic tPUFs offer a scalable path toward secure hardware authentication, with future work targeting phase-sensitive readout and electro-optic modulation for enhanced security.

Quantum computers will be deployed primarily as cloud-based resources, requiring clients to offload computations to a remote server. To do so securely, clients must protect their input data and proprietary algorithms, motivating the need for secure delegated quantum computing (SDQC). We introduce the QEnclave, a hardware security module (HSM) that establishes a secure connection between the client and server. The QEnclave lets the client control input qubits and apply random state rotations, keeping the computation blind even to an untrusted server. This approach enables practical and secure access to quantum cloud services.

In defense, strong RF jammers are used to disrupt or damage communication systems, making high-resolution and frequency-agile filters essential to suppress interference without affecting the signal band. Microwave photonics offers a powerful solution, leveraging the broadband and tunable nature of photonics for RF signal processing. We present a compact silicon nitride based photonic integrated circuit (PIC) that combines a 500-µm disk resonator with surface acoustic wave (SAW) enhanced Brillouin scattering, achieving an ultra-high resolution 2.2-MHz bandwidth notch filter that is continuously tunable across a 10-GHz range.