Carles Roch i Carceller

Quantum Random Number Generators (QRNGs) are essential components for modern cryptography, as they are a practical source of true randomness, without which the security of such protocols cannot be guaranteed. Among the proposed schemes, Semi-Device-Independent QRNGs (SDI-QRNGs) based on photon-number constraints offer an appealing balance of security, speed, and experimental simplicity, but demonstrations have so far focused mainly on binary encoding and conditional min‑entropy certification. In this work, we report the first experimental implementation of a Continuous‑Variable SDI‑QRNG in a prepare‑and‑measure configuration building on the SDP‑based (Semi-Definite Programming) framework of Ref.~\cite{carceller2025}. This approach allows us to directly lower‑bound the conditional Shannon entropy, employ more complex modulation formats, and apply entropy‑accumulation techniques beyond the i.i.d. assumption. The experiment combines a low-loss integrated photonic heterodyne receiver with a simple transmitter built from commercial components, generating coherent‑state Quadrature-Phase-Shift-Keying (QPSK) modulation, to preserve experimental practicality while enabling high‑speed operation.