Acceptable noise level of quantum circuit for encrypting plaintext
Totok Sutojo, Supriadi Rustad, De Rosal Ignatius Moses Setiadi, Muhamad Akrom, Guruh Fajar Shidik, Hermawan Kresno Dipojono · Franklin Open · 2025
This study investigates quantum cryptography using quantum circuits for encrypting and decrypting plaintext data. Various quantum gates were combined to form encryption and decryption circuits, demonstrating the potential of quantum cryptography to provide a robust security mechanism compared to classical methods. The circuits were evaluated under five major types of quantum noise: depolarizing, amplitude damping, phase damping, Pauli, and reset noise. Results indicate that the circuits remain robust up to noise levels ranging from 0.35 to 0.5, depending on the circuit configuration. Specifically, circuits without Hadamard and rotation gates exhibited greater stability, while circuits incorporating these gates were more susceptible to noise due to induced superposition and entanglement. The permissible quantum state probability thresholds were also established for successful decryption. Furthermore, the proposed encryption method, which processes every two plaintext characters using 16 qubits, outperformed classical encryption schemes across several metrics, including chi-square, entropy, avalanche effect, adjacent bits, and run tests, demonstrating enhanced randomness and diffusion characteristics. These results highlight the potential of quantum circuits to achieve secure encryption with improved performance under practical noise conditions, addressing a critical challenge in quantum cryptography for near-term quantum devices.