Analysis and results of laboratory experiments for the 'Quantum Cryptography and Security' course (AY 2023/24).
This repository is organized into three folders, one for each experiment: Quantum Random Numbers Generation, Error Correction, and Quantum Key Distribution. Each folder has a functions.py file with the analysis, a folder with the graphs, and the final report.
The implementation of QRNG can be characterized by the degree of trust in the different elements of the protocol. The simplest case is the trusted setup, in which all the elements are supposed to be controlled and uncorrelated with the environment. We can relax this hypothesis and consider semi-Device-Independent setups with uncharacterized sources or measurements.
In this experiment, we use the phenomenon known as spontaneous parametric downconversion to generate a two-photon entangled state and characterize it in terms of polarization. The security analysis is based on the leftover hash lemma with bounds on the min-entropy based on either the state tomography or the entropic uncertainty principle.
To reconcile the keys, Alice and Bob need to cooperate over a classic public channel. In this report, we describe three different protocols: Cascade (based on parity comparison and iterative binary search), Winnow (based on parity comparison and syndrome decoding), and the LDPC codes (with rate modulation via puncturing and shortening).
We compare the performances in terms of two efficiency metrics based on the error correction capability and the Slepian-Wolf bound.
The standard QKD protocols are designed to work with true single-photons. However, such experimental setups are still unavailable for practical implementation, and weak coherent laser pulses (vulnerable to the so-called photon number splitting attack) are used instead.
In this report, we will introduce and analyze a 3-states 1-decoy QKD protocol, evaluating the security of the obtained keys in the finite scenario. Such methods provide robust protocols to overcome the limitations of the multi-photon events and the finite keys.
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