Quantum key distribution (QKD) provides a method to facilitate the exchange of a secret key that may be used for cryptographic purposes such as encryption. The security model of QKD is based on the laws of quantum mechanics. In principle, this ensures that any eavesdropping activity cannot stay undisclosed. In practice however, the theoretical model may not be properly implemented or it may fail to appropriately describe the actual implementation. Such theory-practice deviations lead to security loopholes that may be exploited by the eavesdropper to gain information about the secret key without being disclosed. In my doctoral project, I worked on experimentally discovering and analysing several loopholes and vulnerabilities on practical QKD systems (most notably, the commercially available research platform 'Clavis2' from ID Quantique). These include the risk of detector control attacks due to superlinear behavior of single-photon avalanche diodes, the weakness of the calibration routine of the system, and implementation and risk analysis of realistic Trojan-horse attacks. I also discussed measures to close the loopholes since the main objective of this work was to secure both existing and future QKD implementations.

My thesis work was on quantum-optical state engineering at the few-photon level. Engineering of quantum states refers to their generation, detection and characterization. The main focus of this experimental study was to engineer various quantum-optical states such as the single-photon Fock state, the squeezed-vacuum state and arbitrary coherent superpositions until the two-photon level. The states were produced by employing conditional state preparation on the output of a parametric down-conversion performed in a nonlinear medium and measured using homodyne tomography. The Wigner function and the density matrix that characterized several properties (such as the nonclassical attributes) of the prepared states were observed as well as verified using apposite theoretical models.

1. Optimizations in Variable Length Decoding method and adding Error Resilience for VC1 Decoder2. Porting VC1 Decoder on nVIDIA's propietary GoForce SDK (GFSDK) platform3. Integrating embedded HW accelerators and a DSP module to the GFSDK4. Enhancing H264 Decoder and writing a usecase for ISDB-T implementation on handheld devices

1. Dual Degree Project - Ultrafast pulse shaping and characterization for optical communication: Performance analysis of ultrafast pulse shaping techniques based on spatial light modulation to compensate the higher degrees of dispersion. 2. Electronics Design Project - Mobile Diagnostic System: Conceptualized and designed an 89C52 microcontroller-based system, as a prototype for a mobile medical services station. 3. Digital Signal Processing Project - Viterbi Implementation on a TMS320C5x DSP kit for V.32 Modems:Simulated the V.32 Standard by differential and convolutional encoding of 4 bits to 5 bits.