NCTS (South)



PLACER49223, Second Physics Building , NCKU

FIELDQuantum Information Science

SPEAKER Dr. Ravishankar Ramanathan - University Libre de Bruxelles, Belgium

TITLERandomness Amplification and Relativistic Causality

ABSTRACTThe application of Quantum Non-Local correlations, certified by the violation of Bell inequalities, to so-called Device-Independent Cryptographic tasks has gathered much interest in the Quantum Information community recently. In this talk, I will present a protocol for the fundamental cryptographic task of Randomness Amplification, i.e., obtaining perfectly random bits starting from a weakly random source, using quantum non-local correlations exhibiting so-called Hardy paradoxes. The protocol is shown to satisfy the strong composability security criterion, and is secure against adversaries obeying the No-Signaling conditions. In the second part of the talk, I will focus on the derivation of the No-Signaling conditions from Einsteinian Relativistic Causality. We show that when more than two parties participate in a Bell experiment, the no-signaling conditions are sufficient but not necessary to respect causality. We examine consequences of this observation, to many-party non-locality and device-independent cryptography against eavesdroppers only constrained by the laws of relativity.