The dawn of quantum technology unveils a plethora of new possibilities and challenges in the world of information technology, one of which is the quest for secure information transmission. A breakthrough in classical algorithm or the development of a quantum computer could threaten the security of messages encoded using public key cryptosystems based on one-way function such as RSA. Quantum key distribution (QKD) offers an unconditionally secure alternative to such schemes, even in the advent of a quantum computer, as it does not rely on mathematical or technological assumptions, but rather on the universality of the laws of quantum mechanics. Physical concepts associated with quantum mechanics, like the uncertainty principle or entanglement, paved the way to the first successful security proof for QKD. Ever since, further development in security proofs for QKD has been remarkable. But the connection between entanglement distillation and the uncertainty principle has remained hidden under a pile of mathematical burden. Our main goal is to dig the physics out of the new advances in security proofs for QKD. By introducing an alternative definition of private state, which elaborates the ideas of Mayers and Koashi, we explain how the security of all QKD protocols follows from an entropic uncertainty principle. We show explicitly how privacy amplification protocol can be reduced to a private state distillation protocol constructed from our observations about the uncertainty principle. We also derive a generic security proof for one-way permutation-invariant QKD protocols. Considering collective attack, we achieve the same secret key generation rate as the Devetak-Winter's bound. Generalizing an observation from Kraus, Branciard and Renner, we have provided an improved version of the secret key generation rates by considering a different symmetrization. In certain situations, we argue that Azuma's inequality can simplify the security proof considerably, and we explain the implication, on the security level, of reducing a QKD protocol to an entanglement or a more general private state distillation protocol. In a different direction, we introduce a QKD protocol with multiple-photon encoding that can be implemented without a shared reference frame. We prove the unconditional security of this protocol, and discuss some features of the efficiency of multiple-photon QKD schemes in general.

The dawn of quantum technology unveils a plethora of new possibilities and challenges in the world of information technology, one of which is the quest for secure information transmission. A breakthrough in classical algorithm or the development of a quantum computer could threaten the security of messages encoded using public key cryptosystems based on one-way function such as RSA. Quantum key distribution (QKD) offers an unconditionally secure alternative to such schemes, even in the advent of a quantum computer, as it does not rely on mathematical or technological assumptions, but rather on the universality of the laws of quantum mechanics. Physical concepts associated with quantum mechanics, like the uncertainty principle or entanglement, paved the way to the first successful security proof for QKD. Ever since, further development in security proofs for QKD has been remarkable. But the connection between entanglement distillation and the uncertainty principle has remained hidden under a pile of mathematical burden. Our main goal is to dig the physics out of the new advances in security proofs for QKD. By introducing an alternative definition of private state, which elaborates the ideas of Mayers and Koashi, we explain how the security of all QKD protocols follows from an entropic uncertainty principle. We show explicitly how privacy amplification protocol can be reduced to a private state distillation protocol constructed from our observations about the uncertainty principle. We also derive a generic security proof for one-way permutation-invariant QKD protocols. Considering collective attack, we achieve the same secret key generation rate as the Devetak-Winter's bound. Generalizing an observation from Kraus, Branciard and Renner, we have provided an improved version of the secret key generation rates by considering a different symmetrization. In certain situations, we argue that Azuma's inequality can simplify the security proof considerably, and we explain the implication, on the security level, of reducing a QKD protocol to an entanglement or a more general private state distillation protocol. In a different direction, we introduce a QKD protocol with multiple-photon encoding that can be implemented without a shared reference frame. We prove the unconditional security of this protocol, and discuss some features of the efficiency of multiple-photon QKD schemes in general.

La Révolution de 1979 a provoqué en Iran une vague de méfiance à l’égard des autres pays et l’hostilité envers les États-Unis a mis le pays dans une position conflictuelle avec le monde occidental. Avec l’affaire de la prise d’otages en novembre 1979, les relations entre l’Iran, les États-Unis et l’Europe ont été coupées. Tout cela n’a pas été sans conséquences sur la conservation du patrimoine culturel : si Persépolis a échappé à la destruction, en revanche le mausolée de Reza Shah a été complétement détruit par les révolutionnaires. Cependant des démarches effectuées par les spécialistes eurent pour résultat l’enregistrement pour la première fois de trois monuments historiques de l’Iran sur la liste du patrimoine mondial : Tchogha Zanbil près de Suse, Persépolis dans la province de Fars et la place de Naghsh-e-Jahan à Ispahan. Malheureusement, le déclenchement subit de la guerre avec l’Irak n’a pas laissé le temps de mettre en place les mesures de protection et pendant huit ans les sites et les monuments historiques de l’Iran ont subi quantité de dégâts.Après la guerre, jusqu’en 1997, le gouvernement de M. Rafsandjani entreprit de relever les ruines résultant de « la Guerre Imposée ». Mais l’inflation, qui pourtant ne fut à aucun moment supérieure à ce qu’elle avait été pendant « l’époque de la Construction », entraîna peu à peu la dépréciation de la monnaie et l’augmentation des inégalités sociales. Cette situation, qui empira jusqu’au gouvernement de M. Rohani, fit qu’on porta moins d’attention au patrimoine culturel. En fait, après la Révolution de 1979, les biens du patrimoine culturel de l’Iran ont été répartis en deux groupes : ceux qui pouvaient être considérés comme le patrimoine religieux, et ceux qui, antérieurs à la conquête musulmane de la Perse, n’avaient aucun rapport avec la spiritualité musulmane chiite. Les investissements pour la restauration et la protection des monuments du premier groupe n’ont été faits que pour propager le chiisme et dans le but d’influencer de plus en plus l’opinion publique, déjà sensible à la question de la religion et aux miracles des imams chiites. Cependant, bien qu’appartenant à ce groupe, certaines mosquées historiques et des caravansérails n’intéressent pas les organismes culturels du pays, du fait de leur faible rentabilité. En soi, la meilleure solution pour réaliser les plans de sauvegarde des monuments historiques serait la participation de la population, mais l’étude du lien entre la société et le gouvernement montre qu’une telle coopération dépasse largement le seul domaine culturel et prend aujourd’hui en Iran un sens politique. / The Revolution of 1979 in Iran leaded to a wave of distrust of the other lands and to hostility towards the United States. It put the land also into a situation of confrontation with western world. The hostage-taking in November 1979 resulted in a breakup of relations between Iran, the United States and Europe. All of this has not been without effect on the heritage conversations.If Persepolis escaped the destruction, but Reza Shah’s Mausoleum was completely demolished by revolutionists. However the employment of specialists had an outcome, that for the first time three historical monuments of Iran were put on the list of UNESCO-world heritage site: Tchogha Zanbil near Susa, Persepolis in Fars-province and Naghsh-e Jahan Square (world-image) in Esfahan. Unfortunately the sudden outbreak of war with Iraq allowed no time for protection-sanction and for 8 years the historical cities and monuments of Iran have been much more damaged.After the war, the government of Akbar Rafsanjani committed to rebuild the ruins resulted by imposed war. But never higher as “period of construction”, the inflation leaded gradually to a currency debasement, also to an increase in social inequality. Got worse till 11. government, this situation made the people pay less attention to cultural heritage.After the revolution of 1979, the cultural goods of Iran were separated into two groups, on the one hand, the ones regarded as religious heritage and on the other hand, the ones built before the Muslims’ conquest with no deal with shiitic spirituality. The investment for protection of monuments in the first group aimed to dissemination of Shiism thus the public opinion, which has already been sensitive to the religion issues and the miracle of shiitic imams, should be influenced. But a few historical mosques and caravansaries belonged to this group, due to its low profitability didn’t interest the culture-organization.The best solution to ensure the preservation of historical monuments should be the involvement of population. However the investigations of the relation between society and government showed, that such a cooperation goes far beyond the cultural field and has a political meaning in society.