Proposing a Quantum simulator for integer factorization

Many cryptographic algorithms depend on computational complexity assumptions. Notorious cases are the RSA algorithm for public key criptography or the Diffie-Hellman key exchange protocol, to publicly agree on a common secret key. Both algorithms are known to be broken by quantum computing as well as those that can be reduced to a discrete logarithm problem. These are key algorithms in our digital society and are at the basis of everyday tasks, specially those that rely on digital signatures. The RSA algorithm, in particular, is probably the most used algorithm and is its assumed security the one that guards most of the e-commerce nowadays. In this case, it is the time complexity of finding the prime factors of a large number, that grows worse than polinomially with the size of the number, the main guardian of our cyberinfrastructure. The fact that a quantum computer can solve this problem in polynomial time using Shor's algorithm is seen as a potentially major disruption and has prompted security agencies to advice the progressive deprecation of these algorithms

A novel concept of entanglement distribution in optical n Networks

A major road-block in bringing QKD to the market is the missing scalability of a single QKD-link connecting two users to a use-case with many users in the same metropolitan area network (MAN). The typical trusted node concept used for this, beyond requiring the trust on all intermediate nodes, is not able to distribute entanglement without the help of quantum manipulations that have yet to be demonstrated. Here we extend the concept of entanglement to many pairs of users by the introduction of novel structures. The goal of this work is the design of a MAN for quantum and co-propagating classical signals to allow an arbitrarily high number of users not bounded by e.g. the number of CWDM or DWDM channels in the ITU grid. The number of coexistent multiplexed links is clearly limited by this usable fibre bandwidth, but the network must be able to select the corresponding user out of a large pool of possible communication partners (as in mobile phone networks)

Fluctuaciones en la métrica espacio temporal y mecánica cuántica

Tesis doctoral inédita leida en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Física Teórica. Fecha de lectura: 20-5-9

Proposing a Quantum simulator for integer factorization

Many cryptographic algorithms depend on computational complexity assumptions. Notorious cases are the RSA algorithm for public key criptography or the Diffie-Hellman key exchange protocol, to publicly agree on a common secret key. Both algorithms are known to be broken by quantum computing as well as those that can be reduced to a discrete logarithm problem. These are key algorithms in our digital society and are at the basis of everyday tasks, specially those that rely on digital signatures. The RSA algorithm, in particular, is probably the most used algorithm and is its assumed security the one that guards most of the e-commerce nowadays. In this case, it is the time complexity of finding the prime factors of a large number, that grows worse than polinomially with the size of the number, the main guardian of our cyberinfrastructure. The fact that a quantum computer can solve this problem in polynomial time using Shor's algorithm is seen as a potentially major disruption and has prompted security agencies to advice the progressive deprecation of these algorithms

Der Verstaedterungsprozess in den Niederlanden nach 1950 raumordnungspolitische Implikationen

TUB Berlin(83)-8R.5166.24 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman