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Seminar - Quantum simulation with integrated photonics


on 21-11-2014

... Fabio Sciarrino, Università di Roma La Sapienza

21/11/2014, 14:00
Room P9, Mathematics Building, IST


Integrated photonics circuits have a strong potential to perform quantum information processing. Indeed, the ability to manipulate quantum states of light by integrated devices may open new perspectives both for fundamental tests of quantum mechanics and for novel technological applications. Within this framework we have developed a directional coupler, fabricated by femtosecond laser waveguide writing, acting as an integrated beam splitter able to support polarization-encoded qubits. As following step we addressed the implementation of quantum walk. This represents one of the most promising resources for the simulation of physical quantum systems, and has also emerged as an alternative to the standard circuit model for quantum computing. Up to now the experimental implementations have been restricted to single particle quantum walk, while very recently the quantum walks of two identical phot ons have been reported. For the first time, we investigated how the particle statistics, either bosonic or fermionic, influences a two-particle discrete quantum walk. Such experiment has been realized by adopting two-photon entangled states and integrated photonic circuits. As following step we have exploited this technology to simulate the evolution for disordered quantum systems observing how the particle statistics influences Anderson localization. Finally we will discuss the perspectives of optical quantum simulation: the implementation of the boson sampling to demonstrate the computational capability of quantum systems and the development of integrated architecture with three-dimensional geometries.



Quantum Computation and Information Seminar
http://math.tecnico.ulisboa.pt/seminars/qci/?action=next

Support: Phys-Info (IT), SQIG (IT), CFIF and CAMGSD, with support from FCT, FEDER and EU FP7, namely via the Doctoral Programme in the Physics and Mathematics of Information (DP-PMI), and projects PEst-OE/EEI/LA0008/2013, QuSim, CQVibes, Landauer (318287) and PAPETS (323901). More Information..

Seminar - Quantum measurement and feedback with atoms and cavities


on 14-11-2014

... Jean-Michel Raimond, École Normale Supérieure

14/11/2014, 14:00
Room P9, Mathematics Building, IST


Quantum non-demolition information on the number of microwave photons stored in a superconducting cavity can be obtained by sending trough the mode circular Rydberg atoms, interacting dispersively with the field. This information can be used to reveal the quantum jumps of light. We will describe an optimal use of this information, based on the past quantum state formalism. Photon number measurement can also be used to stabilize a non-classical photon number state against decoherence, in a quantum feedback process operating in the steady state. Finally, the principle of quantum feedback can be applied to an improved adaptive QND measurement of the photon number. We shall report on these recent experiments and on the perspectives they open for non-classical state manipulations.



Quantum Computation and Information Seminar
http://math.tecnico.ulisboa.pt/seminars/qci/?action=next

Support: Phys-Info (IT), SQIG (IT), CFIF and CAMGSD, with support from FCT, FEDER and EU FP7, namely via the Doctoral Programme in the Physics and Mathematics of Information (DP-PMI), and projects PEst-OE/EEI/LA0008/2013, CQVibes, Landauer (318287) and PAPETS (323901). More Information..