## RELATIVISTIC AND QUANTUM INFORMATION

**Introduction.**I have mainly focused my research in the field of Relativistic Quantum Information (RQI). This wonderful and exciting field merges Relativity with Quantum Information (QI), aiming at understanding how QI tasks are affected when relativistic effects are taken into consideration. Pioneering work [1-3] began to address these issues and unexpected features were found.Although the first results were indeed groundbreaking, not much attention was drawn until the last 5-6 years, when more researchers focused their attention onto moving beyond purely quantum mechanical predictions.

**Core ideas in RQI.**The main idea that lies behind RQI is that relativistic effects should affect quantum information protocols and processing. Although it might seems specific to QI only, this idea can be extended even further. Relativity should affect anything that involves information. Standard predictions from Quantum Field Theory suggest that since the concept of particle is not observer independent, different observers will in general observe different amount of particles as content of a quantum state. For example, an inertial observer (i.e. moving with constant velocity) might say that a state contains no particles (the Minkowski vacuum). An accelerated observer will not agree. If he or she is uniformly accelerated, we call him or her Rindler observer, it is a standard result from Unruh ( see [4]) that this observer will perceive the Minkowski vacuum (which is empty as described by the inertial observer) as full of particles.

**Localized system for relativistic quantum information processing.**While the first results were obtained using global fields, which "live" on the entire spacetime, it has remained an open question how to address issues such as the influence of motion on entanglement when fields are confined, for example within cavities.

I have mainly contributed to this field by introducing and developing techniques to treat mode entanglement of modes within one or two cavities. I have shown, mainly together with my colleagues at Nottingham, that when one cavity moves, entanglement between the modes of a quantum field is affected and can be degraded, preserved or created. I have provided the techniques to fully characterized the phenomena that occurred in such localized systems. My results have attracted the interest of experimental scientists and we are now looking at possible experimental proposals.

A recent avenue that has been proposed by myself and collaborators investigates how to employ localized detectors, modeled by harmonic oscillators, for tasks that are typically investigated with Unruh-deWitt detectors. Unruh-deWitt detectors require perturbation theory which, a part from mathematical challenges, does not provide a full understanding on the physics under investigation. We have shown that, contrary to setups involving Unruh-deWitt, it is possible to employ this new scheme to analytically solve the time evolution of interacting quantum systems.

## References

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Roadmap of Quantum ICT Laboratory of National Institute of Information and Communications Technology of Japan: http://www.nict.go.jp/en/advanced\_ict/quantum/roadmap.html;

Quantum Information Science and Technology Roadmap of USA: http://qist.lanl.gov/qcomp\_map.shtml - "Quantum communication with an accelerated partner", T. G. Downes, T. C. Ralph and N. Walk, Phys. Rev. A 87, 012327 (2013)
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