Basic idea: We have studied the notion of entanglement shared between two parties, when one of them is non-inertial (which, locally, is equivalent to the presence of the gravitational force). It has been found that the entanglement is not an observer-independent quantity and crucially depends on the motion of the reference frame.
Reference: D. E. Bruschi, J. Louko, E. Martin-Martinez, A. Dragan, and I. Fuentes, The Unruh effect in quantum information beyond the single-mode approximation, Phys. Rev. A 82, 042332 (2010).
Basic idea: We show that a single point-like quantum particle can be used to determine absolute acceleration of its reference frame by local measurements on a quantum field. We find that this is only possible by measurements on highly excited massive fields, which reveals a special role played by the field mass in (general) relativity.
Reference: A. Dragan, I. Fuentes, and J. Louko, Quantum accelerometer: distinguishing inertial Bob from his accelerated twin Rob by a local measurement, Phys. Rev. D 83, 085020 (2011).
Basic idea: We study entanglement swapping between the vacuum state and a pair of accelerated point-like particles in an analytical, non-perturbative model of single-mode interaction.
References: A. Dragan, J. Doukas, E. Martin-Martinez, and D. Bruschi, Localised projective measurement of a relativistic quantum field in non-inertial frames, arXiv:1203.0655 (2012); A. Dragan, I. Fuentes, Probing the structure of vacuum entanglement, arXiv:1105.1192v1 (2011).
Basic idea: With the use of a toy-model of evaporating black hole we show that the energy contribution to the radiated flux of Hawking particles must originate from the region of spacetime outside the never-to-be-formed event horizon. Therefore it is pointless to argue about the loss of information without taking into account the back-reaction between the radiation and the collapsing matter.
Reference: A. Dragan, Debunking the black hole information paradox, arXiv:1003.0094 (2010).
Basic idea: Interference effects of states with no superpositions of particle numbers (Fock states) lead to practically indistinguishable consequences from the result of interference of superposed coherent states. This leads to the question, is it possible to verify the (in)validity of super-selection rules for massive particles at all?
Reference: A. Dragan and P. Zin, Interference of Fock states in a single measurement, Phys. Rev. A 76, 042124 (2007).
Basic idea: We show that the Principle of Relativity involving all, not only subluminal, inertial frames leads to the disturbance of causal laws in a way known from the fundamental postulates of Quantum Theory. We show how quantum indeterminacy based on complex probability amplitudes with superposition principle emerges from Special Relativity.
Reference: A. Dragan, Why devil plays dice?, arXiv:0806.4875 (2008).