arXiv subjects

Lucas Lamata

Publications and source records attributed to Lucas Lamata.

60 records · Page 4Linked to original sources

arXiv2007

Developments in entanglement theory and applications to relevant physical systems

This Thesis is devoted to the analysis of entanglement in relevant physical systems. Entanglement is the conducting theme of this research, though I do not dedicate to a single topic, but consider a wide scope of physical situations. I have followed mainly three lines of research for this Thesis, with a series of different works each, which are, Entanglement and Relativistic Quantum Theory, Continuous-variable entanglement, and Multipartite entanglement.

quant-ph↗

arXiv2006

Spin entanglement loss by local correlation transfer to the momentum

We show the decrease of spin-spin entanglement between two s=1/2 fermions or two photons due to local transfer of correlations from the spin to the momentum degree of freedom of one of the two particles. We explicitly show how this phenomenon operates in the case where one of the two fermions (photons) passes through a local homogeneous magnetic field (optically-active medium), losing its spin correlations with the other particle.

quant-ph↗

arXiv2006

Generation of bipartite spin entanglement via spin-independent scattering

We consider the bipartite spin entanglement between two identical fermions generated in spin-independent scattering. We show how the spatial degrees of freedom act as ancillas for the creation of entanglement to a degree that depends on the scattering angle, $θ$. The number of Slater determinants generated in the process is greater than 1, corresponding to genuine quantum correlations between the identical fermions. The maximal entanglement attainable of 1 ebit is reached at $θ=π/2$. We also analyze a simple $θ$ dependent Bell's inequality, which is violated for $π/4<θ\leqπ/2$. This phenomenon is unrelated to the symmetrization postulate but does not appear for unequal particles.

quant-ph↗

arXiv2005

Dealing with entanglement of continuous variables: Schmidt decomposition with discrete sets of orthogonal functions

We propose a method for obtaining the Schmidt decomposition of bipartite systems with continuous variables. It approximates the modes to the prescribed accuracy by well known orthogonal functions. We give some criteria for the control of errors. We illustrate the method comparing its results with the already published analysis for entanglement of biphotons. The agreement is excellent.

quant-ph↗

arXiv2005

A time representation

The paper contains a proposal for an energy and time representation. We construct modes that correspond to fuzzy distributions around discrete values of energy or time. The modes form an orthogonal and complete set in the space of square integrable functions. Energy and time are self adjoint in the space spanned by the modes. The widths of the modes are analyzed as well as their energy-time uncertainty relations. The lower uncertainty attainable for the modes is shown. We also show times of arrival for massless particles.

quant-ph↗

arXiv2003

Time of arrival with resonances: Beyond scattering states

Assorted questions: Time as a parameter in Quantum Mechanics. No-Go theorems for a time operator. Localization, time and causality. Causality violation. Localization again. Lesson 1: Evading the troubles: Im E finite. Lights and shadows of a time operator:"Table-top Spacetime" quantum mechanics. Biphotons at Berkeley. Time operator build-up. Good news - bad news. Lesson 2: We need the resonances to tell one.

quant-ph↗