arXiv subjects

J. G. G. de Oliveira Jr.

Publications and source records attributed to J. G. G. de Oliveira Jr..

5 recordsLinked to original sources

arXiv2026

The Thermodynamic Geometry of Conditional Control

Information is widely regarded as the resource underlying the thermodynamic advantages enabled by conditional control. We show, however, that informational quantities such as Holevo information and accessible distinguishability, although constraining the achievable advantage, do not uniquely determine its thermodynamic value. The missing ingredient is a passive spectral rearrangement vector that characterizes the effect of conditioning on the ensemble. Specifically, the conditional-control advantage is exactly determined by the geometric pairing between this vector and the Hamiltonian energy-gap structure. This result reveals a thermodynamic geometry of conditional control, explains how informationally equivalent ensembles can possess different thermodynamic values, and identifies the passive spectral rearrangement vector as the minimal operational descriptor required to determine the thermodynamic value of conditional control for a fixed Hamiltonian.

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arXiv2019

Jarzynski equality for superconducting optical cavities: an alternative path to determine Helmholtz free energy

A superconducting cavity model was proposed as a way to experimentally investigate the work performed in a quantum system. We found a simple mathematical relationship between the free energy variation and visibility measurement in quantum cavity context. If we consider the difference of Hamiltonian at time $t_0$ and $t_λ$ (protocol time) as a quantum work, then the Jarzynski equality is valid and the visibility can be used to determine the work done on the cavity.

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arXiv2017

Two proposals to protect a qubit using CQED techniques: inequality between atomic velocity dispersion and losses of a quantum memory

We present in this work an analysis of the damage imposed by the atom on the field state inside a lossy superconducting cavity. To access such effects, we propose two procedures to preserve a qubit of the decay effects of an imperfect quantum memory: the first by means of an quasi-instantaneous phase kick applied in the atom, and the second by means of controlled resonant and dispersive interactions. We immediately demonstrate that, in both procedures, the dwell time of the qubit in the cavity increases significantly, being expressively higher for the second. A relation between the inaccuracy of the preparation of the atomic beam and the quality of the cavity arises naturally from our calculations for each procedure. This result is unprecedented, and sets out the rules to increase the dwell time of the qubit.

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arXiv2017

Exotic looped trajectories via quantum marking

We provide an analytical and theoretical study of exotic looped trajectories (ELTs) in a double-slit interferometer with quantum marking. We use an excited Rydberg-like atom and which-way detectors such as superconducting cavities, just as in the Scully-Englert-Walther interferometer. We indicate appropriate conditions on the atomic beam or superconducting cavities so that we determine an interference pattern and fringe visibility exclusive from the ELTs. We quantitatively describe our results for Rubidium atoms and propose this framework as an alternative scheme to the double-slit experiment modified to interfere only these exotic trajectories.

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arXiv2016

An open quantum system approach to complementarity in neutral kaon interferometry

In bipartite quantum systems, entanglement correlations between the parties exerts direct influence in the phenomenon of wave-particle duality. This effect has been quantitatively analyzed in the context of two qubits by M. Jakob and J. Bergou [Optics Communications 283(5) (2010) 827]. Employing a description of the $K$-meson propagation in free space where its weak decay states are included as a second party, we study here this effect in the kaon-antikaon oscillations. We show that a new quantitative "triality" relation holds, similar to the one considered by Jakob and Bergou. In our case, it relates the distinguishability between the decay products states corresponding to the distinct kaon propagation modes $K_S $, $K_L $, the amount of wave-like path interference between these states, and the amount of entanglement given by the reduced von Neumann entropy. The inequality can account for the complementarity between strangeness oscillations and lifetime information previously considered in the literature, therefore allowing one to see how it is affected by entanglement correlations. As we will discuss, it allows one to visualize clearly through the $K^{0}$$\overline{K}\,^{0}$ oscillations the fundamental role of entanglement in quantum complementarity.

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