arXiv subjects

J. L. Montenegro Ferreira

Publications and source records attributed to J. L. Montenegro Ferreira.

4 recordsLinked to original sources

arXiv2026

Time-Rescaled STIRAP Enables Compact Cascaded Frequency Conversion

In this letter we explore how full frequency conversion can be performed in shorter optical devices by using a STIRAP-like protocol modified by the time rescaling shortcut to adiabaticity. We first show a detailed, step-by-step process of how the coupled equations for two simultaneous three-wave mixing processes can be written in terms of a STIRAP-like system. From the properties of the STIRAP protocol, we know that the ensuing process will result in robust conversion, but require long propagation distances inside the bulk crystal or waveguide. We then apply the time rescaling shortcut to adiabaticty in the conversion process to create a TR-STIRAP protocol, showing that full and robust conversion is also obtained, but at a fraction of the propagation distance. We also show how the original shaping of the coupling coefficients required by the TR-STIRAP can be approximated by Gaussian functions with high conversion fidelity, thus simplifying the experimental implementation. Finally, a possible application of the new protocol is discussed in the context of single-photon detection in the MIR.

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arXiv2024

Shortcuts to adiabaticity designed via time-rescaling follow the same transitionless route

Time-rescaling (TR) has been recently proposed as a method to engineer fast processes, also known as shortcuts to adiabaticity (STA), which enables the coherent control of quantum systems beyond the adiabatic regime [B. L. Bernardo, Phys. Rev. Res. 2, 013133 (2020)]. The method provides the Hamiltonians that generate the fast processes without requiring information about the instantaneous eigenstates of a reference protocol, whereas experimental implementations dismiss additional coupling fields when compared with adiabatic protocols. Here, we revisit the technique and show that the obtained fast dynamics are transitionless, similar to the ones designed via the famous counterdiabatic (CD) approach. We also show that the time evolution of the STA found via TR relates to that of the reference adiabatic protocol by a simple reparametrization of time. To illustrate our findings, we studied the problem of speeding up the stimulated Raman adiabatic passage (STIRAP) and found out that TR revealed quantum dynamics more robust to parameter variations than those provided by the CD technique. Our results shed new light on the application of TR in the control of larger quantum systems.

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arXiv2024

Quantum state tomography of photon's polarization and path degrees of freedom

Quantum state tomography (QST), the process through which the density matrix of a quantum system is characterized from measurements of specific observables, is a fundamental pillar in the fields of quantum information and computation. In this work, we propose a simple QST method to reconstruct the density matrix of two qubits encoded in the polarization and path degrees of freedom of a single photon, which can be realized with a single linear-optical setup. We demonstrate that the density matrix can be fully described in terms of the Stokes parameters related to the two possibles paths of the photon, together with a quantum version of the two-point Stokes parameters introduced here. Our findings put forward photonic circuits for the investigation of the dynamics of open quantum systems.

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arXiv2022

Influence of polarization and the environment on wave-particle duality

Wave-particle duality is certainly one of the most curious concepts of contemporary physics, which ascribes mutually exclusive behaviors to quantum systems that cannot be observed simultaneously. In the context of two-path interferometers, these two behaviors are usually described in terms of the visibility of interference fringes and the path distinguishability. Here, we use quantum information-theoretic tools to derive quantifiers of these two properties, which account for the combined influence of path probability and polarization, and demonstrate that they satisfy a complementarity relation. We further show that the derived quantities can work as probes in the study of open quantum dynamics by revealing interesting facets of environment actions, such as: decoherence, depolarization and scattering.

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