arXiv subjects

Omar Calderón-Losada

Publications and source records attributed to Omar Calderón-Losada.

7 recordsLinked to original sources

arXiv2026

Linear-nonlinear duality for circuit design on quantum computing platforms

Beam splitters (BSs) and optical parametric amplifiers (OPAs) can be described using Lie groups $SU(2)$ and $SU(1,1)$. Here, we show that the dynamical trajectories of these devices are connected via a Wick rotation on their respective group manifolds. This yields an exact amplitude-level duality between BSs of transmittance $η$ and OPAs of gain $g=1/η$. This geometric correspondence admits a compact tensor-network formulation, which we use to construct a circuit-model protocol that reproduces PDC transition amplitudes. This construction naturally leads to finite-dimensional, truncated PDC unitaries that exactly reproduce the first $q$ amplitudes of an ideal parametric amplifier. Our results demonstrate that key amplitude-level features of nonlinear optical processes can be simulated using only native single-qubit unitaries and measurement-based primitives on existing digital quantum hardware. This extends PDC-inspired entanglement-generation mechanisms beyond photonic architectures.

quant-ph↗

arXiv2026

Deep learning parameter estimation and quantum control of single molecule

Coherent control, a central concept in physics and chemistry, has sparked significant interest due to its ability to fine-tune interference effects in atoms and individual molecules for applications ranging from light-harvesting complexes to molecular qubits. However, precise characterization of the system's dissipative dynamics is required for its implementation, especially at high temperature. In a quantum control experiment, this means learning system-bath parameters and driving coupling strengths. Here, we demonstrate how to infer key physical parameters of a single molecule driven by spectrally modulated pulses at room temperature. We develop and compare two computational approaches based on two-photon absorption photoluminescence signals: an optimization-based minimization scheme and a feed-forward neural network. The robustness of our approach highlights the importance of reliable parameter estimation in designing effective coherent control protocols. Our results have direct applications in ultrafast spectroscopy, quantum materials and technology.

quant-ph↗

arXiv2024

Generation of heralded vector-polarized single photons in remotely controlled topological classes

We demonstrate an experimental protocol for the preparation and control of heralded single photons in inhomogeneously polarized states, such as Vector Vortex and Full Poincaré beam states. A laser beam is shaped by a voltage-controlled spin-to-orbital angular momentum converter q-plate device which eliminates the need for an interferometer for the robust preparation of high-quality inhomogeneously polarized beams. Such a beam is then used as pump in a spontaneous parametric downconversion (SPDC) photon-pair source. We demonstrate the full pump to heralded single photon transfer of the intensity/phase distributions, as well as of the vector polarization structure. Additionally, we show that by controlling the polarization to which the heralding idler photon is projected before detection, we can toggle between the direct and basis-switched pump-single photon transfer. We show that this non-local control of the heralded single photon pertains also to the topological class of the resulting heralded single photon. We believe that our work will lead to new opportunities in photons-based quantum information processing science.

quant-ph↗

arXiv2021

Experimental study on the effects of photon-pair temporal correlations in entangled two-photon absorption

Entangled two-photon absorption (ETPA) has recently become a topic of lively debate, mainly due to the apparent inconsistencies in the experimentally-reported ETPA cross sections of organic molecules. In this work, we provide a thorough experimental study of ETPA in the organic molecules Rhodamine B (RhB) and Zinc Tetraphenylporphirin (ZnTPP). The goal of this contribution is twofold: on one hand, it seeks to reproduce the results of previous experimental reports and, on the other, it aims to determine the effects of different temporal correlations -- introduced as a controllable time-delay between the photons to be absorbed -- on the strength of the ETPA signal. In our experiment, the samples are excited by entangled pairs produced by type-I SPDC, with a spectral distribution centered at 810 nm. Surprisingly, and contrary to what was expected, the time delay did not produce in our experiments any systematic change in the cross-sections when monitoring the ETPA signal using a transmission measurement scheme. As a plausible cause of this unexpected result, we argue that the photon-pair flux, typically-used in these experiments, is not sufficient to promote the two-photon absorption process in these molecules. This suggests that the actual absorption cross-section values are lower than those previously reported, and therefore do not lead to a measurable ETPA effect for the transmission method.

quant-ph↗

arXiv2017

Implementation and characterization of a controllable dephasing channel based on coupling polarization and spatial degrees of freedom of light

We present the experimental implementation and theoretical model of a controllable dephasing quantum channel using photonic systems. The channel is implemented by coupling the polarization and the spatial distribution of light, that play, in the perspective of Open Quantum Systems, the role of quantum system and environment, respectively. The capability of controlling our channel allows us to visualize its effects in a quantum system. Differently from standard dephasing channels, our channel presents an exotic behavior in the sense that the evolution of a state, from a pure to a mixed state, shows an oscillatory behavior if tracked in the Bloch sphere. Additionally, we report the evolution of the purity and perform a quantum process tomography to obtain the χmatrix associated to our channel.

physics.optics↗

arXiv2016

Entangled two photon absorption cross section on the 808 nm region for the common dyes Zinc tetraphenylporphyrin and Rhodamine B

We report the measurement of the entangled two photon absorption cross section, $σ_E$, at 808 nm on organic chromophores in solution in a low photon flux regime. We performed measurements on Zinc tetraphenylporphyrin (ZnTPP) in Toluene and Rhodamine B (RhB) in Methanol. This is, to the best of our knowledge, the first time that $σ_E$ is measured for RhB. Additionally, we report a systematic study of the dependence of $σ_E$ on the molecular concentration for both molecular systems. In contrast to previous experiments, our measurements are based on detecting the pairs of photons that are transmitted by the molecular system. By using a coincidence count circuit it was possible to improve the signal to noise ratio. This type of work is important for the development of spectroscopic and microscopic techniques using entangled photons.

quant-ph↗

arXiv2015

Measuring different types of transverse momentum correlations in the biphoton's Fourier plane

In this work, we present a theoretical and experimental study about the spatial correlations of paired photons generated by type-II spontaneous parametric down-conversion. In particular, we show how these correlations can be positive or negative depending on the direction in which the far field plane is scanned and the polarization post-selected. Our results provide a straightforward way to observe different kind of correlations, that complement other well known methods to tune the spatial correlations of paired photons.

quant-ph↗