arXiv subjects

John H. Reina

Publications and source records attributed to John H. Reina.

At least 19 recordsLinked to original sources

arXiv2026

Symmetry-Protected Quantum Synchronization in Squeezed-Bath-Engineered Superradiance

A squeezed dissipative bath converts the coupling phase of a bipartite unconventional Dicke model into a control parameter that suppresses both static superradiant thresholds, opening a window where only a Hopf instability survives and the two spin ensembles synchronize completely via the shared cavity mode. The squeezed bath preserves a $\mathbb{Z}_2$ parity symmetry, so conventional broken-symmetry diagnostics vanish identically. We certify the synchronized state instead through parity-even, information-theoretic witnesses: a 30\% photon-number suppression, a Husimi-$Q$ lobe-count change, a 64\% suppression of spin--spin mutual information, and a robust discord-to-mutual-information ratio $D/I = 0.50 \pm 0.05$, confirmed by full quantum master-equation simulations. These results establish parity-even witnesses as a general, entanglement-free route to certifying quantum synchronization in symmetry-protected driven-dissipative systems.

quant-ph↗

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

Entanglement and Dynamical Scaling Laws in Quantum Superabsorption

Quantum batteries (QBs) exploit collective quantum resources to surpass the limits of classical energy storage and power delivery. We analyze $N$-qubit cavity-coupled QBs governed by Dicke and Tavis--Cummings models under Gaussian driving and open-system dynamics. Finite-size scaling laws $\mathcal{O}(N)\!\sim\!N^α$ demonstrate an optimal region of relaxation and dephasing where coherent driving stabilizes entanglement entropy growth for thermodynamic observables (maximum energy $E_{\mathrm{max}}$, charging time $τ$, and maximum power $\bar{P}_{\mathrm{max}}$) and for qubit and cavity entanglement entropies. The Dicke model exhibits entropy-suppressed extensive behavior, while the Tavis--Cummings model achieves super-extensive scaling with $α_{E_{\mathrm{max}}}\!\in\![1.08,1.26]$, $α_τ\!\approx\!-0.49$, $α_{\bar{P}_{\mathrm{max}}}\!\in\![1.57,1.73]$, supported by qubit-cavity entanglement. We demonstrate that dissipation can act as a stabilizer source, yielding scaling benchmarks that are relevant to several experimental platforms. Our findings connect entanglement, dissipation-enhanced scaling laws and superabsorption, outlining a pathway towards scalable quantum batteries offering practical quantum advantage.

quant-ph↗

arXiv2026

Markovian heat engine boosted by quantum coherence

We evaluate the role of quantum coherence as a thermodynamic resource in a noisy, Markovian, one-qubit heat engine. By consuming the coherence of noisy quantum states, we demonstrate that the engine can surpass the classical efficiency limit when operating according to a quantum Otto cycle. The engine's non-classical nature is demonstrated by its violation of the Leggett-Garg's temporal correlations inequality. Amplitude damping increases the extractable work under partial thermalization, thereby increasing the efficiency. In contrast, phase damping increases the extractable work under partial thermalization but reduces the efficiency. We implement the entire Otto cycle in a quantum circuit, simulating realistic amplitude and phase damping channels, as well as gate-level noise. We introduce an operational measure of the circuit's thermodynamic cost to establish a direct link between energy consumption and information processing in quantum heat engines.

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↗

arXiv2023

Correlation-boosted quantum engine: A proof-of-principle demonstration

Employing currently available quantum technology, we design and implement a non-classically correlated SWAP heat engine that allows to achieve an efficiency above the standard Carnot limit. Such an engine also boosts the amount of extractable work, in a wider parameter window, with respect to engine's cycle in the absence of initial quantum correlations in the working substance. The boosted efficiency arises from a trade-off between the entropy production and the consumption of quantum correlations during the full thermodynamic cycle. We derive a generalized second-law limit for the correlated cycle and implement a proof-of-principle demonstration of the engine efficiency enhancement by effectively tailoring the thermal engine on a cloud quantum processor.

quant-ph↗

arXiv2022

Emergence of maximal hidden quantum correlations and its trade-off with the filtering probability in dissipative two-qubit systems

We investigate the behaviour of quantum CHSH-nonlocality, $\rm F_3$-steering, and usefulness for teleportation in an interacting two-qubit dissipative system. We show regimes where these three quantum correlations can be extracted by means of local filtering operations, despite them not being displayed in the bare natural time evolution. Moreover, we show the existence of local hidden state (LHS) and local hidden variable (LHV) models for some states during the dynamics and thus, showing that apparently-useless physical systems could still exhibit quantum correlations, which are hidden from us, but that can still be revealed by means of local filtering operations and therefore, displaying the phenomenon of \emph{hidden} quantum correlations. We furthermore show that there actually exists a trade-off between the amount of quantum correlations which can be extracted and the filtering probability with which such protocol can be implemented. From a theoretical point of view, the existence of such trade-off imposes a fundamental limit to the extraction of quantum correlations by local filtering operations. From a practical point of view on the other hand, the results here presented determine the amount of resources that should be invested in order to extract such maximal hidden quantum correlations.

quant-ph↗

arXiv2022

Neural-Network Quantum States: A Systematic Review

The so-called contemporary AI revolution has reached every corner of the social, human and natural sciences -- physics included. In the context of quantum many-body physics, its intersection with machine learning has configured a high-impact interdisciplinary field of study; with the arise of recent seminal contributions that have derived in a large number of publications. One particular research line of such field of study is the so-called Neural-Network Quantum States, a powerful variational computational methodology for the solution of quantum many-body systems that has proven to compete with well-established, traditional formalisms. Here, a systematic review of literature regarding Neural-Network Quantum States is presented.

quant-ph↗

arXiv2021

Photophysical Properties of BODIPY-derivatives for the Implementation of Organic Solar Cells: A Computational Approach

Solar cells based on organic compounds are a proven emergent alternative to conventional electrical energy generation. Here, we provide a computational study of power conversion efficiency optimization of BODIPY-derivatives by means of their associated open circuit voltage, short-circuit density, and fill factor. In so doing, we compute for the derivatives' geometrical structures, energy levels of frontier molecular orbitals, absorption spectra, light collection efficiencies, and exciton binding energies, via density functional theory (DFT) and time dependent (TD)--DFT calculations. We fully-characterize four D--$π$--A (BODIPY) molecular systems of high efficiency and improved $J_{sc}$ that are well suited for integration into bulk heterojunction (BHJ) organic solar cells as electron-donor materials in the active layer. Our results are two-fold: We found that molecular complexes with an structural isoxazoline ring exhibit a higher power conversion efficiency (PCE), a useful result for improving the BHJ current, and, on the other hand, by considering the molecular systems as electron-acceptor materials, with P3HT as the electron-donor in the active layer, we found a high PCE compound favorability with a pyrrolidine ring in its structure, in contrast to the molecular systems built with an isoxazoline ring. The theoretical characterization of the electronic properties of the BODIPY-derivatives here provided, computed with a combination of ab-initio methods and quantum models, can be readily applied to other sets of molecular complexes in order to hierarchize optimal power conversion efficiency.

physics.chem-ph↗

arXiv2021

Molecular Structure, Quantum Coherence and Solvent Effects on the Ultrafast Electron Transport in BODIPY--C$_{60}$ Derivatives

Molecular systems containing donor-bridge-acceptor sites or molecular antennas constitute promising candidates for organic photovoltaic device implementation. Photo-induced electron transfer in multi-chromophore molecular systems is defined by a subtle interaction between the donor and the molecular bridge, and by the system-solvent coupling. Here, we address the computation of quantum properties such as population inversion and electron transfer in molecular photo-systems composed of fulleroisoxazoline, fulleropyrrolidine, BODIPY and Zn-porphyrin, as well as their system-solvent ultrafast dynamics. The molecular complexes are modelled as two- and three-site systems, and we use the density functional theory (DFT) for obtaining the site energies required in the construction of the open system diabatic Hamiltonians relevant to the computation of the electron transfer. The site energies and electronic couplings are calculated by using a continuous polarizable model that allow for the analysis of different solvent environments, and the site-to-site couplings are computed by means of the generalized Mulliken Hush method at the DFT level. We find that the stabilization energy of the charge transfer states exhibit a significant variation for a compound embedded in different polar environments, and thus the effect due to the solvent has been analyzed for the specific cases of Methanol, THF and Toluene. We show that the incorporation of a molecular bridge generates the creation of an intermediate state that plays a crucial role in the charge transfer process by defining $Λ$ or cascaded-type energy schemes; this affects the asymptotic value of the transfer rate and favors the cascaded-type configuration.

physics.chem-ph↗

arXiv2020

Deep learning the atmospheric boundary layer height

A question of global concern regarding the sustainable future of humankind stems from the effect due to aerosols on the global climate. The quantification of atmospheric aerosols and their relationship to climatic impacts are key to understanding the dynamics of climate forcing and to improve our knowledge about climate change. Due to its response to precipitation, temperature, topography and human activity, one of the most dynamical atmospheric regions is the atmospheric boundary layer (ABL): ABL aerosols have a sizable impact on the evolution of the radiative forcing of climate change, human health, food security, and, ultimately, on the local and global economy. The identification of ABL pattern behaviour requires constant monitoring and the application of instrumental and computational methods for its detection and analysis. Here, we show a new method for the retrieval of ABL top arising from light detection and ranging (LiDAR) signals, by training a convolutional neural network in a supervised manner; forcing it to learn how to retrieve such a dynamical parameter on real, non-ideal conditions and in a fully automated, unsupervised way. Our findings pave the way for a full integration of LiDAR elastic, inelastic, and depolarisation signal processing, and provide a novel approach for real-time quantitative sensing of aerosols.

physics.ao-ph↗

arXiv2019

Experimental realisation of tunable ferroelectric/superconductor (BTO/YBCO)N/STO 1D photonic crystals in the whole visible spectrum

Emergent technologies that make use of novel materials and quantum properties of light states are at the forefront in the race for the physical implementation, encoding and transmission of information. Photonic crystals (PCs) enter this paradigm with optical materials that allow the control of light propagation and can be used for optical communication, and photonics and electronics integration making use of materials ranging from semiconductors, to metals, metamaterials, and topological insulators, to mention but a few. In particular, here we show how designer superconductor materials integrated into PCs fabrication allow for an extraordinary reduction of electromagnetic waves damping and possibilitate their optimal propagation and tuning through the structure, below critical superconductor temperature. We experimentally demonstrate, for the first time, a successful integration of ferroelectric and superconductor materials into a one-dimensional (1D) PC composed of (BTO/YBCO)N/STO bilayers that work in the whole visible spectrum, and below (and above) critical superconductor temperature (measured in the 10-300 K range). Theoretical calculations support, for different number of bilayers N, the effectiveness of the produced 1D PCs and pave the way for novel optoelectronics integration and information processing in the visible spectrum at low temperature, while preserving their electric and optical properties.

cond-mat.mtrl-sci↗

arXiv2019

Room Temperature Quantum Coherence vs. Electron Transfer in a Rhodanine Derivative Chromophore

Understanding electron transfer in organic molecules is of great interest in quantum materials for light harvesting, energy conversion, and integration of molecules into solar cells. This, however, poses the challenge of designing specific optimal molecular structure for which the processes of ultrafast quantum coherence and electron transport are not so well understood. In this work, we investigate subpicosecond time scale quantum dynamics and electron transfer in an efficient electron acceptor Rhodanine chromophoric complex. We consider an open quantum system approach to model the complex-solvent interaction and compute the crossover from weak to strong dissipation on the reduced system dynamics for both a polar (Methanol) and a non-polar solvent (Toluene). We show that the electron transfer rates are enhanced in the strong chromophore-solvent coupling regime, being the highest transfer rates those found at room temperature. Even though the computed dynamics are highly non-Markovian, and they may exhibit a quantum character up to hundreds of femtoseconds, we show that quantum coherence does not necessarily optimize the electron transfer in the chromophore.

physics.chem-ph↗

arXiv2019

Optical and Electronic Properties of Molecular Systems Derived from Rhodanine

Push-Pull functional compounds consisting of dicyanorhodanine derivatives have attracted a lot of interest because their optical, electronic, and charge transport properties make them useful as building blocks for organic photovoltaic implementations. The analysis of the frontier molecular orbitals shows that the vertical transitions of electronic absorption are characterized as intramolecular charge transfer; furthermore, we show that the analyzed compounds exhibit bathochromic displacements when comparing the presence (or absence) of solvent as an interacting medium. In comparison with materials defined by their energy of reorganization of electrons (holes) as electron (hole) transporters, we find a transport hierarchy whereby the molecule (Z)-2-((1,1-Dicyanomethylene)-5-(4-dimethylamino)benzylidene)-1,3-thiazol-4 is better at transporting holes than molecule (Z)-2-((1,1-Dicyanomethylene)-5-(tetrathiafulvalene-2-ylidene)-1,3-thiazol-4.

physics.chem-ph↗

arXiv2018

A first measurement of the Planetary Boundary Layer top in Cali-Colombia: Elastic LiDAR application

The monitoring of the impact of aerosols in Latin America on a local scale is usually limited due to the infrastructure and instrumentation available. In Colombia, there are two international ground surface monitoring networks, the AErosol RObotic NETwork (AERONET) and the Latin American LIDAR NETwork (LALINET). However, the AERONET performance relies on only one sun photometer which makes measurements distributed among five ground-based stations in different cities such as Bogotá and Medellín. On the other hand, LALINET has only one ground-based station formed by an elastic LiDAR system located at Medellín. Although Cali is the largest city of Colombian southwestern, with an accelerated grown rate of both urban and vehicular fleet, and counts with the third largest population of this country, is not reached by these networks. Here, we report on the implementation of a monostatic-coaxial multispectral LiDAR system using a pulsed Nd:YAG laser with 450 mJ of average energy at 1064 nm. To perform the atmospheric measurements, this system is capable of spatially resolving elastic backscatter down to 3.75 m with a Pulse Repetition Frequency (PRF) of 10 Hz. We have developed a hybrid algorithm for data analysis by combining the Fitting and Gradient method and the Klett-Fernald algorithm to estimate the Planetary Boundary Layer (PBL) Top and the optical properties of aerosols. This work constitutes the first quantitative atmospheric exploration to study the aerosols dynamics and the PBL in the northwest of South America.

physics.ao-ph↗

arXiv2018

Conditional quantum nonlocality in dimeric and trimeric arrays of organic molecules

Arrays of covalently bound organic molecules possess potential for light-harvesting and energy transfer applications due to the strong coherent dipole-dipole coupling between the transition dipole moments of the molecules involved. Here, we show that such molecular systems, based on perylene-molecules, can be considered as arrays of qubits that are amenable for laser-driven quantum coherent control. The perylene monomers exhibit dephasing times longer than four orders of magnitude a typical gating time, thus allowing for the execution of a large number of gate operations on the sub-picosecond timescale. Specifically, we demonstrate quantum logic gates and entanglement in bipartite (dimer) and tripartite (trimer) systems of perylene-based arrays. In dimers, naturally entangled states with a tailored degree of entanglement can be produced. The nonlocality of the molecular trimer entanglement is demonstrated by testing Mermin's (Bell-like) inequality violation.

quant-ph↗

arXiv2017

Not-Post-Peierls compatibility under noisy channels

The Pusey-Barrett-Rudolph (PBR) theorem deals with the realism of the quantum states. It establishes that every pure quantum state is real, in the context of quantum ontological models. Specifically, by guaranteeing the property of not-Post-Peierls ($\neg$PP) compatibility (or antidistinguishability) for a particular set of states $P$, together with the ad hoc postulate known as Preparation Independence Postulate (PIP), the theorem establishes that these two properties imply the $ψ$-onticity (realism) of the set of all pure states. This PBR result has triggered two particular lines of research: On the one hand, it has been possible to derive similar results without the use of the PIP, although at the expense of implying weaker properties than $ψ$-onticity. On the other hand, it has also been proven that the property of $\neg$PP compatibility alone is an explicit witness of usefulness for the task known as conclusive exclusion of states. In this work, we explore the $\neg$PP compatibility of the set of states $P$, when $P$ is under the interaction of some noisy channels, which would consequently let us identify some noisy scenarios where it is still possible to perform the task of conclusive exclusion of states. Specifically, we consider the set $P$ of $n$-qubit states in interaction with an environment by means of i) individual and ii) collective couplings. In both cases, we analytically show that the phenomenon of achieving $\neg$PP compatibility, although reduced, it is still present. Searching for an optimisation of this phenomenon, we report numerical experiments up to $n=4$ qubits.

quant-ph↗

arXiv2016

On the Activation of Quantum Nonlocality

We report on some quantum properties of physical systems, namely, entanglement, nonlocality, $k$-copy nonlocality (superactivation of nonlocality), hidden nonlocality (activation of nonlocality through local filtering) and the activation of nonlocality through tensoring and local filtering. The aim of this work is two-fold. First, we provide a review of the numerical procedures that must be followed in order to calculate the aforementioned properties, in particular, for any two-qubit system, and reproduce the bounds for two-qudit Werner states. Second, we use such numerical tools to calculate new bounds of these properties for two-qudit Isotropic states and two-qubit Hirsch states.

quant-ph↗