arXiv subjects

Esfandyar Faizi

Publications and source records attributed to Esfandyar Faizi.

8 recordsLinked to original sources

arXiv2025

Photocurrent Enhancement in a Generalized Quantum Photocell with Multi-Donor Architectures

In this study, we present a generalized quantum photocell model inspired by biological light-harvesting complexes, designed to probe the influence of donor multiplicity on photovoltaic performance. Building upon earlier two and three-donor systems, we introduce a scalable architecture comprising N independent donor molecules symmetrically arranged around a central acceptor. By modeling the system as a quantum heat engine and solving the master equation under the Born-Markov approximation, we uncover that increasing the number of donors leads to a superlinear enhancement in photocurrent and output power. Specifically, the current does not merely scale linearly with the number of donors but exhibits a marked increase due to collective excitation dynamics and enhanced charge transport. Our results reveal the critical role of donor network topology and aggregation in optimizing quantum photovoltaic efficiency and underscore the potential of biomimetic quantum architectures for next-generation solar energy conversion.

quant-ph↗

arXiv2024

Sensitivity of Photovoltaic Cells Efficiency to Initial Conditions in Various Aggregation Designs

It is thought that nature already exploits quantum mechanical properties to increase the efficiency of solar energy harvesting devices. So, the operation of these devices can be enhanced by clever design of a nanoscopic, quantum mechanical system where the quantum coherence plays a crucial role in this process. In this investigation, we develop a donor-acceptor two-level trap dipole model converging the key role of quantum coherence and aggregation effects along with different initial states. Our analysis reveals that quenching unwanted emissions is achievable by preparing the system in specific initial state under the effect of optimal spatial aggregation. Interestingly it is observed that characterizing aggregation-induced properties and quantum effects of bandgap engineering can increase the power enhancement up to 35.87% compared with classical counterparts. This encouraging trend suggests a promising novel design aspect of nature-mimicking photovoltaic devices.

cond-mat.mes-hall↗

arXiv2023

Selective weak measurement reveals super ergotropy

The concept of ergotropy was previously introduced as the maximum extractable work from a quantum state. Its enhancement, which is induced by quantum correlation via projective measurement, was formulated as the daemonic ergotropy. In this work, we investigate the ergotropy in the presence of quantum correlation via weak measurement because of its elegant effects on the measured system. By considering a bipartite correlated quantum system consisting of main and ancillary systems, we demonstrate that the extractable work by the non-selective weak measurement on the ancilla is always equal to the situation captured by the strong measurement. However, the selective weak measurement interestingly reveals more work than the daemonic ergotropy and the ergotropy of the total system is greater than or equal to the daemonic ergotropy. Moreover, it is shown that for Bell diagonal states, at the cost of losing quantum correlation, the total extractable and thus non-local extractable works can be increased by using measurement. Also, we find that there is no direct relationship between quantum correlation and non-local extractable work for these cases.

quant-ph↗

arXiv2022

Performance of quantum batteries with correlated and uncorrelated chargers

Energy can be stored in quantum batteries by electromagnetic fields as chargers. In this paper, the performance of a quantum battery with single and double chargers is studied. It is shown that by using two independent charging fields, prepared in coherent states, charging power of the quantum battery can be significantly improved, though the average number of embedded photons are kept the same in both scenarios. Then the results reveal that for the case of initially correlated states of the chargers the amount of extractable energy, measured by ergotropy, is more than initially uncorrelated ones, with appropriate degrees of field's intensities. Though the correlated chargers lead to greater reduction in purity of quantum battery, more energy and in turn, more ergotropy is stored in this case. In addition, we study the battery-charger mutual information and Von Neumann entropy and by using their relation, we find that both quantum and classical correlations are generated between the quantum battery and chargers. Then we study quantum consonance of the battery as the non-local coherence among it's cells and find some qualitative relations between the generation of such correlations and the capability of energy storage in the quantum battery.

quant-ph↗

arXiv2022

Quantum Coherent Route to Bath Induced Entanglement

The micromaser is an archetype experimental setting where a beam of excited two-level atoms is injected into a high-finesse cavity. It has played a pivotal role as a testbed for predictions of quantum optics. We consider a generalized micromaser setting consisting of high-quality cavity pumped by a beam of three-level atoms. The atoms are assumed to be prepared to carry quantum coherence between their excited state doublet. Our objective is to produce quantum entanglement between the right-handed circular (RHC) and left-handed circular (LHC) polarized photons in the cavity, exploiting the quantum coherence in the pump atoms. For that aim, we derive the generalized micromaser master equation for our system. We find that the dynamics of the micromaser field driven by the pump beam is equivalent to two non-interacting RHC and LHC photonis systems sharing a common non-equilibrium environment. The effect of the shared bath is to mediate an incoherent interaction between the otherwise non-interacting cavity photons, which emerges only if the atoms carry quantum coherence. We take into account cavity losses as a source of quantum decoherence and characterize the quantum entanglement between the LHC and RHC polarized photons in terms of logarithmic negativity, calculated using the dynamical solution of the master equation. Our reseults reveal that while there is no steady-state entanglement, LHC and RHC polarzied photons can be entangled in the transient regime.

quant-ph↗

arXiv2018

Protection of entanglement for a two-qutrit V-type open system on the basis of system-reservoir bound states

In this work, a mechanism for long time protection of entanglement of a two-qutrit V-type atomic system each of which interacts independently with a dissipative reservoir is investigated. It is shown that the protection process is related exclusively on the formation of bound states in the system-reservoir energy spectrum. It is demonstrated that the degree of boundedness for the system-reservoir bound states is well-controlled by entering other V-type qutrits into the reservoirs, and also through the manipulation of the spontaneously generated interference related to decay channels of the V-type atoms.

quant-ph↗

arXiv2017

Quantum coherence and entanglement preservation in Markovian and non-Markovian dynamics via additional qubits

In this paper, we investigate preservation of quantum coherence of a single-qubit interacting with a zero-temperature thermal reservoir through the addition of noninteracting qubits in the reservoir. Moreover, we extend this scheme to preserve quantum entanglement between two and three distant qubits, each of which interacts with a dissipative reservoir independently. At the long time limit, we obtained analytical expressions for the coherence measure and the concurrence of two and three qubits in terms of the number of additional qubits. It is observed that, by increasing the number of additional qubits in each reservoir, the initial coherence and the respective entanglements are completely protected in both Markovian and non-Markovian regimes. Interestingly, the protection of entanglements occurs even under the individually different behaviors of the reservoirs.

quant-ph↗

arXiv2016

An improved bound for quantum speed limit time in open quantum systems by introducing an alternative fidelity

In this paper, we introduce a new alternative quantum fidelity for quantum states which perfectly satisfies all Jozsas axioms and is zero for orthogonal states. By employing this fidelity, we derive an improved bound for quantum speed limit time in open quantum systems in which the initial states can be chosen as either pure or mixed. This bound leads to the well-known Mandelstamm-Tamm type bound for nonunitary dynamics in the case of initial pure states. However, in the case of initial mixed states, the bound provided by the introduced fidelity is tighter and sharper than the obtained bounds in the previous works.

quant-ph↗