arXiv subjects

M. Asjad

Publications and source records attributed to M. Asjad.

14 recordsLinked to original sources

arXiv2025

Driven Magnon-Photon System as a Tunable Quantum Heat Rectifier

Controlling heat flow at the quantum level is a key challenge for next-generation quantum technologies, including thermal management and quantum information processing. Here, we investigate quantum heat transport in an asymmetrically driven hybrid magnon-photon system in contact with two thermal baths at different temperatures. We demonstrate that external driving of the magnonic subsystem provides a versatile control knob for tailoring steady-state heat currents and their asymmetry. We identify the mechanisms governing thermal rectification in the hybrid system: we find that strong rectification emerges in the regime of weak magnon-photon hybridization combined with intense magnon driving. In this regime, the external drive enables control over both the magnitude and direction of the heat current, allowing the rectification parameter to be tuned across its entire physically accessible range.

cond-mat.mes-hall↗

arXiv2024

Optomechanical cooling with simultaneous intracavity and extracavity squeezed light

We propose a novel and experimentally feasible approach to achieve high-efficiency ground-state cooling of a mechanical oscillator in an optomechanical system under the deeply unresolved sideband condition with the assistance of both intracavity and extracavity squeezing. In the scheme, a degenerate optical parametric amplifier is placed inside the optical cavity, generating the intracavity squeezing; besides, the optical cavity is driven by externally generated squeezing light, namely the extracavity squeezing. The quantum interference effect generated by intracavity squeezing and extracavity squeezing can completely suppress the non-resonant Stokes heating process while greatly enhancing the anti-Stokes cooling process. Therefore, the joint-squeezing scheme is capable of cooling the mechanical oscillators to their quantum ground state in a regime far away from the resolved sideband condition. Compared with other traditional optomechanical cooling schemes, the single-photon cooling rate in this joint-squeezing scheme can be tremendously enlarged by nearly three orders of magnitude. At the same time, the coupling strength required to achieve ground-state cooling can be significantly reduced. This scheme is promising for cooling large-mass and low-frequency mechanical oscillators, which provides a prerequisite for preparing and manipulating non-classical states in macroscopic quantum systems and lays a significant foundation for quantum manipulation.

quant-ph↗

arXiv2023

Parametrically enhancing sensor sensitivity at an exceptional point

We propose a scheme to enhance the sensitivity of Non-Hermitian optomechanical mass-sensors. The benchmark system consists of two coupled optomechanical systems where the mechanical resonators are mechanically coupled. The optical cavities are driven either by a blue or red detuned laser to produce gain and loss, respectively. Moreover, the mechanical resonators are parametrically driven through the modulation of their spring constant. For a specific strength of the optical driving field and without parametric driving, the system features an Exceptional Point (EP). Any perturbation to the mechanical frequency (dissipation) induces a splitting (shifting) of the EP, which scales as the square root of the perturbation strength, resulting in a sensitivity-factor enhancement compared with conventional optomechanical sensors. The sensitivity enhancement induced by the shifting scenario is weak as compared to the one based on the splitting phenomenon. By switching on parametric driving, the sensitivity of both sensing schemes is greatly improved, yielding to a better performance of the sensor. We have also confirmed these results through an analysis of the output spectra and the transmissions of the optical cavities. In addition to enhancing EP sensitivity, our scheme also reveals nonlinear effects on sensing under splitting and shifting scenarii. This work sheds light on new mechanisms of enhancing the sensitivity of Non-Hermitian mass sensors, paving a way to improve sensors performance for better nanoparticles or pollutants detection, and for water treatment.

quant-ph↗

arXiv2023

Emergence and enhancement of feedback control induced quantum entanglement

We present a scheme for controlling quantum correlations by applying feedback to the cavity mode that exits a cavity while interacting with a mechanical oscillator and magnons. In a hybrid cavity magnomechanical system with a movable mirror, the proposed coherent feedback scheme allows for the enhancement of both bipartite and tripartite quantum correlations. Moreover, we demonstrate that the resulting entanglement remains robust with respect to ambient temperatures in the presence of coherent feedback control.

quant-ph↗

arXiv2023

Nonlinear opto-vibronics in molecular systems

We analytically tackle opto-vibronic interactions in molecular systems driven by either classical or quantum light fields. In particular, we examine a simple model of molecules with two relevant electronic levels, characterized by potential landscapes with different positions of minima along the internuclear coordinate and of varying curvatures. Such systems exhibit an electron-vibron interaction, which can be comprised of linear and quadratic terms in the vibrational displacement. By employing a combination of conditional displacement and squeezing operators, we present analytical expressions based on a quantum Langevin equations approach, to describe the emission and absorption spectra of such nonlinear molecular systems. Furthermore, we examine the imprint of the quadratic interactions onto the transmission properties of a cavity-molecule system within the collective strong coupling regime of cavity quantum electrodynamics.

quant-ph↗

arXiv2023

Achieving Strong Magnon Blockade through Magnon Squeezing in a Cavity Magnetomechanical System

We propose a scheme to achieve magnon (photon) blockade by using magnon squeezing within a cavity magnomechanical system under weak pump driving. Under ideal conditions, we observe a substantial magnon blockade effect, as well as simultaneous photon blockade. Moreover, both numerical and analytical results match perfectly, providing robust evidence of consistency. In addition to calculating optimal parametric gain and detuning values, we can improve the second-order correlation function. The proposed scheme will be a pioneering approach towards magnon (photon) blockade in experimental cavity magnomechanical systems.

quant-ph↗

arXiv2023

Coherent feedback control of quantum correlations in cavity magnomechanical system with magnon squeezing

We address a scheme to enhance the quantum correlations in cavity opto-magnomechanical system by using the coherent feedback loop in the presence of magnon squeezing. The proposed coherent feedback-control allows a significant enhancement of the entanglement of three bipartite subsystems, i.e., photon-phonon, photon-magnon and phonon-magnon. We also study the Einstein-Podolsky-Rosen steering and one-way steering in the presence of thermal effects without imposing additional conditions of asymmetric losses or noises in the subsystems. Furthermore, we investigate the sensitiveness of the scheme to the magnon squeezing, and its performance in non-ideal situations in which losses and noises are taken into account.

quant-ph↗

arXiv2023

Quantum information entropy of heavy mesons in the presence of a point-like defect

Using Schr\"{o}dinger's formalism, we investigate the quantum eigenstates of the heavy mesons trapped by a point-like defect and by Cornell's potential. One implements this defect to the model considering a spherical metric profile coupled to it. Furthermore, the Nikiforov-Uvarov method is applied to theory to study the quantum eigenstates of the heavy mesons. To calculate the quantum information entropy (QIE), one considers the wave functions that describe the charmonium and bottomonium states. To explore the QIE, we use the well-known Shannon's entropy formulated at the position and reciprocal space. The analysis of the QIE gives us relevant information about how the quantum information change with the variation of the point-like defect. Consequently, considering the Bialynicki-Birula and Mycielski (BBM) relation, we show how this defect influences the quarkonium position and momentum uncertainty measures.

hep-ph↗

arXiv2022

Strong photon antibunching effect in a double cavity optomechanical system with intracavity squeezed light

We study the behaviour of the second-order correlation function in a double cavity optomechanical system and a degenerate optical parametric amplifier (OPA) is placed in each cavity. The first cavity is additionally driven by a weak classical laser field. The occurrence of strong photon antibunching effect in these two coupled cavities is observed. For suitable values of optomechanical coupling strength as well as photon hopping process, the system can exhibit a very strong photon antibunching effect. Our study also shows that the unconventional photon blockade occurs in both coupling, i.e. the weak coupling as well as in the strong coupling regimes as compared to the conventional photon blockade which occurs only in the strong coupling regime. We get a very strong photon antibunching effect under the unconventional photon blockade mechanism than the conventional photon blockade mechanism. Our study can be also used for the generation of single photon in coupled nonlinear optomechanical systems.

quant-ph↗

arXiv2022

Tunable Electromagnetically Induced Multi-Transparencies in Hybrid Optomechanical system Incorporating Atomic Medium

We consider a hybrid atom-optomechanical system incorporating N identical $\Lambda$-type atoms. The system is subjected to dual optical and phononic drives. We show that by exploiting the optomechanical linear and quadratic interactions, multiple electromagnetic transparency windows are attained. Furthermore, owing to the incorporated mechanical pump, the transparency windows are controlled and tuned. For instance, by adjusting the phase of the external mechanical pump, additional controlling parameters are enabled, and the absorption/emission profiles are enhanced. Our present study provides an efficient approach to modifying propagating signals inside the quantum devices incorporating cavity-optomechanical systems.

quant-ph↗

arXiv2022

Quantum information of the Aharanov-Bohm ring with Yukawa interaction in the presence of disclination

We investigate the quantum information by a theoretical measurement approach of an Aharanov-Bohm (AB) ring with Yukawa interaction in curved space with disclination. It obtained the so-called Shannon entropy, through the eigenfunctions of the system. The quantum states considered come from a Schroedinger theory with the AB field in the background of curved space. With this entropy, it can explore the quantum information at the position space and reciprocal space. Furthermore, we discussed how the magnetic field, the AB flux, and the topological defect influence the quantum states and the information entropy.

quant-ph↗

arXiv2022

Magnon squeezing enhanced ground-state cooling in cavity magnomechanics

Cavity magnomechanics has recently become a new platform for studying macroscopic quantum phenomena. The magnetostriction induced vibration mode of a large-size ferromagnet or ferrimagnet reaching its ground state represents a genuine macroscopic quantum state. Here we study the ground-state cooling of the mechanical vibration mode in a cavity magnomechanical system, and focus on the role of magnon squeezing in improving the cooling efficiency. The magnon squeezing is obtained by exploiting the magnon self-Kerr nonlinearity. We find that the magnon squeezing can significantly and even completely suppress the magnomechanical Stokes scattering. It thus becomes particularly useful in realizing ground-state cooling in the unresolved-sideband regime, where the conventional sideband cooling protocols become inefficient. We also find that the coupling to the microwave cavity plays only an adverse effect in mechanical cooling. This makes essentially the two-mode magnomechanical system (without involving the microwave cavity) a preferred system for cooling the mechanical motion, in which the magnon mode is established by a uniform bias magnetic field and a microwave drive field.

quant-ph↗

arXiv2022

Enhanced weak force sensing through atom-based coherent noise cancellation in a hybrid cavity optomechanical system

We investigate weak force-sensing based on coherent quantum noise cancellation in a nonlinear hybrid optomechanical system. The optomechanical cavity contains a moveable mechanical mirror, a fixed semitransparent mirror, an ensemble of ultracold atoms, and an optical parametric amplifier (OPA). Using the coherent quantum noise cancellation (CQNC) process, one can eliminate the back action noise at all frequencies. Also by tuning the OPA parameters, one can suppress the quantum shot-noise at lower frequencies than the resonant frequency. In the CQNC scheme, the damping rate of the mechanical oscillator matches the damping rate of the atomic ensemble, which is experimentally achievable even for a low-frequency mechanical oscillator with a high-quality factor. Elimination of the back action noise and suppression of the shot noise significantly enhance force sensing and thus overcome the standard quantum limit of weak force sensing. This hybrid scheme can play an essential role in the realization of quantum optomechanical sensors and quantum control.

quant-ph↗

arXiv2013

Robust stationary mechanical squeezing in a kicked quadratic optomechanical system

We propose a scheme for the generation of a robust stationary squeezed state of a mechanical resonator in a quadratically coupled optomechanical system, driven by a pulsed laser. The intracavity photon number presents periodic intense peaks suddenly stiffening the effective harmonic potential felt by the mechanical resonator. These "optical spring kicks" tend to squeeze the resonator position, and due to the interplay with fluctuation-dissipation processes one can generate a stationary state with more than 13 dB of squeezing even starting from moderately "pre-cooled" initial thermal states.

quant-ph↗