arXiv subjects

Amarendra K. Sarma

Publications and source records attributed to Amarendra K. Sarma.

At least 37 records · Page 2Linked to original sources

arXiv2023

Quantum interference induced magnon blockade and antibunching in a hybrid quantum system

In this work, we study the phenomena of quantum interference assisted magnon blockade and magnon antibunching in a weakly interacting hybrid ferromagnet-superconductor system. The magnon excitations in two yttrium iron garnet spheres are indirectly coupled to a superconducting qubit through microwave cavity modes of two mutually perpendicular cavities. We find that when one of the magnon mode is driven by a weak optical field, the destructive interference between more than two distinct transition pathways restricts simultaneous excitation of two magnons. We analyze the magnon correlations in the driven magnon mode for the case of zero detunings as well as finite detunings of the magnon modes and the qubit. We show that the magnon antibunching can be tuned by changing the magnon-qubit coupling strength ratio and the driving detuning. Our work proposes a possible scheme which have significant role in the construction of single magnon generating devices.

quant-ph↗

arXiv2022

Tutorial: Cavity Quantum Optomechanics

Exploring quantum physics in macroscopic systems and manipulating these systems for various technological applications has been a topic of intense research in the last one decade or so. In this regard, the field of cavity quantum optomechanics turns out to be one of the most rapidly emerging area of research. It has opened many doors to study various open ended fundamental questions in quantum physics, apart from numerous possible applications. A typical cavity optomechanical system consists of two mirrors, one fixed while the other one is movable. These systems may be of micrometer or nano-meter in dimensions. The electromagnetic radiation incident on the system may get coupled to the mechanical motion of the movable mirror. This opto-mechanical coupling is the root of all phenomena such as quantum entanglement, state-transfer, squeezing and so on. In this short tutorial, basic concepts of cavity quantum optomechanics are discussed. We hope that this tutorial would motivate readers, both theorists and experimentalists, to take up advanced studies in this immensely fruitful area of research.

quant-ph↗

arXiv2022

Bistable soliton switching dynamics in a $\mathcal{PT}$-symmetric coupler with saturable nonlinearity

We investigate the switching dynamics in a $\mathcal{PT}$-symmetric fiber coupler composed of a saturable nonlinear material as the core. In such a saturable nonlinear medium, bistable solitons may evolve due to the balance between dispersion and saturable nonlinearity, which we extend in the context of the $\mathcal{PT}$-symmetric coupler. Our investigations of power-controlled and phase-sensitive switching show richer soliton switching dynamics than the currently existing conventional counterparts, which may lead to ultrafast and efficient all-optical switching dynamics at very low power owing to the combined effects of $\mathcal{PT}$ symmetry and saturable nonlinearity. In addition to the input power, the relative phase of the input solitons and saturable coefficient are additional controlling parameters that efficiently tailor the switching dynamics. Also, we provide a suitable range of system and pulse parameters that would be helpful for the practical realization of the coupler to use in all-optical switching devices and photonic circuits. Finally, we develop a variational approach to analytically investigate the switching dynamics in such $\mathcal{PT}$-symmetric couplers that excellently predicts the numerical findings.

physics.optics↗

arXiv2022

Mechanical Squeezing in Quadratically-coupled Optomechanical Systems

We demonstrate the generation of a strong mechanical squeezing in a dissipative optomechanical system by introducing a periodic modulation in the amplitude of a single-tone laser driving the system. The mechanical oscillator is quadratically coupled to the optical mode, which contributes to a strong squeezing exceeding the 3-dB standard quantum limit. The Bogoliubov mode of the mechanical oscillator also cools down to its ground state due to sideband cooling. We further optimize this ratio of sideband strengths to introduce enhanced squeezing. We also compare our results with the analytical (under adiabatic approximation) and the exact numerical solution. Even for a thermal occupancy of 10^4 phonons, mechanical squeezing beyond 3 dB and a strong optomechanical entanglement is observed.

quant-ph↗

arXiv2022

Switching dynamics of femtosecond solitons in parity-time-symmetric coupled optical waveguides

We report a detailed study on soliton steering dynamics in a parity-time-symmetric directional coupler in the femtosecond domain, which requires incorporation of higher-order perturbative effects such as third-order and fourth-order dispersions, self-steepening, and intrapulse Raman scattering. With a high gain/loss, the combination of all these effects is found to stabilize the soliton pulse evolution in the coupler from the chaotic behavior of unperturbed evolution. This work demonstrates that efficient soliton steering can be achieved at very low critical power and a relatively higher gain/loss even in the femtosecond regime.

physics.optics↗

arXiv2022

Two-way enhancement of sensitivity by tailoring higher-order exceptional points

Higher-order exceptional points in non-Hermitian systems have recently been used as a tool to engineer high-sensitivity devices, attracting tremendous attention from multidisciplinary fields. Here, we present a simple yet effective scheme to enhance the device sensitivity by slightly deviating the gain-neutral-loss linear configuration to a triangular one, resulting in an abrupt phase transition from third-order to second-order exceptional points. Our analysis demonstrates that the exceptional points can be tailored by a judicious tuning of the coupling parameters of the system, resulting in enhanced sensitivity to a small perturbation. The tunable coupling also leads to a sharp change in the sensitivity slope, enabling the perturbation to be measured precisely as a function of coupling. This two-way detection of the perturbation opens up a rich landscape toward ultra-sensitive measurements, which could be applicable to a wide range of non-Hermitian ternary platforms.

physics.optics↗

arXiv2022

Variational approach to study solitary waves in $\mathcal{PT}$-symmetric nonlinear couplers

We theoretically investigate the solitary waves and their switching dynamics in a $\mathcal{PT}$-symmetric directional fiber coupler, exhibiting Kerr nonlinearity, by developing a variational analysis. We analyze the fundamental switching characteristics of the $\mathcal{PT}$-symmetric Kerr coupler in the picosecond timescale by considering the coupled-mode equation for the unperturbed nonlinear Schrödinger equation, which we compare to its conventional counterpart. The impacts of higher-order perturbations (intrapulse Raman scattering, self-steepening, and third-order dispersion) are investigated in detail in the femtosecond timescale. In all cases, the variational method successfully predicts each of the numerically observed switching characteristics. Our semianalytical treatment has the potential to provide physical insights into complex switching dynamics in various nonlinear coupler configurations from different areas of physics.

physics.optics↗

arXiv2022

Synchronization of a superconducting qubit to an optical field mediated by a mechanical resonator

We study the synchronization of a superconducting qubit to an external optical field via a mechanical resonator in a hybrid optoelectromechanical system. The quantum trajectory method is employed to investigate synchronization. The bistability in one of the qubit polarization vectors, where the qubit rotates about the polarization vector, is observed for a single quantum trajectory run. The rotation in one of the stable states is synced with the external optical drive. When the number of trajectories is significantly increased, the qubit no longer displays bistability. However, synchronization with less quantum fluctuations is still observed. The scheme could be used to transfer the phase of the microwave qubit's rotation to a long-lived optical photon through synchronization, which may find applications in long-distance quantum communication. Also, this hybrid system can be used to study quantum synchronization.

quant-ph↗

arXiv2021

Effective optoelectrical entanglement and strong mechanical squeezing in a multi-modulated optoelectromechanical system

We propose effective generation of entangled and squeezed states in an optoelectromechanical system comprising of a macroscopic LC electrical circuit and an optomechanical system. We obtain enhanced entanglement between optical and LC circuit modes that are coupled via a common mechanical mode in the microwave regime. We achieve this enhancement by a stepwise application of modulation in the laser drive, the voltage drive and the spring constant of the moveable end-mirror. The maximum amount of entanglement is observed to be primarily dependent on the voltage modulation and changes slightly with the parameters of the spring constant. Alongside the generated entanglement, we also study the variation of the maximum degree of squeezing in the mechanical mode for different parameter regimes.

quant-ph↗

arXiv2021

Coherent Control of Hyperfine States and Slow and Fast Light Switching in Ultracold Atoms

We propose a scheme for attaining slow and fast light via coherent control of the hyperfine ground and excited states of an ultracold atomic system. The proposed scheme is theoretically analyzed for the $D_1$ transition of ultracold $^{23}$ Na atoms. The role of field detuning and field intensity on both the population transfer and induced polarization is investigated. It is shown that slow and fast light, with large bandwidth could be obtained in the proposed system. It is inferred that both slow and fast light could co-propagate, pertaining to different optical and Raman transitions. Further, it is observed that switching between the slow and the fast light is achievable by controlling the field intensity, as well as the field detuning.

quant-ph↗

arXiv2021

Ground-State Cooling of a Mechanical Oscillator via a Hybrid Electro-Optomechanical System

We present a scheme for ground-state cooling of a mechanical resonator by simultaneously coupling it to a superconducting qubit and a cavity field. The Hamiltonian describing the hybrid system dynamics is systematically derived. The cooling process is driven by a red-detuned ac drive on the qubit and a laser drive on the optomechanical cavity. We have investigated cooling in the weak and the strong coupling regimes for both the individual system, i.e., qubit assisted cooling and optomechanical cooling, and compared them with the effective hybrid cooling. It is shown that hybrid cooling is more effective compared to the individual cooling mechanisms, and could be applied in both the resolved and the unresolved sideband regimes.

quant-ph↗

arXiv2021

Chaos in Qubit Coupled Optomechanical Systems

We have found stable chaotic solutions for optomechanical systems coupled with a Two-Level System or qubit. In this system methods have been found which can be used to Tune in and out of Chaos as well as various n-period motions. This includes achieving chaos by changing the detuning, coupling parameters, and Power of the driving laser. This allows us to manipulate chaos using either the qubit or the optical cavity. Chaotic motion was also observed in both the qubit and cavity by only changing the relative phase between of driving fields of the two. This gives us the prospect of creating and exploring chaotic motion in quantum mechanical systems with further ease

quant-ph↗

arXiv2021

Transitionless phonon assisted photon-qubit quantum state transfer in a hybrid optomechanical system

Quantum state transfer is crucial for quantum information processing and quantum computation. Here, we propose a hybrid optomechanical system capable of coupling a qubit, an optical mode and a mechanical oscillator. The displacement of the mechanical oscillator,due to radiation pressure, induces spatial variation in the cavity field, which in turn couples the qubit with phonon mode. This allows state transfer between the cavity mode and the qubit without an actual interaction between them. We present a scheme for the transitionless quantum state transfer based on the transitionless quantum driving algorithm allowing us to achieve perfect state transfer.

quant-ph↗

arXiv2021

Controllable Kuznetsov Ma-like breather generation via dispersion modulation in the nonlinear Schrödinger equation with variable coefficients

The nonlinear Schrödinger equation with variable coefficients has applications in numerous areas of physics,specifically in the context of nonlinear optics and Bose-Einstein condensate. Apart from the usual bright and dark-soliton solutions, the so-called rational soliton solutions are perceived to have tremendous impact in futuristic applications and understanding many natural phenomena. In this work, we have studied various orders of rational solution of the variable coefficient nonlinear Schrödinger equation. It is possible to extract the first and the second-order controlled KM-like breather by periodic modulation of the dispersion along the propagation direction. The amplitude of the dispersion modulation controls the background as well as the breather peak power in the case of the first-order rational soliton solution, whereas the spatial frequency controls the breathing frequency of the KM-like breather. Our study reveals that it is possible to obtain various new features in the third order rational soliton by modulating the dispersion parameter.

nlin.PS↗

arXiv2020

Dispersion Managed Generation of Peregrine Solitons and Kuznetsov-Ma Breather in an Optical Fiber

Optical rogue waves and its variants have been studied quite extensively in the context of optical fiber in recent years. It has been realized that dispersion management in optical fiber is experimentally much more feasible compared to its nonlinear counterpart. In this work, we report Kuznetsov-Ma (KM)-like breathers from the first three orders of rational solutions of the nonlinear Schrödinger equation with periodic modulation of the dispersion coefficient along the fiber axis. The breather dynamics are then controlled by proper choice of modulating parameters. Additionally, the evolution of new one-peak and two-peak breather-like solutions has been displayed corresponding to the second-order rational solution. Direct numerical simulations based on modulational instability has also been executed which agree well with the analytical results, thereby making the proposed system more feasible for experimental realization.

physics.optics↗

arXiv2019

Multifaceted nonlinear dynamics in $\mathcal{PT}$-symmetric coupled Liénard oscillators

We propose a generalized parity-time ($\mathcal{PT}$) -symmetric Liénard oscillator with two different orders of nonlinear position-dependent dissipation. We study the stability of the stationary states by using the eigenvalues of Jacobian and evaluate the stability threshold thereafter. In the first order nonlinear damping model, we discover that the temporal evolution of both gain and lossy oscillators attains a complete convergence towards the stable stationary state leading to the emergence of oscillation and amplitude deaths. Also, the system displays a remarkable manifestation of transient chaos in the lossy oscillator while the gain counterpart exhibits blow-up dynamics for certain choice of initial conditions and control parameters. Employing an external driving force on the loss oscillator, we find that the blow-up dynamics can be controlled and a pure aperiodic state is achievable. On the other hand, the second order nonlinear damping model yields a completely different dynamics on contrary to the first order where the former reveals a conventional quasi-periodic route to chaos upon decreasing the natural frequency of both gain and loss oscillators. An electronic circuit scheme for the experimental realization of the proposed system has also been put forward.

nlin.CD↗

arXiv2019

Quantum synchronization and correlation in bidirectionally and unidirectionally coupled optomechanical oscillators

Optically coupled optomechanical oscillators has turned out to be a versatile experimental resource for exploring optomechanical synchronizations and correlations. In this work, we investigate the phenomena of quantum synchronization and quantum correlations in two optically coupled optomechanical oscillators with two different topologies. In one case the oscillators are coupled with optical photons in a reversible manner, termed as bidirectional coupling, while in the other photons are allowed to enter to the other oscillator but not allowed to exchanged back in the opposite direction, termed as unidirectional coupling. Our results shows that irrespective of these configurations, when synchronization builds up, the two oscillators also become quantum mechanically correlated with a finite degree of Gaussian quantum discord. However, we find that depending on these topologies, both synchronization and quantum discord behave in a very distinctive manner. For instance, in bidirectionally coupled optomechanical oscillators, we find both quantum synchronization and discord exhibit a tongue like pattern which is the quantum analogue of an Arnold tongue. Whereas, in the unidirectionally coupled oscillators, we observe a novel blockade like behavior for quantum phase synchronization, also known as the quantum synchronization blockade, while quantum discord being failed to map such an anomalous behavior.

quant-ph↗

arXiv2019

Surface polaritonic solitons and breathers in a planar plasmonic waveguide structure via electromagnetically induced transparency

We propose a scheme for the coupler-free excitation of surface polaritonic solitons and breathers in a planar plasmonic waveguide structure comprising of a transparent layer, a metal layer and a layer of three-level lambda-type atomic medium. In the proposed system, an enhanced Kerr nonlinearity is achieved via electromagnetically induced transparency (EIT) in the bottom atomic medium, which can be controlled through proper modulation of the frequency detunings and Rabi frequencies of the driving laser fields. This nonlinearity balances the dispersion in the system, thus providing the necessary condition for the excitation of polaritonic solitons in the proposed system. As a result, the system yields laterally self-trapped bright and dark surface polaritonic solitons which are tightly guided at the interface of the metal and the EIT medium. Furthermore, we investigate the excitation of surface polaritonic Akhmediev breathers at the metal-EIT medium interface in the proposed system. A stable propagation of the surface polaritonic Akhmediev breathers is achieved with proper choice of parameters in the proposed planar plasmonic waveguide structure. This experimentally feasible scheme could be significant in the development of highly compact nano-photonic devices in the optical regime.

physics.optics↗