Dissipative Coupling Research Articles

Dissipative coupling for the seismic enhancement of adjacent structures

Dissipative coupling for the seismic enhancement of adjacent structures

Spin number dependent dissipative coupling strength

A system consisting of a yttrium iron garnet (YIG) sphere coupled to a 1D circular-rectangular cavity is tuned between level repulsion and attraction by rotating the angular position of the YIG sphere within the cavity. The dominance of coherent or dissipative coupling mechanisms was determined, and the coupling strength was deduced by fitting the transmission spectra. By changing the diameter of the YIG sphere from 0.5 mm to 0.3 mm and 1.0 mm, we confirm that the N scaling of coherent coupling strength is also applicable in dissipative coupling. A large YIG sphere leads to an enhanced coupling strength that is useful for information processing. Alternatively, a small YIG sphere results in a narrow transition regime, which may be helpful for identifying the dissipative coupling dominated regime and providing insight into the physical origin of dissipative coupling.

The optical control of phase locking of polariton condensates

The phase and the frequency of an exciton polariton condensate excited by a nonresonant pump can be efficiently manipulated by an external coherent light. Being tuned close to the resonance with the condensate eigenfrequency, the external laser light imposes its frequency to the condensate and locks its phase, thereby manifesting a synchronization effect. The conditions of formation of the phase synchronized regime are determined. The synchronization of a couple of closely spaced polariton condensates by a spatially uniform coherent light is examined. At the moderate strength of the coherent driving the synchronization is accompanied by the appearance of symmetry-breaking states of the polariton dyad, while these states are superseded by the symmetric state at the high-intensity driving. By employing a zero-dimensional model of coupled dissipative oscillators with both dissipative and conservative coupling, we study the bifurcation scenario of the symmetry-breaking state formation.

Mode discrimination in dissipatively coupled laser arrays.

We show that dissipative coupling between an array of passive optical resonators creates a ladder of decay rates in the complex eigenfrequencies. This effect promotes mode discrimination in laser arrays, while the lowest-order and highest-order modes exhibit the highest and lowest lasing thresholds, respectively. The array supermodes and their corresponding eigenfrequencies are calculated analytically through a tight-binding model, and the single-mode operation range is derived. The results are exemplified through the finite element simulation of an array of transversely coupled semiconductor laser cavities.

Quantum Probing Topological Phase Transitions by Non‐Markovianity

AbstractUnderstanding the physical significance and probing the global invariants characterizing quantum topological phases in extended systems is a main challenge in modern physics with major impact in different areas of science. Here, a quantum‐information‐inspired probing method is proposed where topological phase transitions are revealed by a non‐Markovianity quantifier. The idea is illustrated by considering the decoherence dynamics of an external read‐out qubit that probes a Su–Schrieffer–Heeger (SSH) chain with either pure dephasing or dissipative coupling. Qubit decoherence features and non‐Markovianity measure clearly signal the topological phase transition of the SSH chain.

Traveling wave into an unstable state in dissipative oscillator chains

Coupled oscillators can exhibit complex spatiotemporal dynamics. Here, we study the propagation of nonlinear waves into an unstable state in dissipative coupled oscillators. To this, we consider the dissipative Frenkel–Kontorova model, which accounts for a chain of coupled pendulums or Josephson junctions and coupling superconducting quantum interference devices. As a function of the dissipation parameter, the front that links the stable and unstable state is characterized by having a transition from monotonous to non-monotonous profile. In the conservative limit, these traveling nonlinear waves are unstable as a consequence of the energy released in the propagation. Traveling waves into unstable states are peculiar of dissipative coupling systems. When the coupling and the dissipation parameter are increased, the average front speed decreases. Based on an averaging method, we analytically determine the front speed. Numerical simulations show a quite fair agreement with the theoretical predictions. To show that our results are generic, we analyze a chain of coupled logistic equations. This model presents the predicted dynamics, opening the door to investigate a wider class of systems.

Fission dynamics of Pu240 from saddle to scission and beyond

Calculations are presented for the time evolution of $^{240}\mathrm{Pu}$ from the proximity of the outer saddle point until the fission fragments are well separated, using the time-dependent density functional theory extended to superfluid systems. We have tested three families of nuclear energy density functionals and found that all functionals exhibit a similar dynamics: The collective motion is highly dissipative and with little trace of inertial dynamics, due to the one-body dissipation mechanism alone. This finding justifies the validity of using the overdamped collective motion approach and to some extent the main assumptions in statistical models of fission. This conclusion is robust with respect to the nuclear energy density functional used. The configurations and interactions left out of the present theory framework only increase the role of the dissipative couplings. An unexpected finding is varying the pairing strength within a quite large range has only minor effects on the dynamics. We find notable differences in the excitation energy sharing between the fission fragments in the cases of spontaneous and induced fission. With increasing initial excitation energy of the fissioning nucleus, more excitation energy is deposited in the heavy fragment, in agreement with experimental data on average neutron multiplicities.

Nonreciprocity and Unidirectional Invisibility in Cavity Magnonics.

We reveal the cooperative effect of coherent and dissipative magnon-photon couplings in an open cavity magnonic system, which leads to nonreciprocity with a considerably large isolation ratio and flexible controllability. Furthermore, we discover unidirectional invisibility for microwave propagation, which appears at the zero-damping condition for hybrid magnon-photon modes. A simple model is developed to capture the generic physics of the interference between coherent and dissipative couplings, which accurately reproduces the observations over a broad range of parameters. This general scheme could inspire methods to achieve nonreciprocity in other systems.

Cavity-mediated dissipative coupling of distant magnetic moments: Theory and experiment

We investigate long-range coherent and dissipative coupling between two spatially separated magnets while both are coupled to a microwave cavity. A careful examination of the system shows that the indirect interaction between two magnon modes is dependent on their individual mechanisms of direct coupling to the cavity. If both magnon modes share the same form of coupling to the cavity (either coherent or dissipative), then the indirect coupling between them will produce level repulsion. Conversely, if the magnon modes have different forms of coupling to the cavity (one coherent and one dissipative), then their indirect coupling will produce level attraction. We further demonstrate the cavity-mediate nature of the indirect interaction through investigating the dependence of the indirect coupling strength on the frequency detuning between the magnon and cavity modes. Our work theoretically and experimentally explores indirect cavity mediate interactions in systems exhibiting both coherent and dissipative coupling, which opens a new avenue for controlling and utilizing light-matter interactions.

Dissipative coupling for the seismic enhancement of adjacent structures

The paper suggests a procedure for the seismic improvement of adjacent structures. The control strategies that constitute the core of the methodology are based on the performance of a simple linear analytical model composed by two simple oscillators linked by a dissipative element. The constitutive behavior of the dissipative connection is described by a Kelvin-Voigt model. For such system, have been defined some optimal configurations depending by the eigenvalue coalescence or by the stochastic linear response. The use of simplified model can provide a rapid and well-approximate choice of the dampers mechanical characteristics. Moreover, the procedure will offer a varied scenario of possibilities where the optimal choice will depend also by the aim to be achieved (e.g. minimum of accelerations or displacements). In particular, has been proposed a new weighted performance that take into account the cost and energy issued by the damper helping the designer in the choice of the best damper. The final step is related to a refinement of the parameter selection through a nonlinear analysis. Such approach has been adopted for the seismic improvements of the Edifice A of the Faculty of Engineering of University of L’Aquila heavily destroyed during the 2009 L’Aquila Earthquake, here reported as case study.

Flexure-tuned membrane-at-the-edge optomechanical system.

We introduce a passively-aligned, flexure-tuned cavity optomechanical system in which a membrane is positioned microns from one end mirror of a Fabry-Perot optical cavity. By displacing the membrane through gentle flexure of its silicon supporting frame (i.e., to ∼80 m radius of curvature (ROC)), we gain access to the full range of available optomechanical couplings, finding also that the optical spectrum exhibits none of the abrupt discontinuities normally found in "membrane-in-the-middle" (MIM) systems. More aggressive flexure (3 m ROC) enables >15 μm membrane travel, milliradian tilt tuning, and a wavelength-scale (1.64 ± 0.78 μm) membrane-mirror separation. We also provide a complete set of analytical expressions for this system's leading-order dispersive and dissipative optomechanical couplings. Notably, this system can potentially generate orders of magnitude larger linear dissipative or quadratic dispersive strong coupling parameters than is possible with a MIM system. Additionally, it can generate the same purely quadratic dispersive coupling as a MIM system, but with significantly suppressed linear dissipative back-action (and force noise).

Impact of pressure dissipation on fluid injection into layered aquifers

Carbon dioxide ($\text{CO}_{2}$) capture and subsurface storage is one method for reducing anthropogenic $\text{CO}_{2}$ emissions to mitigate climate change. It is well known that large-scale fluid injection into the subsurface leads to a buildup in pressure that gradually spreads and dissipates through lateral and vertical migration of water. This dissipation can have an important feedback on the shape of the $\text{CO}_{2}$ plume during injection, but the impact of vertical pressure dissipation, in particular, remains poorly understood. Here, we investigate the impact of lateral and vertical pressure dissipation on the injection of $\text{CO}_{2}$ into a layered aquifer system. We develop a compressible, two-phase model that couples pressure dissipation to the propagation of a $\text{CO}_{2}$ gravity current. We show that our vertically integrated, sharp-interface model is capable of efficiently and accurately capturing water migration in a layered aquifer system with an arbitrary number of aquifers. We identify two limiting cases – ‘no leakage’ and ‘strong leakage’ – in which we derive analytical expressions for the water pressure field for the corresponding single-phase injection problem. We demonstrate that pressure dissipation acts to suppress the formation of an advancing $\text{CO}_{2}$ tongue during injection, reducing the lateral extent of the plume. The properties of the seals and the number of aquifers determine the strength of pressure dissipation and subsequent coupling with the $\text{CO}_{2}$ plume. The impact of pressure dissipation on the shape of the $\text{CO}_{2}$ plume is likely to be important for storage efficiency and security.

Stable optical rigidity based on dissipative coupling

We show that stable optical rigidity can be obtained in a Fabry–Perot cavity having pure dissipative optomechanical coupling and detuned pumping under corresponding conditions. Optical detection of a weak classical mechanical force is analyzed under this rigidity. The sensitivity of small force measurement can be better than the standard quantum limit.

Cavity-mediated dissipative spin-spin coupling

We study dissipative spin-spin coupling in a dispersive regime mediated by virtual photons in a microwave cavity. Dissipative coupling between spin of each magnetic material and the cavity photons is established by means of two phase-shifted driving forces acting on each spin. We show that mode-level attraction between two spin modes can be reached when one of the spins is dissipatively coupled to the cavity. By tuning the phase parameter at each ferromagnetic insulator, we can shift the order of ``dark'' and ``bright'' collective modes with the phase difference equal to 0 or $\ensuremath{\pi}$. Moreover, by selectively applying the phase-shifted field, it is possible to construct dark and bright collective modes with the phase difference equal to $\ifmmode\pm\else\textpm\fi{}\ensuremath{\pi}/2.$

Level attraction and level repulsion of magnon coupled with a cavity anti-resonance

We report on coherent and dissipative coupling between a magnon mode and an anti-resonance of transmission in a cylindrical microwave cavity. By effectively suppressing coherent coupling, we observe the hybridized dispersion to change from level repulsion to level attraction. A careful examination reveals distinct differences in the line shape and phase evolution of transmission spectra between these coupling behaviors. For a quantitative understanding of the interactions between the magnon mode and the cavity anti-resonance, we develop a model which precisely describes our experimental observations, particularly, the signature in the line shape and phase of the microwave transmission. Our work sets a foundation for understanding strong coupling between magnon modes and cavity anti-resonances. In addition, it also confirms the ubiquity of level attraction in coupled magnon-photon systems, which may be helpful to develop future magnon-based hybrid quantum systems.

Control of the Magnon-Photon Level Attraction in a Planar Cavity

A resistive coupling circuit is used to model the recently discovered dissipative coupling in a hybridized cavity photon-magnon system. With this model as a basis we have designed a planar cavity in which a controllable transition between level attraction and level repulsion can be achieved. This behaviour can be quantitatively understood using an LCR circuit model with a complex coupling strength. Our work therefore develops and verifies a circuit method to model level repulsion and level attraction and confirms the universality of dissipative coupling in the cavity photon-magnon system. The realization of both coherent and dissipative couplings in a planar cavity may provide new avenues for the design and adaptation of dissipatively coupled systems for practical applications in information processing.

Generation of squeezed states and single-phonon states via homodyne detection and photon subtraction on the filtered output of an optomechanical cavity

In this paper, we consider the generation of mechanical squeezed states and single-phonon Fock states, respectively, by homodyne detection and photon subtraction in a dissipative or dispersive optomechanical system under the situation that the cavity linewidth ${\ensuremath{\kappa}}_{c}$ is much larger than the mechanical frequency ${\ensuremath{\omega}}_{m}$. We at first show that strong mechanical squeezing beyond the 3-dB limit can be achieved by homodyning the filtered cavity output field in a purely dispersive or purely dissipative optomechanical system for ${\ensuremath{\kappa}}_{c}\ensuremath{\gg}{\ensuremath{\omega}}_{m}$, while the combination of the two kinds of coupling can also effectively enhance the mechanical squeezing. We next show that in these optomechanical systems, mechanical single-phonon states with high fidelity can be generated via photon subtraction on the filtered cavity output field in the regimes of weak optomechanical entanglement and ${\ensuremath{\kappa}}_{c}\ensuremath{\gg}{\ensuremath{\omega}}_{m}$. It is found that the single-phonon Fock state via purely dissipative optomechanical coupling is attainable in the blue-detuned regime, whereas it is present in the red-detuned regime by purely dispersive optomechanical coupling. In addition, the effects of thermal fluctuations on the mechanical squeezing and the negativity of the Wigner function of the mechanical single-phonon states are also studied. It is shown that the Gaussian squeezing is much more robust against decohering thermal fluctuations than the non-Gaussian nonclassicality.

An explicit electron-vibron model for olfactory inelastic electron transfer spectroscopy

The vibrational theory of olfaction was posited to explain subtle effects in the sense of smell inexplicable by models in which a molecular structure alone determines an odorant’s smell. Amazingly, behavioral and neurophysiological evidence suggests that humans and some insects can be trained to distinguish isotopologue molecules that are related by the substitution of isotopes for certain atoms, such as a hydrogen-to-deuterium substitution. How is it possible to smell a neutron? The physics of olfaction may explain this isotopomer effect. Inelastic electron transfer spectroscopy (IETS) has been proposed as a candidate mechanism for such subtle olfactory effects: the vibrational spectrum of an appropriately quantized odorant molecule may enhance a transfer rate in the discriminating electron transfer (ET) process. In contrast to other semiclassical or quantum-master-equation-based models of olfactory IETS, the model presented here explicitly treats the dynamics of a dominant odorant vibrational mode, which provides an indirect dissipative path from the electron to the thermal environment. A direct dissipative path to the environment is also included. Within this model, a calculation of the ET rate is developed, along with a calculation of power dissipation to the thermal environment. Under very weak direct dissipative coupling, spectroscopic behaviors of the indirect path are revealed, and the resulting ET rate exhibits resonant peaks at certain odorant frequencies. Resonant peaks in the ET rate also correlate to peaks in power dissipation. Spectroscopic behaviors are masked by strong direct dissipative coupling. Results support a rate-based discrimination between a preferred ligand and an isotopomer if indirect dissipative coupling dominates.

Hermitian and Non-Hermitian Mode Coupling in a Microdisk Resonator Due to Stochastic Surface Roughness Scattering

We make use of a phase-sensitive set-up to study the light transmission through a coupled waveguide-microdisk system. We observe a splitting of the transmission resonance leading to an unbalanced doublet of dips. The experimental data are analyzed by using a phasor diagram that correlates the real and the imaginary parts of the complex transmission. In addition, detailed features are evidenced by a complex inverse representation of the data that maps ideal resonances into straight lines and split resonances into complicated curves. Modeling with finite element method simulations suggests that the splitting and the unbalance is caused by an induced chirality in the propagation of the optical fields in the microdisk due to the interplay between the stochastic roughness and the intermodal dissipative coupling, which yield an asymmetric behavior. An analytical model based on the temporal coupled mode theory shows that both a reactive and a dissipative coupling of the counter-propagating modes by the surface roughness of the ring resonator are required to quantitatively reproduce the experimental observations and the numerical simulations.

Engineering tunable local loss in a synthetic lattice of momentum states

Dissipation can serve as a powerful resource for controlling the behavior of open quantum systems. Recently there has been a surge of interest in the influence of dissipative coupling on large quantum systems and, more specifically, how these processes can influence band topology and phenomena like many-body localization. Here, we explore the engineering of local, tunable dissipation in so-called synthetic lattices, arrays of quantum states that are parametrically coupled in a fashion analogous to quantum tunneling. Considering the specific case of momentum-state lattices, we investigate two distinct mechanisms for engineering controlled loss: one relying on an explicit form of dissipation by spontaneous emission, and another relying on reversible coupling to a large reservoir of unoccupied states. We experimentally implement the latter and demonstrate the ability to tune the local loss coefficient over a large range. The introduction of controlled loss to the synthetic lattice toolbox promises to pave the way for studying the interplay of dissipation with topology, disorder, and interactions.