Coherence Resonance Research Articles

Stochastic generation and suppression of early afterdepolarizations in a three‐dimensional model of cardiac action potential

The influence of random disturbances on a three‐dimensional simplification of Luo–Rudy model of the cardiac action potential is studied. We show that in the parameter region, where the deterministic model is in the equilibrium regime, noise can trigger large‐amplitude oscillations that correspond with pathological early afterdepolarizations (EADs). For this stochastic excitement, the phenomenon of coherence resonance was discovered. On the contrary, in another parameter zone of the model, noise can suppress EADs. We analyze these stochastic phenomena using the stochastic sensitivity functions technique, Mahalanobis distance, the methods of principal directions, and confidence domains.

Coherence Resonance in Random Erdös-Rényi Neural Networks: Mean-Field Theory

Additive noise is known to tune the stability of nonlinear systems. Using a network of two randomly connected interacting excitatory and inhibitory neural populations driven by additive noise, we derive a closed mean-field representation that captures the global network dynamics. Building on the spectral properties of Erdös-Rényi networks, mean-field dynamics are obtained via a projection of the network dynamics onto the random network’s principal eigenmode. We consider Gaussian zero-mean and Poisson-like noise stimuli to excitatory neurons and show that these noise types induce coherence resonance. Specifically, the stochastic stimulation induces coherent stochastic oscillations in the γ-frequency range at intermediate noise intensity. We further show that this is valid for both global stimulation and partial stimulation, i.e. whenever a subset of excitatory neurons is stimulated only. The mean-field dynamics exposes the coherence resonance dynamics in the γ-range by a transition from a stable non-oscillatory equilibrium to an oscillatory equilibrium via a saddle-node bifurcation. We evaluate the transition between non-coherent and coherent state by various power spectra, Spike Field Coherence and information-theoretic measures.

Controlled Coherence Plasmonic Light Sources

Through a computational model, we study the coherence converting capabilities of an array of holes in a surface plasmon-supporting metal plate, with an eye towards the creation of controlled coherence plasmonic light sources. We evaluate how the average coherence and transmission of the hole array depends on the parameters of the array, such as the array geometry, lattice constant, and hole size. We show that the location of coherence bandgaps and resonances can be estimated through a simple formula and that increases in coherence are strongly correlated with increases in transmission.

A minimal model for synaptic integration in simple neurons

Synaptic integration is a prominent aspect of neuronal information processing. The detailed mechanisms that modulate synaptic inputs determine the computational properties of any given neuron. We study a simple model for the summation of excitatory inputs from synapses and illustrate its use by characterizing some functional properties of postsynaptic neurons. In this regard, we study the response of postsynaptic neurons as defined by the model to two well known noise driven processes: stochastic and coherence resonance. The model requires a small number of parameters and is especially useful to isolate the role of integration mechanisms that rely on summation of inputs with little dendritic processing.

High-temperature lithium atomic magnetometry by symmetric hyperfine coherent population trapping resonances

A glass lithium vapor cell is an atomic sensor operating at high temperature. The longitudinal magnetic-field strength is measured by coherent population trapping (CPT) in ground-state hyperfine levels. Two linearly polarized light beams are polarized orthogonally to each other. The difference of optical frequencies is tuned to generate a dark state. Additionally, a few light modes of equidistant frequency spacing are generated by modulating the difference frequency. The symmetry of the light modes and the energy levels enables simultaneous measurement of the hyperfine splitting frequency of the ground state and the magnetic-field strength. Tuning the optical frequency difference to the central CPT resonance, a sensitivity of 15 p T / H z is achieved. The time response and the sensitivity of the CPT magnetometry are studied by changing the cell temperature, the laser power, the frequency separation of the light modes, and the Zeeman frequency.

Arousal Fluctuations Govern Oscillatory Transitions Between Dominant [Formula: see text] and [Formula: see text] Occipital Activity During Eyes Open/Closed Conditions.

Arousal results in widespread activation of brain areas to increase their response in task and behavior relevant ways. Mediated by the Ascending Reticular Arousal System (ARAS), arousal-dependent inputs interact with neural circuitry to shape their dynamics. In the occipital cortex, such inputs may trigger shifts between dominant oscillations, where [Formula: see text] activity is replaced by [Formula: see text] activity, or vice versa. A salient example of this are spectral power alternations observed while eyes are opened and/or closed. These transitions closely follow fluctuations in arousal, suggesting a common origin. To better understand the mechanisms at play, we developed and analyzed a computational model composed of two modules: a thalamocortical feedback circuit coupled with a superficial cortical network. Upon activation by noise-like inputs originating from the ARAS, our model is able to demonstrate that noise-driven non-linear interactions mediate transitions in dominant peak frequency, resulting in the simultaneous suppression of [Formula: see text] limit cycle activity and the emergence of [Formula: see text] oscillations through coherence resonance. Reduction in input provoked the reverse effect - leading to anticorrelated transitions between [Formula: see text] and [Formula: see text] power. Taken together, these results shed a new light on how arousal shapes oscillatory brain activity.

Topologically optimized periodic resonant nanostructures for extraordinary optical transmission [Invited

This paper presents the inverse design of resonant nanostructures for extraordinary optical transmission of periodic metallic slits, where the topology optimization approach is utilized to implement the inverse design procedure and find the geometrical configurations of the nanostructures. By using the inverse design method, the subwavelength-sized resonant nanostructures, localized at the inlet and outlet sides of the periodic metallic slits, are derived with transmission peaks at the prescribed incident wavelengths. The transmissivity is enhanced by effective excitation and guidance of surface plasmon polariton at the inlet side of the slits, the coherent resonance of surface plasmon polariton inside the slits, and radiation of the photonic energy at the outlet side of the slits. The transmission peaks of the periodic metallic slits, with inversely designed resonant nanostructures, are raised along with the red shift of the incident wavelength. The position of the transmission peak of periodic metallic slits can be controlled and localized at the desired frequency, by specifying the incident wave with the wavelength corresponding to the desired frequency preset in the inverse design procedure. By maximizing the minimum transmissivity of the periodic metallic slits with incident wavelengths in a prescribed wavelength range, the extraordinary optical transmission bandwidth can be enlarged, and the sensitivity of transmissivity to wavelength can be decreased equivalently.

Effect of the Motion of Atoms and Collisions with the Antirelaxation Coating of the Walls of Gas Cells on the Shape and Shift of the Coherent Population Trapping Resonance

Effect of the Motion of Atoms and Collisions with the Antirelaxation Coating of the Walls of Gas Cells on the Shape and Shift of the Coherent Population Trapping Resonance

Harvesting wind energy with a bi-stable configuration integrating vortex-induced vibration and galloping

This paper proposed a wind energy harvester that integrates the merits of vortex-induced vibration (VIV), galloping and multi-stability. Two different shapes of bluff bodies are introduced to induce VIV and galloping for incoming flow, respectively. Three magnets are placed on the beam and fixture so as to generate bi-stability by magnetic attraction. As the wind blows through, the induced aero-dynamical instability leads the piezoelectric beam to oscillate and execute snap-through motion, which could generate a large electric output. The validation experiment was conducted. The experimental results show that as the flow speed increases from v= 1.0 m s−1 to 7.0 m s−1, the harvester could begin snap-through motion from a low speed v = 1.5 m s−1, and maintain the coherence resonance motion within a broad range of wind speed. Thus, it could maintain the large output in the environment of variable-speed wind.

Reflection-type vapor cell for micro atomic clocks using local anodic bonding of 45° mirrors.

This Letter reports the design, fabrication, and evaluation of reflection-type planar vapor cells for chip-scale atomic clocks. The cell with 2-8 mm cavity length contains two 45° Bragg reflector mirrors assembled using a local anodic bonding. Coherent population trapping resonance of Rb atoms is observed, realizing an atomic clock operation. Allan deviations at an averaging time of 1 s are ${2.2} \times {{1}}{{{0}}^{- 10}}$ and ${9.5} \times {{1}}{{{0}}^{- 11}}$ for 2 mm long and 6 mm long vapor cells, respectively. These results show that planar vapor cells compatible with a system-in-package are feasible without degradation of clock stabilities compared to conventional vertically stacked cells.

Ultrathin Muffler with Coherent Coupling Weak Resonance for HVDC Converter Station Medium Frequency Band Noise Control

HVDC converter station noise is mainly in medium frequency band, but the thickness of the conventional duct silencers are equivalent to the working wavelength, which makes them difficult to apply in narrow spaces. In this paper, through parallel and serial coupling of imperfect Helmholtz resonators with interpolated neck, a hybrid silencer with broadband perfect absorption is presented, which remain above 10 dB from 568 to 992 Hz with a thickness less than 20mm. In order to reveal the underlying physical properties and acoustic performance, simulations considering the coupling of acoustics and thermodynamics and impedance analysis are performed, showing a good consistency, and it’s further verified by experimental result. The results of research can help design effectively, ultra-thin and wide-band duct silencer for HVDC converter station medium frequency band noise control.

Polarization asymmetry of the dark-resonance frequency dependence on the magnetic field

We demonstrate the possibility of suppressing the linear response of the coherent population trapping resonance frequency to variations in the external magnetic field. The suppression can be achieved at a specific value of the clock magnetic field B due to the competition between the frequency pulling by neighboring resonances and the quadratic Zeeman shift. The effect is possible only with certain combinations of the optical field polarization and the direction of the magnetic field. An incorrect field configuration can significantly increase the magnetic-induced frequency shifts.

Coherent single-spin electron resonance spectroscopy manifested at an exceptional-point singularity in doped polyacetylene

Spin-dependent charge-transfer decay in an alkali atom-doped polyacetylene is studied in terms of the complex spectral analysis, revealing the single-spin Zeeman splitting influenced by the spin-orbit interaction. A non-Hermitian effective Hamiltonian has been derived from the total system Hermitian Hamiltonian using the Brillouin-Wigner-Feshbach projection method where the microscopic spin-dependent dissipation effect is correctly incorporated in the energy-dependent self-energy. Since the present method maintains the dynamical and chiral symmetries of the total system, we discovered two types of exceptional point (EP) singularities: The EP surface and the EP ring are attributed to the dynamical and chiral symmetry breaking, respectively. We reveal that the coherent single-spin electron resonance (SSESR) spectrum reflects the complex eigenenergy spectrum of the system. We formulate the SSESR spectrum in terms of the non-linear-response function in the Liouville-space pathway approach where we have constructed the Liouville-space basis using the complex eigenstates of the total Hamiltonian. We calculate the one-dimensional Fourier transform (1DFT) and two-dimensional Fourier transform (2DFT) SSESR spectra reflecting the spin-relaxation dynamics at the donor site. Whereas the 1DFT SSESR spectrum reflects the complex eigenenergy spectrum, the 2DFT gives detailed information about the quantum coherence in the spin-relaxation dynamics as a cross correlation between the two frequencies. We reveal a giant response in the coherent SSESR around the EP ring singularity due to the vanishing normalization factors at the EP ring and the resonance effect. We show this giant response is even more heavily pronounced in the 2DFT spectrum than in the 1DFT spectrum, which illustrates that the 2DFT SSESR can become a useful tool to observe the single-spin response of a molecule.

Stochastic dynamic behavior of FitzHugh–Nagumo neurons stimulated by white noise

Stochastic noise exists widely in the nervous system, and noise plays an extremely important role in the information processing of the nervous system. Noise can enhance the ability of neurons to process information as well as decrease it. For the dynamic behavior of stochastic resonance and coherent resonance shown by neurons under the action of stochastic noise, this paper uses Fourier coefficient and coherence resonance coefficient to measure the behavior of stochastic resonance and coherence resonance, respectively, and some conclusions are drawn by analyzing the effects of additive noise and multiplicative noise. Appropriate noise can make the nonlinear system exhibit stochastic resonance behavior and enhance the detection ability of external signals. It can also make the coherent resonance behavior of the nonlinear system reach its optimal state, and the system becomes more orderly. By comparing the effects of additive and multiplicative noise on the stochastic resonance behavior and coherent resonance behavior of the system, it is found that additive and multiplicative noise can both make the system appear the phenomenon of stochastic resonance and have almost identical discharge state at the same noise intensity. However, with the increase of noise intensity, the coherent resonance of the system occurs, the multiplicative noise intensity is smaller than that of additive noise, but the coherent resonance coefficient of additive noise is smaller and the coherent resonance effect is better. The system whose system parameters are located near the bifurcation point is more prone to coherent resonance, and the closer the bifurcation point is, the more obvious the coherent resonance phenomenon is, and the more regular the system becomes. When the parameters of the system are far away from the bifurcation point, the coherent resonance will hardly appear. Besides, when additive and multiplicative noise interact together, the stochastic resonance and coherent resonance phenomena are more likely to appear at small noise, and the behavior of stochastic resonance and coherent resonance that the system shown is better in the local range.

Quantum coherence resonance

It is shown that coherence resonance, a phenomenon in which regularity of noise-induced oscillations in nonlinear excitable systems is maximized at a certain optimal noise intensity, can be observed in quantum dissipative systems. We analyze a quantum van der Pol system subjected to squeezing, which exhibits bistable excitability in the classical limit, by numerical simulations of the quantum master equation. We first demonstrate that quantum coherence resonance occurs in the semiclassical regime, namely, the regularity of the system’s oscillatory response is maximized at an optimal intensity of quantum fluctuations, and interpret this phenomenon by analogy with classical noisy excitable systems using semiclassical stochastic differential equations. This resonance persists under moderately strong quantum fluctuations for which the semiclassical description is invalid. Moreover, we investigate even stronger quantum regimes and demonstrate that the regularity of the system’s response can exhibit the second peak as the intensity of the quantum fluctuations is further increased. We show that this second peak of resonance is a strong quantum effect that cannot be interpreted by a semiclassical picture, in which only a few energy states participate in the system dynamics.

Enhancement of coherence resonance induced by inhibitory autapse in Hodgkin–Huxley model

Inhibitory effect often suppresses electronic activities of the nervous system. In this paper, the inhibitory autapse is identified to enhance the degree of coherence resonance (CR) induced by noise in the Hodgkin–Huxley (HH) model with Hopf bifurcation from resting state to spiking with nearly fixed period [Formula: see text]. Without noise, the inhibitory autapse can induce a post inhibitory rebound (PIR) spike from the resting state at time delay approximating [Formula: see text] and can inhibit a spike of spiking at time delay approximating [Formula: see text]. In the presence of noise, CR characterized by maximal value of power spectrum of spike trains appears in a wide range of both time delay and conductance of autapse. With increasing autaptic conductance, CR degree becomes stronger for time delay approximating [Formula: see text] plus integer (from 0) multiples of [Formula: see text], because the inhibitory autaptic current pulses can induce more PIR spikes. The decrease of CR degree at time delay approximating integer (from 1) multiples of [Formula: see text] can be explained by the inhibition effect. The promotion of coherence resonance degree and the underlying PIR mechanism induced by inhibitory self-feedback extends the paradoxical phenomenon of inhibitory autapse to stochastic system and presents potential measures to modulate CR degree and information processing.

Coherence resonance in neuronal populations: Mean-field versus network model.

The counterintuitive phenomenon of coherence resonance describes a nonmonotonic behavior of the regularity of noise-induced oscillations in the excitable regime, leading to an optimal response in terms of regularity of the excited oscillations for an intermediate noise intensity. We study this phenomenon in populations of FitzHugh-Nagumo (FHN) neurons with different coupling architectures. For networks of FHN systems in an excitable regime, coherence resonance has been previously analyzed numerically. Here we focus on an analytical approach studying the mean-field limits of the globally and locally coupled populations. The mean-field limit refers to an averaged behavior of a complex network as the number of elements goes to infinity. We apply the mean-field approach to the globally coupled FHN network. Further, we derive a mean-field limit approximating the locally coupled FHN network with low noise intensities. We study the effects of the coupling strength and noise intensity on coherence resonance for both the network and the mean-field models. We compare the results of the mean-field and network frameworks and find good agreement in the globally coupled case, where the correspondence between the two approaches is sufficiently good to capture the emergence of coherence resonance, as well as of anticoherence resonance.

The probability density function of interspike intervals in an FHN model with α-stable noise

In this paper, we expand the paradigmatic Fitzhugh–Nagumo (FHN) model by including α-stable noise and study the firing rate and coherence resonance via probability density function (PDF) of the interspike intervals (ISIs). In the previous work, different indicators and measurements are given to illustrate the firing rate and coherence resonance. However, we find that they can be described simply by the PDF of ISIs, which contains the underlying information of spiking neuron signals. For example, the width of the peak of the PDF of ISIs can characterize the phenomenon of coherence resonance. The narrower width of peak stands for the better coherence resonance.

Quantum router modulated by two Rydberg atoms in a X-shaped coupled cavity array

We theoretically investigate the single-photon router using two Rydberg atoms embedded in a multi-channel coupled cavity arrays(CCAs) driven by a classical field. It is shown that when the Rydberg interaction is in the proper range, three kinds of photons with different frequencies are absorbed and the quantum routing can be achieved due to the spontaneous emission of the formed dressed states. The Rydberg interaction can also cause photons that are not originally in the energy range to be routed. Furthermore, the total reflection of the single photon is obtained because of the coherent resonance and the existence of the photonic bound states. Based on these characteristics, it is a feasible scheme to generate a multi-frequency photons router and it could be useful for designing the single-photon devices.

Control of coherence resonance in multiplex neural networks

We study the dynamics of two neuronal populations weakly and mutually coupled in a multiplexed ring configuration. We simulate the neuronal activity with the stochastic FitzHugh-Nagumo (FHN) model. The two neuronal populations perceive different levels of noise: one population exhibits spiking activity induced by supra-threshold noise (layer 1), while the other population is silent in the absence of inter-layer coupling because its own level of noise is sub-threshold (layer 2). We find that, for appropriate levels of noise in layer 1, weak inter-layer coupling can induce coherence resonance (CR), anti-coherence resonance (ACR) and inverse stochastic resonance (ISR) in layer 2. We also find that a small number of randomly distributed inter-layer links are sufficient to induce these phenomena in layer 2. Our results hold for small and large neuronal populations.