Weak Pump Research Articles

Tunable fast to slow light and second-order sideband generation in an optomechanical system with phonon pump

We theoretically demonstrate optomechanically induced transparency (OMIT) and its related coherent optical propagation properties such as fast and slow light effects in a cavity optomechanical system driven by a weak coherent phonon pump for suitable parametric and detuning regimes. The probe transmission spectrum experiences different processes under different detuning regimes, and the numerical simulations indicating a tunable and controllable fast-to-slow light propagation can be achieved by controlling the driving amplitudes and phase of the phonon pump. Further, the second-order sideband (SOS) generation is also demonstrated in the system, and it is found that the efficiency of the SOS generation can be significantly enhanced with manipulating the phonon pump in the resonance regime with numerical simulations. More interestingly, the SOS generation is also sensitive to the detuning (the off-resonance regime), and a robust SOS can be induced and the efficiency of the SOS generation even presents mode splitting which is similar to the linear OMIT. These results lead to good tunability of SOS generation and may find applications in manipulation of light propagation.

Observation of Broadband Entanglement in Microwave Radiation from a Single Time-Varying Boundary Condition.

Entangled pairs of microwave photons are commonly produced in the narrow frequency band of a resonator, which represents a modified vacuum density of states. We generate and investigate the entanglement of a stream of photon pairs, generated in a semi-infinite broadband transmission line, terminated by a superconducting quantum interference device (SQUID). A weak pump signal modulates the SQUID inductance, resulting in a single time-varying boundary condition, and we detect all four quadratures of the microwave radiation emitted at two different frequencies separated by 0.7GHz. Power calibration is done insitu, and we find positive logarithmic negativity and two-mode squeezing below the vacuum in the observed radiation, indicating entanglement.

An In-situ and Direct Confirmation of Super-Planckian Thermal Radiation Emitted From a Metallic Photonic-Crystal at Optical Wavelengths

Planck’s law predicts the distribution of radiation energy, color and intensity, emitted from a hot object at thermal equilibrium. The Law also sets the upper limit of radiation intensity, the blackbody limit. Recent experiments reveal that micro-structured tungsten can exhibit significant deviation from the blackbody spectrum. However, whether thermal radiation with weak non-equilibrium pumping can exceed the blackbody limit in the far field remains un-answered experimentally. Here, we compare thermal radiation from a micro-cavity/tungsten photonic crystal (W-PC) and a blackbody, which are both measured from the same sample and also in-situ. We show that thermal radiation can exceed the blackbody limit by >8 times at λ = 1.7 μm resonant wavelength in the far-field. Our observation is consistent with a recent calculation by Wang and John performed for a 2D W-PC filament. This finding is attributed to non-equilibrium excitation of localized surface plasmon resonances coupled to nonlinear oscillators and the propagation of the electromagnetic waves through non-linear Bloch waves of the W-PC structure. This discovery could help create super-intense narrow band thermal light sources and even an infrared emitter with a laser-like input-output characteristic.

Spectral shaping of the biphoton state from multiplexed thermal atomic ensembles

We theoretically investigate the spectral property of a biphoton state from multiplexed thermal atomic ensembles. This biphoton state originates from the cascade emissions, which can be generated by two weak pump fields under four-wave mixing condition. Under this condition, a signal photon from the upper transition, chosen in a telecommunication bandwidth, can be generated along with a correlated idler photon from the lower infrared transition. We can spectrally shape the biphoton state by multiplexing the atomic ensembles with frequency-shifted emissions, where the entropy of entanglement can be analyzed via Schmidt decompositions. We find that this spectral entanglement increases when more vapor cells are multiplexed with correlated or anti-correlated signal and idler fields. The eigenvalues in Schmidt bases approach degenerate under this multiplexing scheme, and corresponding Schmidt numbers can be larger than the number of the multiplexed vapor cells, showing the enlarged entropy of entanglement and excess correlated modes in continuous frequency spaces. We also investigate the lowest entropy of entanglement allowed in the multiplexing scheme, which is preferential for generating a pure single photon source. This shows the potentiality to spectrally shape the biphoton source, where high-capacity spectral modes can be applied in long-distance quantum communication and multimode quantum information processing.

Entanglement versus cooling in the system of a driven pair of two-level qubits longitudinally coupled with a boson-mode field

The relationship between the entanglement creation within coherently pumped and closely spaced two-level emitters longitudinally coupled with a single-mode boson field, and the subsequent quantum cooling of the boson mode are investigated. Even though the two-level qubits are resonantly driven, we have demonstrated an efficient cooling mechanism well below limits imposed by the thermal background. Furthermore, the cooling effect is accompanied by entanglement of the qubit pair components when the dipole–dipole frequency shift is close to the frequency of the boson mode. The maximum boson-mode cooling efficiency is realized at the expense of the entanglement creation. Importantly, this occurs for rather weak external pumping fields protecting the sample from the deterioration. Finally, the conditions to effectively optimize these effects are described as well.

Quasidistribution of phases in Raman process with weak and strong pumps

Nonclassicality is quantified using a quasidistribution of phases for the Raman process under both weak and strong pump conditions. In the former case, the solution is applicable to both resonant and off-resonant Raman processes, while strong classical pump is assumed at resonance. Under weak pump conditions (i.e. in a complete quantum treatment), the phase difference of phases described by single nonclassical modes is required to be filtered to describe a regular distribution function, which is not the case with strong pump. Compound Stokes-phonon mode shows nonclassical features of phases in both weak and strong pumping, which effect is similar to that for compound pump-phonon (Stokes–anti-Stokes) mode with weak (strong) pump. While anti-Stokes-phonon mode is observed to be classical and coherence conserving in strong pump case, pump-Stokes mode shows similar behavior in a special case in quantum treatment.

Spectra of plasmon-exciton composite under weak coherent pumping within cavity QED treatment

The quantum states of plasmon-exciton polariton are generally revealed through its scattering spectra in experiments. Here, we present the exact quantum-electrodynamics results of the spectra of plasmon-exciton composite, considering the multimode features of the plasmonic cavity. Different from a single-mode cavity, we find that the existence of higher-order modes leads to incoherent plasmon-exciton coupling, which saturates the cooperativity as the dipole moment of the quantum emitter (QE) increases. Furthermore, the competition of the coherent and incoherent coupling yields an optimal dipole moment for maximum spectral splitting. Though the higher-order modes are nonradiative, they modify the local dynamics of the QE, which present in the scattering spectra through the interplay between the dipolar plasmonic mode and the QE. We demonstrate that the scattering spectra are dominant by the cavity radiation and essentially different from the spontaneous emission (SE) spectrum. However, we show that the photoluminescence spectra of the QE coincide with its SE spectrum, which is a more reliable way to demonstrate the vacuum Rabi splitting.

Spatiotemporal evolution and spectral character of second harmonic generation in optical microresonator

With the consideration of the second and the third order nonlinear effect, the Lugiato-Lefeve equation which describes the field evolution of the fundamental frequency wave and the second harmonic wave is introduced. Based on the Lugiato-Lefeve equation, the generation of the second harmonic wave in the SiN microresonator is analyzed, and the effect of the each parameter on the dual field is studied. Simulation results indicate that the stable field of the fundamental frequency wave is of flat top pulse, and the field of the second harmonic wave is of sinusoidal distribution. When the detuning parameter increases, the power of the dual wave inside the microresonator oscillates, and the stable power weakens, the stable light field is periodically varied. Moreover, the chaos emerges as detuning parameter becomes large. The stable field can be generated in the microresonator with the weak pump power. However, because of the high pump power, the dispersion and nonlinear effect are enhanced, resulting in the periodic light field. Furthermore, the oscillation of the dual power curve is aggravated, as the pump power increases. In addition, the turning patterns can be observed by choosing the special dimension of microresonator. Theoretical analysis results are significant for studying the generation of the second harmonic wave in the microresonator.

Time-dependent spectral properties of a photoexcited one-dimensional ionic Hubbard model: an exact diagonalization study

Motivated by the recent progress in time-resolved nonequilibrium spectroscopy in condensed matter, we study an optically excited one-dimensional ionic Hubbard model by exact diagonalization. The model is relevant to organic crystals, transition metal oxides, or ultracold atoms in optical lattices. We implement numerical pump-probe measurements to calculate time-dependent conductivity and single-particle spectral functions. In general, short optical excitation induces a metallic behavior imprinted as a Drude peak in conductivity or an in-gap density of states. In a Mott insulator, we find that the induced Drude peak oscillates at the pump frequency and its second harmonic. The former comes from the oscillation of currents, and the latter from the interference of single- and three-photon excited states. In a band insulator, the Drude peak oscillates only at the pump frequency, and quantities such as the double occupancy do not oscillate. The absence of the second harmonic oscillation is due to the degeneracy of multi-photon excited states. The in-gap density of states in both insulators correlates with the Drude weight and the energy absorption for weak pumping. Strong pumping leads to saturation of the in-gap density of states and to suppression of the Drude weight in the Mott regime. We have also checked that the above features are robust for insulators in the intermediate parameter range. Our study demonstrates the distinct natures of the multi-photon excited states in two different insulators.

Threshold photodissociation dynamics of NO2 studied by time-resolved cold target recoil ion momentum spectroscopy.

We study the near-threshold photodissociation dynamics of NO2 by a kinematically complete femtosecond pump-probe scheme using a cold target recoil ion momentum spectrometer. We excite NO2 to the optically bright Ã2B2 state with a 400 nm pulse and probe the ensuing dynamics via strong field single and double ionization with a 25 fs, 800 nm pulse. The pump spectrum spans the NO(X2Π) + O(3P) dissociation channel threshold, and therefore, following internal conversion, excited NO2 is energetically prepared both "above threshold" (dissociating) and "below threshold" (nondissociating). Experimentally, we can clearly discriminate a weak two-photon pump channel from the dominant single-photon data. In the single ionization channel, we observe NO+ fragments with nonzero momentum at 200 fs delay and an increasing yield of NO+ fragments with near-zero momentum at 3.0 ps delay. For double ionization events, we observe a time-varying Coulombic kinetic energy release between the NO+ and O+ fragments impulsively created from the evolving "hot" neutral ground state. Supported by classical trajectory calculations, we assign the decreasing Coulombic kinetic energy release at longer time delays to the increasing average NO-O distances in the ground electronic state during its large amplitude phase space evolution toward free products. The time-resolved kinetic energy release in the double ionization channel probes the large amplitude ground state evolution from a strongly coupled "inner region" to a loosely coupled "outer region" where one O atom is on average much further away from the NO. Both the time evolution of the kinetic energy release and the NO+ angular distributions support our assignments.

Analytical approach to calculate the gain of Brillouin fiber amplifiers in the regime of pump depletion.

We provide an accurate analytic expression for the Brillouin fiber amplifiers (BFAs) gain in the regime of pump depletion. The solutions are divided into three parts. In the first part, we review the weak pump regime where the highly accurate second-order corrected undepleted-pump-approximation-based solution is adopted; in the high-gain regime where both the fiber loss and nonlinear term are nonnegligible effects and need to be accounted for along with the pump depletion; and in the saturation regime where the Stokes power is at the rear end exceeds critical power. We provide an accurate analytic expression for the BFA gain and show results of experimental validation. The presented analysis can be used to accurately predict the performance of Brillouin fiber amplifiers working in any regime.

Study on improving the efficiency of superfluorescent Yb-doped fiber source operating near 980 nm with distributed side-coupled cladding-pumped fiber

Abstract The high-power 980-nm superfluorescent Yb-doped fiber source (SYFS) fabricated with the distributed side-coupled cladding-pumped (DSCCP) fiber is studied with the purpose of improving its efficiency. In experiment, by strengthening the pump light coupling of DSCCP fiber, more-than 23% slope efficiency with the record value of 23-W 980-nm emission is obtained. By means of the numerical study, it is revealed that the 980-nm SYFS efficiency can also be enlarged by optimizing the dopant concentration even with the relatively weak pump coupling, which provides an alternative way to improve the efficiency of SYFS. The pertinent results can be of great importance for studying and designing the 980-nm Yb-doped fiber source.

Photoreaction Dynamics of Red-Shifting Retinal Analogues Reconstituted in Proteorhodopsin.

Microbial rhodopsins constitute a key protein family in optobiotechnological applications such as optogenetics and voltage imaging. Spectral tuning of rhodopsins into the deep-red and near-infrared spectral regions is of great demand in such applications because more bathochromic light into the near-infrared range penetrates deeper in living tissue. Recently, retinal analogues have been successfully used in ion transporting and fluorescent rhodopsins to achieve red-shifted absorption, activity, and emission properties. Understanding their photochemical mechanism is essential for further design of appropriate retinal analogues but is yet only poorly understood for most retinal analogue pigments. Here, we report the photoreaction dynamics of red-shifted analogue pigments of the proton pump proteorhodopsin (PR) containing A2 (all-trans-3,4-dehydroretinal), MOA2 (all-trans-3-methoxy-3,4-dehydroretinal), or DMAR (all-trans-3-dimethylamino-16-nor-1,2,3,4-didehydroretinal), utilizing femto- to submillisecond transient absorption spectroscopy. We found that the A2 analogue photoisomerizes in 1.4, 3.0, and/or 13 ps upon 510 nm light illumination, which is comparable to the native retinal (A1) in PR. On the other hand, the deprotonation of the A2 pigment Schiff base was observed with a dominant time constant of 67 μs, which is significantly slower than the A1 pigment. In the MOA2 pigment, no isomerization or photoproduct formation was detected upon 520 nm excitation, implying that all the excited molecules returned to the initial ground state in 2.0 and 4.2 ps. The DMAR pigment showed very slow excited state dynamics similar to the previously studied MMAR pigment, but only very little photoproduct was formed. The low efficiency of the photoproduct formation likely is the reason why DMAR analogue pigments of PR showed very weak proton pumping activity.

The Regulation of Lymphatic Muscle Cell Contractile Activity by Intracellular Calcium Signals

Lymphedema is characterized by chronic edema due to lymphatic insufficiency. Normally, the spontaneous contractions of the collecting lymphatic vessels (cLVs) function to pump lymph against a pressure gradient back to the blood stream, however cLVs from lymphedema patients often display weak or irregular pumping activity. We have recently shown that that mouse lymphatic muscle cells (LMCs) exhibit a diastolic depolarization that sets contraction frequency and is the basis of cLV pacemaking and autorhythmicity. In murine cLVs, this diastolic depolarization is pressure‐dependent and is mediated by the Ca2+ activated chloride channel Anoctamin1 (Ano1). Ano1 is presumed to be activated by the spontaneous Ca2+ transients originating from the sarcoplasmic reticulum (SR), however the identity of the SR Ca2+ channels underlying these diastolic Ca2+ transients has not been rigorously tested using genetic models. We tested the hypothesis that intracellular Ca2+ signals released from the SR are critical in regulating lymphatic pacemaking and contractile activity. We sorted murine LMCs and observed expression of both Itpr1 and RyR2. We tested the role of Itpr1 and RyR2 in the electrical and contractile regulation of the murine inguinal‐axillary cLV (Ing‐Ax) through the use of inducible deletion models (MYH11CreERT2) or mice harboring knock‐in gain of function (GOF) of loss of function (LOF) mutations. These mouse models include Ano1fl/fl, Itpr1fl/fl, Itpr1DK (GOF mutant), Itpr1DA (LOF mutant), RyR2fl/fl, and RyR2VF (GOF mutant). We performed ex vivo isobaric vessel myography in response to a physiological pressure range to determine Ing‐Ax contraction frequency (Freq), contraction amplitude (Amp), and vessel tone (Tone). In some experiments, we also recorded membrane potential using “sharp electrodes” and imaged Ca2+ signals using the genetically encoded cytosolic Ca2+ sensor GCaMP6f or GCaMP8 from pressurized Ing‐Ax cLVs. Ing‐Ax cLVs isolated from the heterozygous Itpr1DA/WT, the homozygous Itpr1DA/DA, and Itpr1smKO mice had significantly reduced contraction Freq and Tone, but also observed significantly higher Amp. Strikingly, Itpr1smKO Ing‐Ax cLVs also lacked the pressure‐dependent chronotropy similar to cLVs from Ano1smKO mice, however Itpr1smKO vessels had unstable periodicity in the contraction rhythm. Ing‐Ax cLVs from RyR2smKO mice had normal contraction Freq, Amp and Tone. In contrast, Ing‐Ax cLVs from the GOF RyR2VF/KO mice had significantly higher Tone and Freq, but significantly reduced Amp. Ing‐Ax cLVs from GOF Iptr1DK mice contracted into a paralytic rigor during the vessel warming and equilibration period likely due to Ca2+overload. These findings suggest that the pressure‐dependent Freq in murine cLVs is mediated by the activation of Ano1 by SR Ca2+ release through Itpr1 and an acceleration of the diastolic depolarization.Support or Funding InformationR01‐H122578 (MD), R01‐HL133256 & R01‐HL137745 (JJ)This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Bond-distance-dependent Auger decay of core-excited N2 using an ultrashort x-ray pump and continuous-wave IR-control scheme

Resonant Auger spectra (RAS) of core-excited ${\mathrm{N}}_{2}$ are theoretically investigated by implementing an ultrashort x-ray pump and strong continuous-wave (CW) IR-control scheme. A femtosecond weak x-ray pump resonantly excites the nitrogen core-excited $1s\ensuremath{\rightarrow}{\ensuremath{\pi}}^{*}$ of the ${\mathrm{N}}_{2}$ molecule; a strong CW IR control induces dynamic Stark shift of the core-excited level. With the pulse duration of the ultrashort pump comparable to or even shorter than the period of the IR control, the time overlapping between the pump and control pulses reduces into a subcycle of the IR pulse; the efficient pumping process strongly depends on the dynamic Stark shift and the relative phase between the two pulses, resulting in a great manipulation of the core-excited wave-packet dynamics and the subsequent RAS. The results are numerically illustrated for the ${\mathrm{N}}_{2}$ molecule by a 2-fs x-ray pulse. The RAS also show a strong dependence on the bond-distance-dependent Auger decay probability.

Dual-wavelength external-cavity surface-emitting laser

Dual-wavelength laser sources have important applications in the interferometry and the nonlinear-frequency-conversion generated mid-infrared or terahertz-band coherent radiation. Vertical-external-cavity surface-emitting lasers own outstanding advantages such as high output power, good beam quality and flexible emission wavelength, which make them very suitable for dual-wavelength running. In this paper, we employ a collinear Y-type cavity to produce a dual-wavelength laser. There are two semiconductor gain chips in the resonant cavity, one has an active region of In<sub>0.185</sub>Ga<sub>0.815</sub>As/GaAs strained multiple quantum wells and a designed wavelength of 960 nm, and the other has an active region of In<sub>0.26</sub>Ga<sub>0.74</sub>As/GaAsP<sub>0.02</sub> strained multiple quantum wells and a target wavelength of 1080 nm. The peak wavelength of the photoluminescence of chip 1 is 950 nm, which is 10 nm shorter than the designed wavelength under weak pump, and the peak wavelength of the photoluminescence of chip 2 is 1094 nm, which is 14 nm longer than the target wavelength under low pump. When the pump power is increased, the peak wavelengths of the photoluminescence of two gain chips are both red-shifted. The oscillating laser wavelengths are centered at 953 nm and 1100 nm, the corresponding full width at half maximum (FWHM) values of the laser spectra are 1.1 nm and 2.7 nm, respectively. The wavelength spacing of the dual-wavelength is 147 nm, and the related mid-infrared coherent radiation is about 7.1 μm on the assumption that the dual-wavelength laser is used for difference frequency generation. When the absorbed pump power of each gain chip is 5.8 W, the total output power of the dual-wavelength laser reaches 293 mW at room temperature.

Dynamics of a Quantum Emitter Coupled to a Metal Nanostructure in the Presence of External Resonant Field

The relaxation dynamics of a quantum dipole emitter coupled to a metal nanostructure in the presence of an external resonant pump field is studied. It was found that in the mode of weak pumping, the phase of the response from a metallic nanostructure plays a key role in the dynamics of the quantum dipole emitter and allows one to control the fluorescence process. It is shown that when the phase shift is set close to π/2, the quantum emitter makes a quick transition into the ground state, then slowly passes into a superposition state with a small probability to remain in an excited state. Meanwhile, in the case of phase shift values close to 3π/2, the system relaxes into a stationary superposition state where the probability to be in the excited state is close to unity. It was established that the dynamics of the system also depends on the intensity of the external field and with the amplification of the latter, the system enters into the mode of the asymmetric Rabi oscillations.

Parity‐Time‐Symmetric Optical Lattice with Alternating Gain and Loss Atomic Configurations

AbstractSince the periodic parity‐time (PT)‐symmetric potential can possess unique properties compared to a single PT cell (with only two coupled components), various schemes have been proposed to realize PT symmetry in optical lattices. Here, a PT‐symmetric optical lattice is experimentally constructed with simultaneous gain and loss in an atomic medium. The gain and loss arrays are created in the four‐level N‐type configurations excited by spatially alternating strong and weak pump fields, respectively, which do not require discrete diffractions and can be realized more easily with more relaxed operating conditions. Also, the gain and loss coefficients can be modified independently. The dynamical behaviors of the system are investigated by measuring the phase difference between two adjacent gain and loss channels. The demonstrated PT‐symmetric lattice with easy accessibility and better tunability shows obvious advantages in exploiting more peculiar properties and great improvements in practical applications of periodic PT‐symmetric potentials.

Quantum photonics model for nonclassical light generation using integrated nanoplasmonic cavity-emitter systems

The implementation of non-classical light sources is becoming increasingly important for various quantum applications. A particularly interesting approach is to integrate such functionalities on a single chip as this could pave the way towards fully scalable quantum photonic devices. Several approaches using dielectric systems have been investigated in the past. However, it is still not understood how on-chip nanoplasmonic antennas, interacting with a single quantum emitter, affect the quantum statistics of photons reflected or transmitted in the guided mode of a waveguide. Here we investigate a quantum photonic platform consisting of an evanescently coupled nanoplasmonic cavity-emitter system and discuss the requirements for non-classical light generation. We develop an analytical model that incorporates quenching due to the nanoplasmonic cavity to predict the quantum statistics of the transmitted and reflected guided waveguide light under weak coherent pumping. The analytical predictions match numerical simulations based on a master equation approach. It is moreover shown that for resonant excitation the degree of anti-bunching in transmission is maximized for an optimal cavity modal volume $V_{c}$ and cavity-emitter distance $s$. In reflection, perfectly anti-bunched light can only be obtained for specific $(V_{c},s)$ combinations. Finally, our model also applies to dielectric cavities and as such can guide future efforts in the design and development of on-chip non-classical light sources using dielectric and nanoplasmonic cavity-emitter systems.

ASSESSMENT OF CARDIAC HEART FAILURE AND CARDIAC ARTERY DISEASE BY THE HIGHER ORDER SPECTRA

Cardiac diseases are major reason of death in the world populace and the numeral of cases is upsurging every year. Due to cardiac artery disease (CAD), the strength of heart muscles becomes weak and heart pumping is disturbed which may eventually lead to abnormal heart beat and heart failure. Therefore, the beginning stage detection of CAD and cardiac heart failure (CHF) are of prime importance. In this work, we have used a non-invasive diagnosis method as higher order spectra (HOS) for assessment of cardiac diseases. The method indicates whether or not a cardiac heart disease is present, by assessing the cardiac health of subjects using extracted features from heart rate variability (HRV) signals. This assessment is based on 10 spectra nonlinear features. These features were extracted from HRV signals by using the HOS method. For this study, the R-R interval data (i.e. HRV signals) were taken from the standard database of cardiac heart failure (CHF), CAD patients, healthy young (YNG) and Self recorded of healthy young (SELF_YNG) subjects. Statistical assessments were performed on the group of database sets as YNG-CAD, YNG-CHF, SELF_YNG-CAD and Self_YNG-CHF subjects. A Wilcoxon rank sum test ([Formula: see text]-value) was used to statistically compare the features extracted by HOS for group of data sets. It indicates whether or not the same features of individual classes of HRV data sets are dissimilar. The results depicted that the all features are very significant ([Formula: see text]) except the phase entropy (PHE) feature which is not significant for CAD-CHF, SELF_YNG-CAD and SELF_YNG-CHF group of subjects. While in the case of YNG-CAD group of subjects, features like first-order spectral moment of amplitudes of diagonal elements (H3), PHE and logarithmic amplitudes of diagonal elements (H2) are significant ([Formula: see text]) and excluding these features, the remaining features are very significant except MM and H1 which are not significant. The results also depicted that the mean value of sum of logarithmic amplitude (H1), H2, normalized entropy (P1), normalized squared entropy (P2) and PHE features of healthy YNG subjects are having higher values than that of CAD and CHF patients. While weighted center of bi-spectrum (WCOB2) and FLAT spectrum features are lower than CAD and CHF patients compared to YNG subjects. In case of CAD and CHF patients, all the features of CAD patients are having higher values compared to CHF except P1, P2 and WCOB1.