arXiv subjects

Evgeny S. Andrianov

Publications and source records attributed to Evgeny S. Andrianov.

At least 19 recordsLinked to original sources

arXiv2026

The influence of strong coupling between single-photon source and spectral filter on photon statistics

One of the most common approaches for coupling optical single-photon sources and photonic integrated circuits is to use a cavity. The cavity acts as a spectral filter that distorts the light spectrum and changes its statistical properties. But in the general case one should take into account not only spectral filtering of light but also the spectral filter influence on the single-photon source dynamics. We build an effective analytical model for description of the cavity influence on the photon statistics of light emitted by the single-photon source as spectral filtering only. We show that this model correctly describes the photon statistics even in a strong-coupling regime between the single-photon source and the spectral filter. Our results can be useful for analytical modeling of photon statistics of quantum emitters strongly coupled to various electromagnetic interfaces.

quant-ph↗

arXiv2026

Stokes-anti-Stokes correlations of light propagating through weakly guiding optical fiber

Statistical properties of light produced in spontaneous Raman scattering on an ensemble of molecules indicate the quantum nature of this phenomenon. The scattered light is non-classical and has high non-classical intensity correlations between Stokes and anti-Stokes components. The temporal coherence of this light is well investigated, while many questions related to spatial coherence remain open. Recent experiments reveal two peculiar features of the spatial coherence of the Stokes and anti-Stokes light. First, the intensity correlations between Stokes and anti-Stokes light remain non-classical even for macroscopic samples containing many molecules. Second, these correlations decrease when signal propagates through a multi-mode optical fiber: the more propagating fiber modes at Stokes and anti-Stokes frequencies the less the correlations. Moreover, the second-order autocorrelation function of Stokes and anti-Stokes light also decreases with the number of propagating modes in multi-mode fiber. In this paper, we build a model of spontaneous Raman scattering correlations of light produced by an ensemble of molecules and propagating through weakly guiding optical fiber that quantitatively explains all these observations. We show that spacial orthogonality of the fiber modes makes the light propagating through these modes uncorrelated in the standard detection scheme. This leads to suppression of non-classical intensity correlations of the total field in the multi-mode fiber. We find the degree of non-classical correlations on fiber parameters. The obtained results pave the way for engineering of non-classical Stokes -- anti-Stokes correlations.

physics.optics↗

arXiv2026

Static SERS with near-minus-one-epsilon substrate

A mechanism for additional enhancement of SERS in the nanoparticle-on-mirror scheme is proposed. This new mechanism is based on the use of a substrate made of material with a near-minus-one permittivity. The setup involves a plasmonic nanoparticle in the form of an oblate ellipsoid positioned above the substrate and a Raman-active molecule located between them. In the conventional nanoparticle-on-mirror scheme, the plasmonic dipole resonance frequency coincides with the Stokes frequency of the Raman-active molecule. Consequently, due to the Purcell effect, the molecule's near fields mostly excites a dipole mode in nanoparticle. This dipole moment is many times greater than the dipole moment of the molecule by itself. If the real part of substrate permittivity is near minus one, the image of the nanoparticle dipole moment in the mirror-substrate is a dipole moment pointed in the same direction but approximately $ 1/{\rm{Im}} \varepsilon_{_{\rm{ENZ}}}$ times larger in magnitude. The simultaneous radiation of these two dipoles additionally increases the SERS intensity in $ 10^4$ times.

physics.optics↗

arXiv2026

Cascade Brilloiun scattering on short-lived phonons for frequency comb generation

We consider Brillouin scattering on short-lived phonon modes, such that the relative Brillouin shift between propagating and scattered waves is smaller than the relative width of phonon modes. In this case one phonon mode facilitates scattering between many pairs of optical modes. We show that in this limit two phonon modes are sufficient for cascade Brillouin scattering (one forward propagating wave and one counter propagating wave), and that the cascade behavior is qualitatively different from the cascade in conventional Brillouin systems with distinct phonon modes for each optical mode pair. In particular, our results show that there is a pump threshold above which many optical modes become excited simultaneously, as opposed to a cascade gradually building up. The resulting cascade scattering can be exploited for frequency comb generation with uniform amplitudes and without the need for anomalous dispersion in the medium.

physics.optics↗

arXiv2025

Exceptional points of arbitrary high orders induced by non-Markovian dynamics

Exceptional points are singularities in the spectrum of non-Hermitian systems in which several eigenvectors are linearly dependent and their eigenvalues are equal to each other. Usually it is assumed that the order of the exceptional point is limited by the number of degrees of freedom of a non-Hermitian system. In this letter, we refute this common opinion and show that non-Markovian effects can lead to dynamics characteristic of systems with exceptional points of higher orders than the number of degrees of freedom in the system. This takes place when the energy returns from reservoir to the system such that the dynamics of the system are divided into intervals in which it describes by the product of the exponential and a polynomial function of ever-increasing order. We demonstrate that by choosing the observation time, it is possible to observe exceptional points of arbitrary high orders.

quant-ph↗

arXiv2025

A control of threshold of hard excitaion mode of optomechanical system by a low-intensity seed wave

An optomechanical system based on two optical modes, one of which is pumped by a coherent wave, interacting with each other via a phonon mode is considered. In such a system, a hard excitation mode can be realized in the region of bistability. It is demonstrated that excitation of an optical mode with a lower frequency by a low-intensity seed wave can lead to a significant reduction of a threshold of the hard excitation mode. This decrease is due to the fact that the seed wave changes the stability of solutions in the bistability region. This leads to the fact that switching from a non-generating state to a generating one occurs at lower values of the intensity of the pump wave. The obtained result paves the way for the creation of all-optical transistors and logical elements.

quant-ph↗

arXiv2025

The influence of shot noise on the performance of phase singularity-based refractometric sensors

Topological singularities of optical response functions -- such as reflection amplitudes -- enable elegant practical applications ranging from analog signal processing to novel molecular sensing approaches. A phase singularity-based refractometric sensor monitors the rapidly evolving argument of the optical field near the point of phase singularity, in contrast to the reflection zero in traditional surface plasmon polariton sensors. This raises a natural question: What happens with the sensitivity and resolution of such a sensor when it operates close to a zero of the response function, where the detected signal may be greatly influenced by various noise sources? In this paper, we systematically study the effect of the shot noise on the performance of a generic phase singularity-based refractometric sensor. We develop a theoretical model of a spectroscopic ellipsometry-based system operating near a phase singularity and couple the macroscopic optical picture of the detection with a quantum shot noise model. Within the developed model, we illustrate how the shot noise of the detector comes into play and study its effect on the sensitivity and resolution of the refractometric sensor. Our results suggest that such an ellipsometry-based phase singularity sensor remains stable even in the presence of shot noise near the point of zero reflection.

physics.optics↗

arXiv2025

Thermalization in Quantum Fluids of Light: A Convection-Diffusion Equation

We develop a microscopic theory for the dynamics of quantum fluids of light, deriving an effective kinetic equation in momentum space that takes the form of the convection-diffusion equation. In the particular case of two-dimensional systems with parabolic dispersion, it reduces to the Bateman--Burgers equation. The hydrodynamic analogy unifies nonlinear wave phenomena, such as shock wave formation and turbulence, with non-equilibrium Bose--Einstein condensation of photons and polaritons in optical cavities. We introduce the Reynolds number $(\textit{Re})$ and demonstrate that the condensation threshold corresponds exactly to a critical Reynolds number of unity $(\textit{Re}=1)$, beyond which $(\textit{Re} > 1)$ a shock-like front emerges in the momentum space, characterized by the Bose--Einstein distribution for the particle density in states with high momentum.

cond-mat.quant-gas↗

arXiv2024

Room-temperature optomechanics with light-matter condensates

In this work, we develop an optomechanical formalism for macroscopic quantum states in exciton-polariton systems with strong exciton-phonon interactions. We show that polariton optomechanical interactions induce dynamical backaction, resulting in dispersive and dissipative shifts in the complex vibrational response functions. Unlike conventional optomechanical systems, polariton optomechanics features high-dimensionality and phase-space confinement due to the dispersion relations of exciton-polaritons. Consequently, vibrational modes exhibit effective positive or negative mass depending on the detuning parameter, and are capable for the nonequilibrium vibrational Bose-Einstein condensation under the resonant conditions [arXiv:2309.08498]. We demonstrate the potential for vibrational control of polariton condensates at room temperature.

cond-mat.quant-gas↗

arXiv2024

Sympathetic Mechanism for Vibrational Condensation Enabled by Polariton Optomechanical Interaction

We demonstrate a macro-coherent regime in exciton-polariton systems, where nonequilibrium polariton Bose--Einstein condensation coexists with macroscopically occupied vibrational states. Strong exciton-vibration coupling induces an effective optomechanical interaction between cavity polaritons and vibrational degrees of freedom of molecules, leading to vibrational amplification in a resonant blue-detuned configuration. This interaction provide a sympathetic mechanism to achieve vibrational condensation with potential applications in cavity-controlled chemistry, nonlinear and quantum optics.

cond-mat.quant-gas↗

arXiv2024

Thermalization rate of polaritons in strongly-coupled molecular systems

Polariton thermalization is a key process in achieving light-matter Bose--Einstein condensation, spanning from solid-state semiconductor microcavities at cryogenic temperatures to surface plasmon nanocavities with molecules at room temperature. Originated from the matter component of polariton states, the microscopic mechanisms of thermalization are closely tied to specific material properties. In this work, we investigate polariton thermalization in strongly-coupled molecular systems. We develop a microscopic theory addressing polariton thermalization through electron-phonon interactions (known as exciton-vibration coupling) with low-energy molecular vibrations. This theory presents a simple analytical method to calculate the temperature-dependent polariton thermalization rate, utilizing experimentally accessible spectral properties of bare molecules, such as the Stokes shift and temperature-dependent linewidth of photoluminescence, in conjunction with well-known parameters of optical cavities. Our findings demonstrate qualitative agreement with recent experimental reports of nonequilibrium polariton condensation in both ground and excited states, and explain the thermalization bottleneck effect observed at low temperatures. This study showcases the significance of vibrational degrees of freedom in polariton condensation and offers practical guidance for future experiments, including the selection of suitable material systems and cavity designs.

quant-ph↗

arXiv2023

Hard excitation mode of system with optomechanical instability

System with strong photon-phonon interaction and optomechanical instability are perspective for generation of coherent phonons and photons. Typically, above the threshold of optomechanical instability, the photon intensity increases linearly with pumping. We demonstrate that in such systems, it is possible to achieve hard mode of excitation when jump increase in the photon intensity takes place. We derive the analytical expression determining conditions for such a jump increase. We demonstrate that the hard excitation mode in system with optomechanical instability arises due to an additional phase condition for the existence of a nonzero solution. The discovered hard excitation mode paves the way for creation highly sensitive sensors and optical transistors.

quant-ph↗

arXiv2023

Adjoint master equation for multi-time correlators

The quantum regression theorem is a powerful tool for calculating the muli-time correlators of operators of open quantum systems which dynamics can be described in Markovian approximation. It enables to obtain the closed system of equation for the multi-time correlators. However, the scope of the quantum regression theorem is limited by a particular time order of the operators in multi-time correlators and does not include out-of-time-ordered correlators. In this work, we obtain an adjoint master equation for multi-time correlators that is applicable to out-of-time-ordered correlators. We show that this equation can be derived for various approaches to description of the dynamics of open quantum systems, such as the global or local approach. We show that the adjoint master equation for multi-time correlators is self-consistent. Namely, the final equation does not depend on how the operators are grouped inside the correlator, and it coincides with the quantum regression theorem for the particular time ordering of the operators.

quant-ph↗

arXiv2022

Controlling Purity, Indistinguishability and Quantum Yield of Incoherently Pumped Two-Level System by Spectral Filters

Dephasing processes significantly impact the performance of deterministic single-photon sources. Dephasing broadens the spectral line and suppresses the indistinguishability of the emitted photons, which is undesirable for many applications, primarily for quantum computing. We consider a light emitted by a two-level system with a pulsed incoherent pump in the presence of the spectral filter. The spectral filter allows control of the second-order autocorrelation function, indistinguishability, and quantum yield. We show that narrow spectral filters can increase the indistinguishability of the emitted light while undermining the quantum yield. The influence of the spectral filter on the second-order correlation function depends on the duration of the pump. When the pumping pulse is long compared to the lifetime of the two-level system, the narrow spectral filters lead to a rapid increase in the second-order autocorrelation function. In this limit, the statistics of the light from the two-level system inherit the statistics of the incoherent pump. In the case of the short duration of the pump pulse, it is possible to preserve single-photon properties to some degree for the sub-lifetime width of the spectral filter. Moreover, when the light emitted by the single-photon source is used to control a quantum system, e.g., cavity, the single-photon properties of the light manifest themselves differently, depending on the response time of the quantum system. In particular, in the case of long response time, the spectral filter with sub-lifetime width can provide the near-zero second-order autocorrelation function.

quant-ph↗

arXiv2022

Negative Compressability of Non-Equilibrium Non-Ideal Bose--Einstein Condensate

An ideal equilibrium Bose--Einstein condensate (BEC) is usually considered in the grand canonical ($μV T$) ensemble, which implies the presence of the chemical equilibrium with the environment. However, in most experimental scenarios, the total amount of particles in BEC is determined either by the initial conditions or by the balance between dissipation and pumping. As a result, BEC may possess the thermal equilibrium but almost never the chemical equilibrium. In addition, many experimentally achievable BECs are non-ideal due to interaction between particles. In the recent work [10.1103/PhysRevLett.128.065301], it has been shown that invariant subspaces in the system Hilbert space appear in non-equilibrium BEC in the fast thermalization limit. In each of these subspaces, Gibbs distribution is established with a certain number of particles that makes it possible to investigate properties of non-ideal non-equilibrium BEC independently in each invariant subspace. In this work, we analyze the BEC stability due to change in dispersion curve caused by non-ideal interactions in BEC. Generally, non-ideal interactions lead to the redshift or blueshift of the dispertion curve and to the change in the effective mass of the particles. We show that the redshift of the dispersion curve can lead to the negative compressibility of BEC, whereas the change in the effective mass always makes BEC more stable. We find the explicit condition for the particle density in BEC, at which the negative compressibility appears.

cond-mat.quant-gas↗

arXiv2022

Overcoming the diffraction limit on the size of dielectric resonators using an amplifying medium

Existing methods for the localization of light at the nanoscale use either a structure with negative permittivity, by exploiting subwavelength plasmonic resonances, or a dielectric structure with a high refractive index, which reduces the wavelength. In this paper, we provide an alternative to these two methods based on a modification of the modes of dielectric resonators by means of an active medium. We show that an active medium can promote subwavelength light localization in the dielectric structure. We consider a dielectric layer of size substantially smaller than a half-wavelength of light in the dielectric medium, and demonstrate that at a certain value of gain in the active medium, the phase change on reflection at the layer boundaries compensates for the change in phase due to propagation over the layer. At this value of the gain, the gain-assisted mode forms, in which the phase shift during a round trip of the electromagnetic wave is zero. This gain-assisted mode exists only at a positive gain in the dielectric medium, and can be used to create dielectric lasers and sensors of subwavelength size.

physics.optics↗

arXiv2021

Organic single-photon switch

The recent progress in nanotechnology [1,2] and single-molecule spectroscopy [3-5] paves the way for cost-effective organic quantum optical technologies emergent with a promise to real-life devices operating at ambient conditions. In this letter, we harness $π$-conjugated segments of an organic ladder-type polymer strongly coupled to a microcavity forming correlated collective dressed states of light, so-called of exciton-polariton condensates. We explore an efficient way for all-optical ultra-fast control over the macroscopic condensate wavefunction via a single photon. Obeying Bose statistics, exciton-polaritons exhibit an extreme nonlinearity undergoing bosonic stimulation [6] which we have managed to trigger at the single-photon level. Relying on the nature of organic matter to sustain stable excitons dressed with high energy molecular vibrations we have developed a principle that allows for single-photon nonlinearity operation at ambient conditions opening the door for practical implementations like sub-picosecond switching, amplification and all-optical logic at the fundamental limit of single light quanta.

cond-mat.mes-hall↗

arXiv2021

Exact analytical solution for density matrix of a non-equilibrium polariton Bose-Einstein condensate

In this letter, we give an analytical quantum description of a non-equilibrium polariton Bose-Einstein condensate (BEC) based on the solution of the master equation for the full polariton density matrix in the limit of fast thermalization. We find the density matrix of a non-equilibrium BEC, that takes into account quantum correlations between all polariton states. We show that the formation of BEC is accompanied by the build-up of cross-correlations between the ground state and the excited states reaching their highest values at the condensation threshold. Despite the non-equilibrium nature of polariton systems, we show the average population of polariton states exhibits the Bose-Einstein distribution with an almost zero effective chemical potential above the condensation threshold similar to an equilibrium BEC. We demonstrate that above threshold the effective temperature of polariton condensate drops below the reservoir temperature.

cond-mat.quant-gas↗