arXiv subjects

A. V. Yulin

Publications and source records attributed to A. V. Yulin.

At least 19 recordsLinked to original sources

arXiv2026

Josephson and Spin Currents in Coupled Polariton Condensates

We analyze particle and spin currents in networks of coupled spinor exciton-polariton condensates arranged as plaquettes and regular polygonal rings. In closed geometries, spin-conserving and TE-TM-induced spin-flip tunnelling combine to generate circulating particle currents, hidden spin counterflows, and bond-dependent spin-current patterns. For the minimal geometries - an equilateral triangle, and a square plaquette - we derive analytical expressions for edge-resolved currents from stationary configurations obtained by energy minimization. We then show how particle, in-plane spin, and out-of-plane spin currents partition the parameter plane and provide direct signatures of the equilibrium phases. Finally, we apply the same current-resolved diagnostics to larger rings, where winding numbers and a branch-invariant common-phase coherence metric organize the resulting phase structure.

cond-mat.mes-hall↗

arXiv2026

Hidden chirality and half-vortex formation in exciton-polariton condensates

We show that a radially symmetric, nonresonantly pumped spinor exciton-polariton condensate can acquire chirality without a rotating drive, chiral geometry, or pump orbital angular momentum. Spin relaxation in a two-reservoir system shifts the reservoir-induced blueshift relative to the gain profile, creating an effective non-Hermitian chiral potential. A reduced angular-mode theory reveals tunable exceptional points and non-reciprocal coupling between counter-rotating modes. Full driven-dissipative Gross-Pitaevskii simulations show that this hidden chirality enables all-optical formation of spin-selective half-vortices.

cond-mat.mes-hall↗

arXiv2026

Polalrized reservoirs in dynamics of polariton condensation

We review the problem of description of the dynamics of driven-disspipative spinor polariton condensates, focusing on the terms corresponding to the coupling between a macroscopic wavefunction of the condensdate and incoherent excitonic reservoir created by a non-resonant pump. We demonstrate that the existing version of the theory breaks down in case, when reservoir has non-zero components of the Stokes vector corresponding to in-plane linear polarization. The polarization invariant theory of reservoir to condensate coupling is formulated with use of the spin density matrix formalism.

physics.optics↗

arXiv2026

Acoustic spin resonance in polariton condensates

We theoretically investigate acoustic spin resonance in a spatially homogeneous spinor polariton condensate. A longitudinal acoustic wave generates a time-periodic strain-induced effective magnetic field acting on the condensate pseudospin. When this field is transverse to the static in-plane linear-polarization splitting, it resonantly drives polarization oscillations. We show that spin-dependent interactions shift the resonance and produce nonlinear line shapes, while gain, reservoir dynamics, and spin relaxation make the response dissipative and history-dependent, producing amplitude hysteresis. In the presence of lifetime anisotropy, the condensate can develop a bifurcated stationary state with finite circular polarization, and a resonant acoustic drive can switch between the corresponding out-of-plane branches. A Zeeman splitting provides an additional conservative knob for tuning the resonance frequency. Our results identify coherent acoustic driving as a route to resonant, nonlinear, and switchable control of polariton pseudospin dynamics.

cond-mat.mes-hall↗

arXiv2026

Ground-State Selection by Pure Energy Relaxation in Polariton Condensates

We study nonequilibrium mode selection in dissipative exciton-polariton condensates incoherently pumped through an excitonic reservoir in the presence of pure energy relaxation. For a confined system in which a vortex mode is selected at threshold, we show that energy relaxation qualitatively changes the condensation scenario: as the pump increases, the asymptotic state evolves from a vortex condensate to a rotating mixed state and then to a ground-state condensate. Pure energy relaxation thus destabilizes condensation into excited states and promotes ground-state selection.

cond-mat.mes-hall↗

arXiv2026

Synchronization-induced flat bands in driven-dissipative dimer-waveguide chains

Flat bands in driven-dissipative systems offer a route to engineer strongly localized, long-lived excitations, yet their selective population via incoherent pumping remains an open challenge. We study a one-dimensional chain of coupled lasing dimers arranged in a cross-stitch geometry and show that the synchronization regime of the individual dimers, controllable through pump intensity or inter-resonator distance, determines the character of the flat band hosted by the chain. In the in-phase (ferromagnetic) regime, the flat band appears as a subdominant, damped mode in the linear excitation spectrum. In the antiphase (antiferromagnetic) regime, by contrast, the dimers decouple and the flat band becomes the dominant, neutrally stable mode: it corresponds to an infinite family of Goldstone modes arising from the independent phase rotations of non-interacting dimers, and its compact localized states are directly observable in the noise response spectrum. Switching between these two regimes via pump control constitutes a pump-induced phase transition of the lasing lattice. Our results establish synchronization engineering as a practical mechanism for selective flat-band population in driven-dissipative optical systems, and open new avenues for studying flat-band physics, including nonlinear effects, Fano resonances, and excitation coherence in experimentally accessible laser and polariton platforms.

physics.optics↗

arXiv2025

Quantum hydrodynamics of a polariton fluid: pure energy relaxation terms

Cavity polaritons, hybrid half-light half-matter excitations in quantum microcavities in the strong-coupling regime demonstrate clear signatures of quantum collective behavior, such as analogues of Bose-Einstein condensate and superfluidity at remarkably high temperatures. The analysis of the formation of these states demands an account of the relaxation processes in the system. Although there are well-established approaches for the description of some of them, such as finite lifetime polariton, an external optical pump, and coupling with an incoherent excitonic reservoir, the treatment of pure energy relaxation in a polariton fluid still remains a puzzle. Here, based on the quantum hydrodynamics approach, we derive the corresponding equations where the energy relaxation term appears naturally. We analyze in detail how it affects the dynamics of polariton droplets and the dispersion of elementary excitations of a uniform polariton condensate. Although we focus on the case of cavity polaritons, our approach can be applied to other cases of bosonic condensates, where the processes of energy relaxation play an important role.

cond-mat.mes-hall↗

arXiv2025

Spin relaxation in a polariton fluid: quantum hydrodynamic approach

Cavity polaritons, the elementary excitations appearing in quantum microcavities in the strong-coupling regime, reveal clear signatures of quantum collective behavior. The combination of unique spin structure and strong nonlinear response opens the possibility of direct experimental observation of a plethora of nontrivial optical polarization phenomena. Spin relaxation processes are of crucial importance here. However, a mathematical formalism for their coherent description is still absent. In the present paper, based on the quantum hydrodynamics approach for a two-component liquid, we derive the set of the corresponding equations where both energy and spin relaxation terms appear naturally. We analyze in detail how these terms affect the dynamics of spinor polariton droplets in the external magnetic field and the dispersion of elementary excitations of a uniform polariton condensate. Although we focus on the case of cavity polaritons, our approach can be applied to other cases of spinor bosonic condensates, where the processes of spin relaxation play a major role.

cond-mat.mes-hall↗

arXiv2025

Phase locking of ring-shaped exciton-polariton condensates to coherent optical drive

The effect of an additional quasi-resonant drive on the dynamics of the ring-shaped incoherently pumped polariton condensates carrying angular momentum (vorticity) is studied theoretically. Numerical simulations of the 2D and 1D Gross-Pitaevskii equations show that the difference of the topological charges(vorticities) $Δn$ of the condensate and the quasi-resonant coherent drive plays a crucial role in the synchronization dynamics. It is shown that in an axially symmetric system, synchronization can only occur if $|Δn| = 0$, whereas in the other cases the phase of the condensate cannot be locked to the phase of the coherent drive. To explain this effect observed in the numerical simulations a perturbation theory is developed. The theory shows that the phase slip between the condensate and the coherent drive can be understood in terms of the motion of 2$π$ kinks. It is shown that the breaking of the axial symmetry can stop the motion of the kinks, allowing the phase locking of the condensate to the coherent drive.

cond-mat.mes-hall↗

arXiv2023

Transport regimes for exciton-polaritons in disordered microcavities

Light-matter coupling in a planar optical cavity substantially modifies the transport regimes in the system in presence of a short range excitonic disorder. Basing on Master equation for a resonantly coupled exciton-photon system, and treating disorder scattering in the Born-Markov approximation we demonstrate the onset of ballistic and diffusive transport regimes in the limits of weak and strong disorder respectively. We show that transport parameters governing the crossover between these two regimes strongly depend on the parameters characterizing light-matter coupling, in particular Rabi energy and detuning between excitonic and photonic modes. The presented theory agrees with recent experimental data on transport in disordered organic microcavities.

cond-mat.mtrl-sci↗

arXiv2023

Persistent polarization oscillations in ring-shape polariton condensates

We predict the limit cycle solution for a ring-shape bosonic condensate of exciton-polaritons confined in an optically induced rotating trap. The limit cycle manifests itself with polarization oscillations on a characteristic timescale of tens of picoseconds. The effect arises due to the interplay between orbital motion and the polarization degree of freedom. It is specific to spinor bosonic condensates and would be absent in a scalar case, where a bi-stability of stationary solutions would be observed instead. This work offers a tool of initialisation and control of qubits based on superpositions of polariton condensates characterised by different topologic charges.

physics.optics↗

arXiv2023

Vorticity of polariton condensates in rotating traps

This work is inspired by recent experiments on the formation of vortices in exciton-polariton condensates placed in rotating optical traps. We study theoretically the dynamics of formation of such vortices and elucidate the fundamental role of the mode competition effect in determining the properties of stationary polariton states triggered by stimulated scattering of exciton-polaritons. The interplay between linear and non-linear effects is shown to result in a peculiar polariton dynamics. However, near the lasing threshold, the predominant contribution of the nonlinear effects is the saturation of the linear gain.

physics.optics↗

arXiv2022

Spin resonance induced by a mechanical rotation of a polariton condensate

We study theoretically the polarization dynamics in a ring-shape bosonic condensate of exciton-polaritons confined in a rotating trap. The interplay between the rotating potential and TE-TM splitting of polariton modes offers a tool of control over the spin state and the angular momentum of the condensate. Specific selection rules describing the coupling of pseudospin and angular momentum are formulated. The resonant coupling between states having linear and circular polarizations leads to the polarization beats. The effect may be seen as a polariton analogy to the electronic magnetic resonance in the presence of constant and rotating magnetic fields. Remarkably, spin beats are induced by a purely mechanical rotation of the condensate.

physics.optics↗

arXiv2022

Bright and dark solitons in the systems with strong light-matter coupling: exact solutions and numerical simulations

We theoretically study bright and dark solitons in an experimentally relevant hybrid system characterized by strong light-matter coupling. We find that the corresponding two-component model supports a variety of coexisting moving solitons including bright solitons on zero and nonzero background, dark-gray and gray-gray dark solitons. The solutions are found in the analytical form by reducing the two-component problem to a single stationary equation with cubic-quintic nonlinearity. All found solutions coexist under the same set of the model parameters, but, in a properly defined linear limit, approach different branches of the polariton dispersion relation for linear waves. Bright solitons with zero background feature an oscillatory-instability threshold which can be associated with a resonance between the edges of the continuous spectrum branches. `Half-topological' dark-gray and nontopological gray-gray solitons are stable in wide parametric ranges below the modulational instability threshold, while bright solitons on the constant-amplitude pedestal are unstable.

nlin.PS↗

arXiv2020

Optical analogue of Dresselhaus spin-orbit interaction in photonic graphene

The concept of gauge fields plays a significant role in many areas of physics from particle physics and cosmology to condensed matter systems, where gauge potentials are a natural consequence of electromagnetic fields acting on charged particles and are of central importance in topological states of matter. Here, we report on the experimental realization of a synthetic non-Abelian gauge field for photons in a honeycomb microcavity lattice. We show that the effective magnetic field associated with TE-TM splitting has the symmetry of Dresselhaus spin-orbit interaction around Dirac points in the dispersion, and can be regarded as an SU(2) gauge field. The symmetry of the field is revealed in the optical spin Hall effect (OSHE), where under resonant excitation of the Dirac points precession of the photon pseudospin around the field direction leads to the formation of two spin domains. Furthermore, we observe that the Dresselhaus field changes its sign in the same Dirac valley on switching from s to p bands in good agreement with the tight binding modelling. Our work demonstrating a non-Abelian gauge field for light on the microscale paves the way towards manipulation of photons via spin on a chip.

cond-mat.mes-hall↗

arXiv2020

Dynamics of particles trapped by dissipative domain walls

In this Letter we study the interactions of the dissipative domain walls with dielectric particles. It is shown that particles can be steadily trapped by the moving domain walls. The influence of the ratchet effect on particle trapping is considered. It is demonstrated, that the ratchet effect allows to obtain high accuracy in particle manipulation.

physics.optics↗

arXiv2019

Resonant excitation of acoustic waves in one-dimensional exciton-polariton systems

We analyze the interaction of exciton-polariton condensates in a one-dimensional semiconductor microcavity with acoustic phonons. We consider the case of a coherently pumped condensate and demonstrate that upon passing of a certain threshold the parametric instability in the system leads to the generation of a coherent acoustic wave and additional polariton harmonics. The process is strongly affected by exciton-exciton interactions which lead to the appearance of the effects of the bistability and hysteresis in the system.

cond-mat.mes-hall↗

arXiv2019

Complex dynamics of optical solitons interacting with nanoparticles

In this Letter we further develop the proposed approach of optical manipulation based on the interactions of non-linear optical effects with nanoparticles. The interaction of the dissipative optical solitons with nanoparticles is studied numerically. It is shown that the attraction of the nanoparticles to the solitons can result in the formation of a stable bound state of the solitons and the nanoparticles. The collision of the solitons with different numbers of trapped particles is studied, and it is shown that the collision of the solitons can result in releasing or redistributing the nanoparticles between the solitons. It is demonstrated that the particle mediated interaction between the solitons can affect their dynamics significantly. The reported effects can be successfully used for optical manipulation of nanoparticles and pave a way for efficient control over their dynamics on nanoscale.

physics.optics↗