arXiv subjects

Sergey Alyatkin

Publications and source records attributed to Sergey Alyatkin.

16 recordsLinked to original sources

arXiv2026

Observation of an aperiodic polariton monotile

A plethora of unconventional localization phenomena and fractal features of linear spectrum observed in quasiperiodic structures have been accompanied by a long-standing quest for the geometrical elements and structures that permit tilings of the plane, but only in a non-periodic manner. Until 2024, it was believed that such quasiperiodic structures, or quasicrystals, could only be composed of at least two different tiles. Surprisingly, a newly discovered class of quasicrystals requires only one elementary monotile. However, its physical realization and study of propagating coherent excitations in this novel setting remained elusive. Here we optically sculpt aperiodic quasicrystals composed of "einstein" monotiles in an inorganic microcavity and observe nontrivial relative phases of the exciton-polariton condensates nonresonantly excited at the vertices of each monotile. Utilizing energy-resolved tomography in momentum-space, we reveal the formation of distinct Bragg peaks with six-fold symmetry and Dirac-like spectral fingerprints, intrinsic to the underlying graphene-like structure, while interferometric phase reconstruction shows a nontrivial synchronization pattern distinct from both periodic triangular lattices and Penrose quasicrystals. Our work demonstrates that monotiles can be converted into a programmable driven-dissipative artificial material, where long-range coherence coexists with enforced geometric aperiodicity, producing synchronization and spectral responses distinct from both periodic and conventional quasicrystalline tilings.

cond-mat.quant-gas↗

arXiv2026

Single-Shot Flow Spectroscopy of a Polariton Condensate: Kibble-Zurek and Kolmogorov-Like Scaling

Quantized vortices are fundamental topological excitations of quantum fluids. We report single-shot interferometric measurements of spontaneous vortex nucleation in a room-temperature organic exciton-polariton condensate. From hundreds of independent realizations we find random vortex-core positions and unbiased circulation, consistent with intrinsically stochastic, unpinned defect formation. The mean vortex number scales with pump power above threshold with an exponent consistent with Kibble-Zurek freeze-out in a driven-dissipative condensate. Using reconstructed phase maps we obtain single-shot flow fields, compute the incompressible component, and extract kinetic-energy spectra. Vortex-containing realizations develop a robust Kolmogorov-like segment with Einc(k) proportional to k^(-5/3) over a finite k range, indicating the onset of turbulent spectral scaling in a quantum fluid of light. These results establish single-shot access to phase and flow as a direct route to quantifying stochastic defect formation and emerging turbulence in polariton condensates.

cond-mat.mes-hall↗

arXiv2025

Tailoring the resonant spin response of a stirred polariton condensate

We report on the enhancement of the spin coherence time (T2) by almost an order-of-magnitude in exciton-polariton condensates through driven spin precession resonance. Using a rotating optical trap formed by a bichromatic laser excitation, we synchronize the trap stirring frequency with the condensate intrinsic Larmor precession, achieving an order of magnitude increase in spin coherence. By tuning the optical trap profile via excitation lasers intensity, we precisely control the resonance width. Here we present a theoretical model that explains our experimental findings in terms of the mutual synchronization of the condensate circular polarization components. Our findings underpin the potential of polariton condensates for spinoptronic devices and quantum technologies.

cond-mat.quant-gas↗

arXiv2024

Quantum Fluids of Light in 2D Artificial Reconfigurable Aperiodic Crystals with Tailored Coupling

Aperiodic crystals are the intermediates between strictly periodic crystalline matter and amorphous solids. The lack of translational symmetry combined with intrinsic long-range order endows aperiodic crystals with unique physical characteristics, while at the same time dramatically enriching the spectrum and localization properties. Here, we demonstrate exciton-polariton condensation in a two-dimensional Penrose tiling with $C_{10}$ rotational symmetry - the first signature of quasicrystalline order in a quantum fluid of light. We identify a regime, wherein near-perfect delocalization and synchronization of a quantum fluid of light occurs at mesoscopic length-scales extending beyond 100x the healing length and the size of each individual condensate. Realizing long-range order in fully reconfigurable aperiodic crystals of nonlinear, and open-dissipative quantum fluids, lays the foundations for testing a broad range of universality classes of continuous phase transitions beyond the limits of mathematically verifiable models in regular lattices.

cond-mat.quant-gas↗

arXiv2024

Antiferromagnetic Ising model in a triangular vortex lattice of quantum fluids of light

Vortices are topologically distinctive objects appearing as phase twists in coherent fields of optical beams and Bose-Einstein condensates. Structured networks and artificial lattices of coupled vortices could offer a powerful platform to study and simulate interaction mechanisms between constituents of condensed matter systems, such as antiferromagnetic interactions, by replacement of spin angular momentum with orbital angular momentum. Here, we realize such a platform using a macroscopic quantum fluid of light based on exciton-polariton condensates. We imprint all-optical hexagonal lattice that results into a triangular vortex lattice, with each cell having a vortex of charge l = +-1. We reveal that pairs of coupled condensates spontaneously arrange their orbital angular momentum antiparallel, implying a form of artificial orbital "antiferromagnetism". We discover that correlation exists between the emergent vortex patterns in triangular condensate lattices and the low-energy solutions of the corresponding antiferromagnetic Ising system. Our study offers a path toward spontaneously ordered vortex arrays with nearly arbitrary configurations and controlled couplings.

cond-mat.mes-hall↗

arXiv2023

Vortex clusters in a stirred polariton condensate

The response of superfluids to the external rotation, evidenced by emergence of quantised vortices, distinguishes them from conventional fluids. In this work, we demonstrate that the number of vortices in a stirred polariton condensate depends on the characteristic size of the employed rotating potential induced by the nonresonant laser excitation. For smaller sizes, a single vortex with a topological charge of +-1 corresponding to the stirring direction is formed. However, for larger optical traps, clusters of two or three co-rotating vortices appear in the narrow range of GHz stirring speed.

cond-mat.mes-hall↗

arXiv2023

Optically driven spin precession in polariton condensates

External driving of spinor degrees of freedom by magnetic or optical fields in quantum systems underpin many applications ranging from nuclear magnetic resonance to coherent state control in quantum computing. Although spinor polariton condensates are offering a flexible platform for spinoptronic applications, strong inter-particle interactions limit their spin coherence. Here, we introduce an all-optically driven spin precession in microcavity polariton condensates that eliminates depolarisation, through a radio frequency modulation of a spatially rotating, asymmetric exciton reservoir that both confines, and actively replenishes the polariton condensate. We realise several GHz driven spin precession with a macroscopic spin coherence time that is limited only by the extraneous to the condensate, frequency drift of the composite pumping sources. Our observations are supported by mean field modelling and evidence a driven-dissipative quantum fluidic analogue of the nuclear magnetic resonance effect.

physics.optics↗

arXiv2023

Quantum Vortex Formation in the "Rotating Bucket'' Experiment with Polariton Condensates

The appearance of quantised vortices in the classical ``rotating bucket'' experiments of liquid helium and ultracold dilute gases provides the means for fundamental and comparative studies of different superfluids. Here, we realize the ``rotating bucket'' experiment for optically trapped quantum fluid of light based on exciton-polariton Bose-Einstein condensate in semiconductor microcavity. We utilise the beating note of two frequency-stabilized single-mode lasers to generate an asymmetric time-periodic rotating, non-resonant excitation profile that both injects and stirs the condensate through its interaction with a background exciton reservoir. The pump-induced external rotation of the condensate results in the appearance of a co-rotating quantised vortex. We investigate the rotation-frequency dependence and reveal the range of stirring frequencies (from 1 to 4 GHz) which favors quantised vortex formation. We describe the phenomenology using the generalised Gross-Pitaevskii equation. Our results enable the study of polariton superfluidity on a par with other superfluids, as well as deterministic, all-optical control over structured nonlinear light.

cond-mat.quant-gas↗

arXiv2022

Spontaneous formation of time-periodic vortex cluster in nonlinear fluids of light

We demonstrate spontaneous formation of a nonlinear vortex cluster state in a microcavity exciton-polariton condensate with time-periodic sign flipping of its topological charges at the GHz scale. When optically pumped with a ring-shaped nonresonant laser, the trapped condensate experiences intricate high-order mode competition and fractures into two distinct trap levels. The resulting mode interference leads to robust condensate density beatings with periodic appearance of orderly arranged phase singularities. Our work opens new perspectives on creating structured free-evolving light, and singular optics in the strong light-matter coupling regime.

cond-mat.mes-hall↗

arXiv2022

Solving the max-3-cut problem using synchronized dissipative networks

Many computational problems are intractable through classical computing and, as Moore's law is drawing to a halt, demand for finding alternative methods in tackling these problems is growing. Here, we realize a liquid light machine for the NP-hard max-3-cut problem based on a network of synchronized exciton-polariton condensates. We overcome the binary limitation of the decision variables in Ising machines using the continuous-phase degrees of freedom of a coherent network of polariton condensates. The condensate network dynamical transients provide optically-fast annealing of the XY Hamiltonian. We apply the Goemans and Williamson random hyperplane technique, discretizing the XY ground state spin configuration to serve as ternary decision variables for an approximate optimal solution to the max-3-cut problem. Applications of the presented coherent network are investigated in image-segmentation tasks and in circuit design.

quant-ph↗

arXiv2021

Quantum fluids of light in all-optical scatterer lattices

One of the recently established paradigms in condensed matter physics is examining a system's behaviour in artificially constructed potentials, giving insight into physical phenomena of quantum fluids in hard-to-reach settings. A prominent example is the matter-wave scatterer lattice, also known as the barrier lattice or repulsive Dirac comb. There, high energy matter waves undergo transmission and reflection through narrow width barriers leading to stringent phase matching conditions with subsequent lattice band formation. It is one of the most well taught system in quantum mechanics but its realisation for macroscopic matter-wave fluids has remained elusive, in contrast to evanescently coupled lattice sites or waveguides. Here, we implement and study a system of exciton-polariton condensates in a non-Hermitian Lieb lattice of scatterer potentials by optically injecting incoherent exciton clouds which both emit, and interact with traveling polariton waves. By fine tuning the lattice parameters, we reveal a nonequilibrium phase transition between two distinct regimes of polariton condensation: a scatterer lattice of gain guided polaritons condensing on the lattice potential maxima, and trapped polaritons condensing in the lattice potential minima. The transition is characterised by multimodal condensation due to gain competition between the two regimes. Energy tomography on the polariton emission enables us to measure the intricate band structure of the optically induced lattices. Our results pave the way towards unexplored physics of non-Hermitian fluids in non-stationary mixtures of confined and freely expanding waves.

cond-mat.mes-hall↗

arXiv2021

Geometric frustration in polygons of polariton condensates creating vortices of varying topological charge

Vorticity is a key ingredient to a broad variety of fluid phenomena, and its quantised version is considered to be the hallmark of superfluidity. Circulating flows that correspond to vortices of a large topological charge, termed giant vortices, are notoriously difficult to realise and even when externally imprinted, they are unstable, breaking into many vortices of a single charge. In spite of many theoretical proposals on the formation and stabilisation of giant vortices in ultra-cold atomic Bose-Einstein condensates and other superfluid systems, their experimental realisation remains elusive. Polariton condensates stand out from other superfluid systems due to their particularly strong interparticle interactions combined with their non-equilibrium nature, and as such provide an alternative testbed for the study of vortices. Here, we non-resonantly excite an odd number of polariton condensates at the vertices of a regular polygon and we observe the formation of a stable discrete vortex state with a large topological charge as a consequence of antibonding frustration between nearest neighbouring condensates.

cond-mat.mes-hall↗

arXiv2020

Lotka-Volterra population dynamics in coherent and tunable oscillators of trapped polariton condensates

We demonstrate a regime in which matter-wave condensates of exciton-polaritons trapped in an elliptically shaped two-dimensional potential appear as a coherent mixture of ground and first-excited state of the quantum harmonic oscillator. This system resembles an optically controllable two-level system and produces near terahertz harmonic oscillations of the condensate's center of mass along the major axis of the elliptical trapping potential. The population ratio between the two trap levels is tunable through the excitation laser power and is shown to follow Lotka-Volterra dynamics. We demonstrate coherence formation between two spatially displaced trapped condensate oscillators - the polaritonic analogue of Huygen's clock synchronization for coupled condensate oscillators.

cond-mat.mes-hall↗

arXiv2020

Coherence Revivals of a Spinor Polariton Condensate from Self-induced Larmor Precession

First order coherence measurements of a polariton condensate, reveal a regime where the condensate pseudo-spin precesses persistently within the driving optical pulse. Within a single 20 $μ$s optical pulse the condensate pseudo-spin performs over $10^5$ precessions with striking frequency stability. The condensate maintains its phase coherence even after a complete precession of the spin vector, making the observed state by a definition a spin coherent state. The emergence of the precession is traced to the polariton interactions that give rise to a self-induced out-of-plane magnetic field that in turn drives the spin dynamics. We find that the Larmor oscillation frequency scales with the condensate density, enabling external tuning of this effect by optical means. The stability of the system allows for the realization of integrated optical magnetometry devices with the use of materials with enhanced exciton $g$-factor and can facilitate spin squeezing effects and active coherent control on the Bloch sphere in polariton condensates.

cond-mat.mes-hall↗

arXiv2019

Giant increase of temporal coherence in optically trapped polariton condensate

Coherent bosonic ensembles offer the promise of harnessing quantum effects in photonic and quantum circuits. In the dynamic equilibrium regime, the application of polariton condensates is hindered by exciton-polariton scattering induced de-coherence in the presence of a dark exciton reservoir. By spatially separating the condensate from the reservoir, we drive the system into the weak interaction regime, where the ensemble coherence time exceeds the individual particle lifetime by nearly three orders of magnitude. The observed nanosecond coherence provides an upper limit for polariton self-interactions. In contrast to conventional photon lasers, we observe an increased contribution from the super-Poissonian component of the condensate to the overall particle number fluctuations. Coupled with the recent emergence of a quantum regime in polaritonics, coherence times extended to several nanoseconds favour the realization of quantum information protocols.

cond-mat.quant-gas↗

arXiv2019

Optical control of synchronous phases in a programmable polariton cell

We demonstrate deterministic control of the nearest and next-nearest neighbor coupling in the unit cell of a square lattice of microcavity exciton-polariton condensates. We tune the coupling in a continuous and reversible manner by optically imprinting potential barriers of variable height, in the form of spatially localized incoherent exciton reservoirs that modify the particle flow between condensates. By controlling the couplings in a $2\times2$ polariton cluster, we realize ferromagnetic, anti-ferromagnetic and paired ferromagnetic phases. Our approach paves the way towards simulating complex condensed matter phases through precise control of the individual couplings in networks of optical nonlinear oscillators.

cond-mat.mes-hall↗