arXiv subjects

Vladislav V. Yakovlev

Publications and source records attributed to Vladislav V. Yakovlev.

At least 19 recordsLinked to original sources

arXiv2026

Quantum Ghost Spectroscopy Reveals Hidden Electronic Coherence in Molecular Aggregates

Ultrafast spectroscopy of molecular systems is fundamentally constrained by the Fourier uncertainty principle: high temporal resolution smears out electronic state signatures, while high spectral resolution obscures dynamic information. Here we overcome this limitation using time-resolved quantum ghost spectroscopy (tr-QGS) with entangled photon pairs, which enables independent control of temporal and spectral scales. We apply this approach to perylene bismide (PBI-1) trimers for energy transfer,by combining a quantum description of light-molecule interaction with time-dependent density matrix renormalization group (TD-DMRG) simulations. This explicitly includes five vibrational modes and nonadiabatic coupling between electronic states. Our simulations reveal that tr-QGS uniquely captures electronic coherence oscillating at 0.7 eV for >50 fs, a signature of nonadiabatic coupling that was obscured in conventional time-resolved fluorescence due to Fourier-limited broadening. Moreover, we observe a direct transfer from electronic to vibrational coherence at 200 fs, providing real-time visualization of vibronic relaxation pathways. The entangled photon correlation enables a sensitivity below the shot-noise limit and suppresses photobleaching artifacts that plague classical measurements. These results establish tr-QGS as a transformative tool for interrogating nonadiabatic dynamics in molecular aggregates, light-harvesting complexes, and photocatalysts, offering a route to reveal quantum coherence in chemistry with unprecedented time-energy precision.

quant-ph↗

arXiv2026

Quantum Squeezing Enhanced Photothermal Microscopy

Label-free optical microscopy through absorption or scattering spectroscopy provides fundamental insights across biology and materials science, yet its sensitivity remains fundamentally limited by photon shot noise. While recent demonstrations of quantum nonlinear microscopy show sub-shot-limited sensitivity, they are intrinsically limited by availability of high peak-power squeezed light sources. Here, we introduce squeezing-enhanced photothermal (SEPT) microscopy, a quantum imaging technique that leverages twin-beam quantum correlations to detect absorption induced signals with unprecedented sensitivity. SEPT achieves 3.5 dB noise suppression beyond the standard quantum limit, enabling a 2.5-fold increase in imaging throughput or 31% reduction in pump power, while providing an unmatched versatility through the intrinsic compatibility between continuous-wave squeezing and photothermal modulation. We showcase SEPT applications by providing high-precision characterization of nanoparticles and revealing subcellular structures, such as cytochrome c, that remain undetectable under shot-noise-limited imaging. By combining label-free contrast, quantum-enhanced sensitivity, and compatibility with existing microscopy platforms, SEPT establishes a new paradigm for molecular absorption imaging with far-reaching implications in cellular biology, nanoscience, and materials characterization.

physics.optics↗

arXiv2025

High-fidelity microsecond-scale cellular imaging using two-axis compressed streak imaging fluorescence microscopy

Compressed streak imaging (CSI) is a computational imaging strategy that can acquire video at over 150 trillion frames per second. Despite this achievement, CSI faces challenges in detecting subtle intensity fluctuations in slow-moving, continuously illuminated objects. This limitation, largely attributable to high streak compression and motion blur, has curtailed the broader adoption of CSI in cellular fluorescence microscopy. To address these issues and expand the utility of CSI, we developed a two-axis compressed streak imaging (TACSI) method that results in significant improvements to the reconstructed video fidelity. TACSI introduces a second scanning axis which shuttles a conjugate image of the object with respect to the coded aperture. The moving image decreases the streak compression ratio and produces a "flash and shutter" phenomenon that reduces coded aperture motion blur, overcoming the limitations of current CSI technologies. This approach is supported with an analytical model describing the TACSI compression ratio, along with simulated and empirical measurements. We demonstrate TACSI's ability to measure rapid variations in cell membrane potentials, previously unattainable with conventional CSI. This method has broad implications for high-speed photography, including visualization of action potentials, muscle contractions, and enzymatic reactions that occur on microsecond and faster timescales using fluorescence microscopy.

physics.optics↗

arXiv2025

Modular and Automated Workflow for Streamlined Raman Signal Analysis

Raman spectroscopy is a powerful tool for material characterization. However, careful preprocessing is required for the identification and handling of noise, baseline drift, and random spikes. This paper presents a comprehensive approach to generating and preprocessing Raman spectra. Additionally, we describe methods for fitting Voigt peaks to the spectrum to determine peak parameters. The effectiveness of these methods is demonstrated using both synthetic and real Raman spectra, with code provided in an open-source GitHub repository.

physics.optics↗

arXiv2025

Fluorescence Lifetime Imaging Microscopy Analysis of Isolated Melanosomes

Melanosomes are organelles found in a wide variety of tissues throughout the animal kingdom. They contain a variety of biological molecules, but the dominant constituent is the pigment melanin, and many functions ascribed to melanosomes, such as photoprotection, are uniquely enabled by the chemical properties and structures of the melanins they contain. In this report, we used, for the first time, Fluorescence Lifetime Imaging Microscopy (FLIM) to examine fluorescent properties of pigments in melanosomes and evaluate their time evolution upon extended laser irradiation. We discovered a relatively short-lived component in fluorescence emission and revealed significant changes in lifetimes upon irradiation indicating structural photoinduced changes to melanin occurring on a time scale of minutes, with observations extending up to one hour.

physics.bio-ph↗

arXiv2025

Viscoelastic Characterization of Melanoma Cells Using Brillouin Spectroscopy

In this study, Brillouin spectroscopy was employed to investigate the viscoelastic properties of melanoma cells in vitro. Using a custom-built confocal Brillouin microspectrometer, we obtained Brillouin shifts and full width at half maximum (FWHM) values, enabling the non-invasive assessment of cellular stiffness and viscosity. The Brillouin spectra revealed the biomechanical characteristics of melanoma cells, with measured shifts and FWHM values providing a detailed viscoelastic profile. These findings demonstrate the capability of Brillouin microscopy to probe the mechanical properties of cancer cells at the subcellular level. This technique holds significant potential for advancing cancer research by providing insights into the mechanical behavior of melanoma cells, which could inform the development of diagnostic tools and therapeutic strategies based on cellular biomechanics.

physics.optics↗

arXiv2025

Differentiation of Wild-Type and CRISPR-Modified Colon Cancer Cells Using Brillouin Microscopy

This study investigates the mechanical properties of colon cancer cells through Brillouin microscopy, focusing on the differentiation between wild-type (WT) and CRISPR-modified cells. Brillouin microspectroscopy, a non-invasive technique, was employed to measure Brillouin shifts and full width at half maximum (FWHM) values of the cells in vitro. Using a custom-built confocal Brillouin microspectrometer, both WT and CRISPR-modified cells exhibited distinct mechanical responses. Statistical analysis revealed that WT cells had different stiffness and viscosity compared to CRISPR-modified cells, as indicated by their Brillouin shift and FWHM values. The data suggest that Brillouin spectroscopy offers a viable method to differentiate between normal and mutated cells at the subcellular level, providing new insights into cellular mechanical properties relevant to cancer research. These findings hold potential for advancing non-invasive diagnostic techniques and understanding cellular mechanics in oncology.

physics.bio-ph↗

arXiv2025

Deep ultraviolet resonant Raman (DUVRR) spectroscopy for spectroscopic evaluation and disinfection of food and agricultural samples

The increasing demands on modern plant and food production due to climate change, regulatory pressures, and the Sustainable Development Goals necessitate advanced photonic technologies for improved sustainability. Deep ultraviolet resonant Raman (DUVRR) spectroscopy offers precise spectral fingerprinting and potential disinfection capabilities, making it a promising tool for agricultural and food sciences. We developed a cost-effective, portable DUVRR spectroscopy system using a mercury (Hg) lamp as the excitation source at 253.65 \unit{\nano\meter}. The system was tested on diverse samples, including alcohol solvents, organic extracts, and industrial chemicals. The DUVRR system successfully resolved sub-1000 \unit{\per\centi\meter} Raman peaks, enabling detailed spectral fingerprints of various constituents and biomarkers. The system's high sensitivity and specificity ensure precise identification of nutritional values and food quality. The DUV light used in the system, defined here as less than 260 \unit{\nano\meter}, demonstrated potential disinfection properties, adding significant value for food safety applications. The highly sensitive detection capability of our DUVRR system at low powers has significant implications for plant and agricultural sciences. The detailed spectral information enhances the evaluation of nutritional values, food quality, and ripening processes. This dually-functional system is highly valuable for precision farming, food production, and quality control. Our DUVRR spectroscopy system provides a highly sensitive, affordable, and portable method for the spectroscopic evaluation and disinfection of food and agricultural samples. Its ability to resolve detailed Raman peaks below 1000 \unit{\per\centi\meter}, combined with DUV light's disinfection capabilities, makes it a promising tool for advancing sustainability and safety in agriculture and food production.

physics.optics↗

arXiv2024

Seeing the Invisible through Speckle Images

Scattering obscures information carried by wave by producing a speckle pattern, posing a common challenge across various fields, including microscopy and astronomy. Traditional methods for extracting information from speckles often rely on significant physical assumptions, complex devices, or intricate algorithms. Recently, machine learning has emerged as a scalable and widely adopted tool for interpreting speckle patterns. However, most current machine learning techniques depend heavily on supervised training with extensive labeled datasets, which is problematic when labels are unavailable. To address this, we propose a strategy based on unsupervised learning for speckle recognition and evaluation, enabling to capture high-level information, such as object classes, directly from speckles without labeled data. By deriving invariant features from speckles, this method allows for the classification of speckles and facilitates diverse applications in image sensing. We experimentally validated our strategy through two significant applications: a noninvasive glucose monitoring system capable of differentiating time-lapse glucose concentrations, and a high-throughput communication system utilizing multimode fibers in dynamic environments. The versatility of this method holds promise for a broad range of far-reaching applications, including biomedical diagnostics, quantum network decoupling, and remote sensing.

physics.optics↗

arXiv2024

Deep Learning Enhanced Quantum Holography with Undetected Photons

Holography is an essential technique of generating three-dimensional images. Recently, quantum holography with undetected photons (QHUP) has emerged as a groundbreaking method capable of capturing complex amplitude images. Despite its potential, the practical application of QHUP has been limited by susceptibility to phase disturbances, low interference visibility, and limited spatial resolution. Deep learning, recognized for its ability in processing complex data, holds significant promise in addressing these challenges. In this report, we present an ample advancement in QHUP achieved by harnessing the power of deep learning to extract images from single-shot holograms, resulting in vastly reduced noise and distortion, alongside a notable enhancement in spatial resolution. The proposed and demonstrated deep learning QHUP (DL-QHUP) methodology offers a transformative solution by delivering high-speed imaging, improved spatial resolution, and superior noise resilience, making it suitable for diverse applications across an array of research fields stretching from biomedical imaging to remote sensing. DL-QHUP signifies a crucial leap forward in the realm of holography, demonstrating its immense potential to revolutionize imaging capabilities and pave the way for advancements in various scientific disciplines. The integration of DL-QHUP promises to unlock new possibilities in imaging applications, transcending existing limitations and offering unparalleled performance in challenging environments.

physics.optics↗

arXiv2024

Harnessing quantum light for microscopic biomechanical imaging of cells and tissues

The biomechanical properties of cells and tissues play an important role in our fundamental understanding of the structures and functions of biological systems at both the cellular and subcellular levels. Recently, Brillouin microscopy, which offers a label-free spectroscopic means of assessing viscoelastic properties in vivo, has emerged as a powerful way to interrogate those properties on a microscopic level in living tissues. However, susceptibility to photo-damage and photo-bleaching, particularly when high-intensity laser beams are used to induce Brillouin scattering, poses a significant challenge. This article introduces a transformative approach designed to mitigate photo-damage in biological and biomedical studies, enabling non-destructive, label-free assessments of mechanical properties in live biological samples. By leveraging quantum-light-enhanced stimulated Brillouin scattering (SBS) imaging contrast, the signal-to-noise ratio is significantly elevated, thereby increasing sample viability and extending interrogation times without compromising the integrity of living samples. The tangible impact of this novel methodology is evidenced by a notable three-fold increase in sample viability observed after subjecting the samples to three hours of continuous squeezed-light illumination, surpassing the traditional coherent light-based approaches. The quantum-enhanced SBS imaging holds promise across diverse fields, such as cancer biology and neuroscience where preserving sample vitality is of paramount significance. By mitigating concerns regarding photo-damage and photo-bleaching associated with high-intensity lasers, this technological breakthrough expands our horizons for exploring the mechanical properties of live biological systems, paving the way for a new era of research and clinical applications.

quant-ph↗

arXiv2024

Controlling quasi-parametric amplifications: From multiple PT-symmetry phase transitions to non-Hermitian sensing

Quasi-parametric amplification (QPA) is a nonlinear interaction in which the idler wave is depleted through some loss mechanism. QPA plays an important role in signal amplification in ultrafast photonics and quantum light generation. The QPA process has a number of features characterized by the non-Hermitian parity-time ($\mathcal{PT}$) symmetry. In this report, we explore new interaction regimes and uncover multiple $\mathcal{PT}$-symmetry phase transitions in such QPA process where transitions are particularly sensitive to external parameters. In particular, we demonstrate the feasibility of detection of $10^{-11}$ inhomogeneities of the doped absorber, which is order of magnitude more sensitive than similar measurements performed in a linear absorption regime. In doing so, we reveal a family of $\mathcal{PT}$-symmetry phase transitions appearing in the QPA process and provide a novel nonlinear optical sensing mechanism for precise optical measurements.

physics.optics↗

arXiv2024

Estimation of the number of single-photon emitters for multiple fluorophores with the same spectral signature

Fluorescence microscopy is of vital importance for understanding biological function. However most fluorescence experiments are only qualitative inasmuch as the absolute number of fluorescent particles can often not be determined. Additionally, conventional approaches to measuring fluorescence intensity cannot distinguish between two or more fluorophores that are excited and emit in the same spectral window, as only the total intensity in a spectral window can be obtained. Here we show that, by using photon number resolving experiments, we are able to determine the number of emitters and their probability of emission for a number of different species, all with the same measured spectral signature. We illustrate our ideas by showing the determination of the number of emitters per species and the probability of photon collection from that species, for one, two, and three otherwise unresolvable fluorophores. The convolution Binomial model is presented to model the counted photons emitted by multiple species. And then the Expectation-Maximization (EM) algorithm is used to match the measured photon counts to the expected convolution Binomial distribution function. In applying the EM algorithm, to leverage the problem of being trapped in a sub-optimal solution, the moment method is introduced in finding the initial guess of the EM algorithm. Additionally, the associated Cramér-Rao lower bound is derived and compared with the simulation results.

quant-ph↗

arXiv2023

Optical neural network architecture for deep learning with the temporal synthetic dimension

The physical concept of synthetic dimensions has recently been introduced into optics. The fundamental physics and applications are not yet fully understood, and this report explores an approach to optical neural networks using synthetic dimension in time domain, by theoretically proposing to utilize a single resonator network, where the arrival times of optical pulses are interconnected to construct a temporal synthetic dimension. The set of pulses in each roundtrip therefore provides the sites in each layer in the optical neural network, and can be linearly transformed with splitters and delay lines, including the phase modulators, when pulses circulate inside the network. Such linear transformation can be arbitrarily controlled by applied modulation phases, which serve as the building block of the neural network together with a nonlinear component for pulses. We validate the functionality of the proposed optical neural network for the deep learning purpose with examples handwritten digit recognition and optical pulse train distribution classification problems. This proof of principle computational work explores the new concept of developing a photonics-based machine learning in a single ring network using synthetic dimensions, which allows flexibility and easiness of reconfiguration with complex functionality in achieving desired optical tasks.

physics.optics↗

arXiv2022

Quantum-Enhanced Stimulated Brillouin Scattering Spectroscopy and Imaging

Brillouin microscopy is an emerging label-free imaging technique to assess local viscoelastic properties. Quantum-enhanced stimulated Brillouin scattering is demonstrated for the first time using low power continuous-wave lasers at 795~nm. A signal to noise ratio enhancement of 3.4~dB is reported by using two-mode intensity-difference squeezed light generated with the four-wave mixing process in atomic rubidium vapor. The low optical power and the excitation wavelengths in the water transparency window has the potential to provide a powerful bio-imaging technique for probing mechanical properties of biological samples prone to phototoxicity and thermal effects. The performance enhancement affordable through the use of quantum light may pave the way for significantly improved sensitivity that cannot be achieved classically. The proposed new way of utilizing squeezed light for enhanced stimulated Brillouin scattering can be easily adapted for both spectroscopic and imaging applications in materials science and biology.

physics.optics↗

arXiv2021

En route to nanoscopic quantum optical imaging: counting emitters with photon-number-resolving detectors

Fundamental understanding of biological pathways requires minimally invasive nanoscopic optical resolution imaging. Many approaches to high-resolution imaging rely on localization of single emitters, such as fluorescent molecule or quantum dot. Exact determination of the number of such emitters in an imaging volume is essential for a number of applications; however, in a commonly employed intensity-based microscopy it is not possible to distinguish individual emitters without initial knowledge of system parameters. Here we explore how quantum measurements of the emitted photons using photon number resolving detectors can be used to address this challenging task. In the proposed new approach, the problem of counting emitters reduces to the task of determining differences between the emitted photons and the Poisson limit. We show that quantum measurements of the number of photons emitted from an ensemble of emitters enable the determination of both the number of emitters and the probability of emission. This method can be applied for any type of emitters, including Raman and infrared emitters, which makes it a truly universal way to achieve super-resolution optical imaging. The scaling laws of this new approach are presented by the Cramer-Rao Lower Bounds and define the extent this technique can be used for quantum optical imaging with nanoscopic resolution.

quant-ph↗

arXiv2021

Quasi-edge states and topological Bloch oscillation in the synthetic space

In physics, synthetic dimensions trigger great interest to manipulate light in different ways, while in technology, lithium niobate shows important capability towards on-chip applications. Here, based on the state-of-art technology, we propose and study a theoretical model of dynamically-modulated waveguide arrays with the Su-Schrieffer-Heeger configuration in the spatial dimension. The propagation of light through the one-dimensional waveguide arrays mimics time evolution of field in a synthetic two-dimensional lattice including the frequency dimension. By adding the effective gauge potential, we find quasi-edge state that the intensity distribution manifests not at the boundary as the traditional edge state, which leads to an exotic topologically protected one-way transmission along adjacent boundary. Furthermore, a cosine-shape isolated band exhibits, supporting the topological Bloch oscillation in the frequency dimension under the effective constant force, which is localized at the spatial boundary and shows the topological feature. Our work therefore points out further capability of light transmission under topological protections in both spatial and spectral regimes, and provides future on-chip applications in the lithium niobate platform.

physics.optics↗

arXiv2021

Photon retention in coherently excited nitrogen ions

Quantum coherence in quantum optics is an essential part of optical information processing and light manipulation. Alkali metal vapors, despite the numerous shortcomings, are traditionally used in quantum optics as a working medium due to convenient near-infrared excitation, strong dipole transitions and long-lived coherence. Here, we proposed and experimentally demonstrated photon retention and subsequent re-emittance with the quantum coherence in a system of coherently excited molecular nitrogen ions (N2+) which are produced using a strong 800 nm femtosecond laser pulse. Such photon retention, facilitated by quantum coherence, keeps releasing directly-unmeasurable coherent photons for tens of picoseconds, but is able to be read-out by a time-delayed femtosecond pulse centered at 1580 nm via two-photon resonant absorption, resulting in a strong radiation at 329.3 nm. We reveal a pivotal role of the excited-state population to transmit such extremely weak re-emitted photons in this system. This new finding unveils the nature of the coherent quantum control in N2+ for the potential platform for optical information storage in the remote atmosphere, and facilitates further exploration of fundamental interactions in the quantum optical platform with strong-field ionized molecules.

quant-ph↗