arXiv subjects

D. Mogilevtsev

Publications and source records attributed to D. Mogilevtsev.

At least 19 recordsLinked to original sources

arXiv2025

Radio-Frequency Hong-Ou-Mandel Interference with Conditionally Built States

We report an experimental demonstration of room-temperature Hong-Ou-Mandel (HOM) interference at a radio-wave frequency of 120 MHz using conditional build-up of quantum states from classical phase-averaged coherent states. This approach enables observation of quantum effects in spectral regimes where conventional single-photon sources and detectors are unavailable or require cryogenic conditions. By constructing a high-fidelity approximation of a single-photon state with phase-averaged coherent states, we observe the normalized second-order intensity correlation dips significantly below the classical limit of 0.5. The method allows for tunable noise suppression via optimization of the state representation. Our results establish the feasibility of using conditionally prepared classical states to simulate quantum interference phenomena in the radio-frequency domain. This technique opens the door to realizing other quantum protocols, such as Bell inequality tests, in frequency ranges where standard quantum technologies are currently infeasible.

quant-ph↗

arXiv2024

Frame-filtered ghost imaging with a SPAD array used both as a multiple "bucket" detector and an imaging camera

An approach to ghost imaging with a single SPAD array used simultaneously as a several-pixel "bucket" detector and an imaging camera is described. The key points of the approach are filtering data frames used for ghost-image reconstruction by the number of per-frame counts and superposing correlation images obtained for different "bucket" pixels. The imaging is performed in an experiment with a pseudo-thermal light source where the light intensity is so low that the dark counts have a noticeable effect on imaging. We demonstrate that the approach is capable to significantly reduce the destructive effect of dark counts on the ghost image and improve image contrast, spatial resolution, and image similarity to a reference image.

physics.optics↗

arXiv2024

Evidence-based certification of quantum dimensions

Identifying a reasonably small Hilbert space that completely describes an unknown quantum state is crucial for efficient quantum information processing. We introduce a general dimension-certification protocol for both discrete and continuous variables that is fully evidence-based, relying solely on the experimental data collected and no other unjustified assumptions whatsoever. Using the Bayesian concept of relative belief, we take the effective dimension of the state as the smallest one such that the posterior probability is larger than the prior, as dictated by the data. The posterior probabilities associated with the relative-belief ratios measure the strength of the evidence provide by these ratios so that we can assess whether there is weak or strong evidence in favor or against a particular dimension. Using experimental data from spectral-temporal and polarimetry measurements, we demonstrate how to correctly assign Bayesian plausible error bars for the obtained effective dimensions. This makes relative belief a conservative and easy-to-use model-selection method for any experiment.

quant-ph↗

arXiv2024

Relative-belief inference in quantum information theory

We introduce the framework of Bayesian relative belief that directly evaluates whether or not the experimental data at hand supports a given hypothesis regarding a quantum system by directly comparing the prior and posterior probabilities for the hypothesis. In model-dimension certification tasks, we show that the relative belief procedure typically chooses Hilbert spaces that are never smaller in dimension than those selected from optimizing a broad class of information criteria, including Akaike's criterion. As a concrete and focused exposition of this powerful evidence-based technique, we apply the relative belief procedure to an important application: state reconstruction of imperfect quantum sources. In particular, just by comparing prior and posterior probabilities based on data, we demonstrate its capability of tracking multiphoton emissions using (realistically lossy) single-photon detectors in order to assess the actual quality of photon sources without making ad hoc assumptions, thereby reliably safeguarding source integrity for general quantum-information and communication tasks with Bayesian reasoning. Finally, we discuss how relative belief can be exploited to carry out parametric model certification and estimate the total dimension of the quantum state for the combined (measured) physical and interacting external systems described by the Tavis--Cummings model.

quant-ph↗

arXiv2023

Optimizing mixing in the Rudner-Levitov lattice

Here we discuss optimization of mixing in finite linear and circular Rudner-Levitov lattices, i.e., Su-Schrieffer-Heeger lattices with a dissipative sublattice. We show that presence of exceptional points in the systems spectra can lead to drastically different scaling of the mixing time with the number of lattice nodes, varying from quadratic to the logarithmic one. When operating in the region between the maximal and minimal exceptional points, it is always possible to restore the logarithmic scaling by choosing the initial state of the chain. Moreover, for the same localized initial state and values of parameters, a longer lattice might mix much faster than the shorter one. Also we demonstrate that an asymmetric circular Rudner-Levitov lattice can preserve logarithmic scaling of the mixing time for an arbitrary large number of lattice nodes.

quant-ph↗

arXiv2023

Anomalous transport in periodic photonic chains with designed loss

Here we show that a coherent random walk in a perfectly periodic chain of bosonic modes with designed loss can exhibit a variety of different anomalous transfer regimes in dependence on the initial state of the chain. In particular, for any given finite initial time-interval there is a set of initial states leading to a hyperballistic transport regime. Also, there are initial states allowing one to achieve a subdiffusive regime or even localization for a given time-interval, or change an asymptotic long-time diffusion rate. We show how these anomalous transport regimes can be practically realized in a laser-written network of single-mode waveguides in balk glass or how a planar system of coupled single-mode waveguides can be realized with an integrated photonic platform.

physics.optics↗

arXiv2022

Emulation of quantum measurements with mixtures of coherent states

We propose a methodology to emulate quantum phenomena arising from any non-classical quantum state using only a finite set of mixtures of coherent states. This allows us to successfully reproduce well-known quantum effects using resources that can be much more feasibly generated in the laboratory. We present a simple procedure to experimentally carry out quantum-state emulation with coherent states, illustrate it emulating multi-photon NOON states with few phase-averaged coherent states, and demonstrate its capabilities in observing fundamental quantum-mechanical effects, such as the Hong-Ou-Mandel effect, violating Bell inequalities and witnessing quantum non-classicality.

quant-ph↗

arXiv2022

Breaking reciprocity by designed loss

In this paper we show how designed loss in open quantum systems can break reciprocity of the state propagation, and how the non-reciprocal and even unidirectional propagation can be achieved for different kinds of designed loss, both linear and nonlinear ones. In particular, we show how a unidirectional propagation can be achieved for states of certain symmetry in linear schemes, demonstrate possibility of building a single-mode optical insulator by combining two kinds of nonlinear designed losses, and the way to build non-reciprocal circulator with a planar structure of dissipatively coupled waveguides. We discuss feasibility of the considered schemes and suggest possible realizations.

quant-ph↗

arXiv2021

Integrated source of path-entangled photon pairs with efficient pump self-rejection

We present a scheme for an integrated four-wave mixing source of narrow-band path-entangled photon pairs with efficient spatial pump self-rejection. The scheme is based on correlated loss in a system of waveguides in Kerr nonlinear media. We demonstrate that this setup allows for upwards of 100dB pump rejection, without additional filtering. The effect is reached by driving the symmetric collective mode that is strongly attenuated by an engineered dissipation, while photon pairs are born in the antisymmetric mode. A similar set-up can additionally be realized for generation of two-photon NOON states, also with pump self-rejection. We discuss implementation of the scheme by means of the coherent diffusive photonics, and demostrate its feasibility both in glass (such as fused silica-glass and IG2), and planar semiconductor waveguide structures in indium phosphide (InP) and in silicon.

quant-ph↗

arXiv2021

Gravitational dephasing in spontaneous emission of atomic ensembles in timed Dicke states

Here we discuss an effect of dephasing induced by a weak gravitational field on the collective radiation dynamics of an atomic system in timed single-photon Dicke states. We show that a photon absorbed by the stationary system of randomly placed stationary atoms is no longer spontaneously emitted in the direction of the impinging photon. Gravity leads to broadening of the angular distribution of emission.

quant-ph↗

arXiv2021

Lost photon enhances superresolution

Quantum imaging can beat classical resolution limits, imposed by diffraction of light. In particular, it is known that one can reduce the image blurring and increase the achievable resolution by illuminating an object by entangled light and measuring coincidences of photons. If an $n$-photon entangled state is used and the $n$th-order correlation function is measured, the point-spread function (PSF) effectively becomes $\sqrt n$ times narrower relatively to classical coherent imaging. Quite surprisingly, measuring $n$-photon correlations is not the best choice if an $n$-photon entangled state is available. We show that for measuring $(n-1)$-photon coincidences (thus, ignoring one of the available photons), PSF can be made even narrower. This observation paves a way for a strong conditional resolution enhancement by registering one of the photons outside the imaging area. We analyze the conditions necessary for the resolution increase and propose a practical scheme, suitable for observation and exploitation of the effect.

quant-ph↗

arXiv2020

Optimal correlation order in super-resolution optical fluctuation microscopy

Here, we show that, contrary to the common opinion, the super-resolution optical fluctuation microscopy might not lead to ideally infinite super-resolution enhancement with increasing of the order of measured cumulants. Using information analysis for estimating error bounds on the determination of point sources positions, we show that reachable precision per measurement might be saturated with increasing of the order of the measured cumulants in the super-resolution regime. In fact, there is an optimal correlation order beyond which there is practically no improvement for objects of three and more point sources. However, for objects of just two sources, one still has an intuitively expected resolution increase with the cumulant order.

quant-ph↗

arXiv2019

Avalanche-like behavior of up-conversion luminescence by nonlinear coupling of pumping rates

Here we report and discuss the avalanche-like up-conversion behavior in absence of the avalanche. We experimentally observed significant changes in the slope of the curve for the intensity dependence of up-conversion luminescence of erbium ions in green band on the pump intensity of the diode laser. Such changes are typical for the photon avalanche. However, the concentration of erbium ions is insufficient for an efficient exchange of energy between them, and excitation of a photon avalanche is not possible. Using a simple three-level approximation of the up-conversion process model, we have shown that the observed avalanche-like luminescence process can also occur in the absence of a photon avalanche due to the non-linear relation between the efficiency of two pumping channels of erbium ion caused by intensity dependence of the absorption.

physics.optics↗

arXiv2019

Reconstructing compound objects by quantum imaging with higher-order correlation functions

Quantum imaging has a potential of enhancing precision of the object reconstruction by using quantum correlations of the imaging field. This is especially important for imaging requiring low-intensity fields up to the level of few-photons. However, quantum imaging generally leads to nonlinear estimation problems. The complexity of these problems rapidly increases with the number of parameters describing the object. We suggest a way to drastically reduce the complexity for a wide class of problems. The key point of our approach is connecting the features of the Fisher information with the parametric locality of the problem, and building the efficient iterative inference scheme reconstructing only a subset of the whole set of parameters in each step. This iterative scheme is linear on the total number of parameters. This scheme is applied to quantum near-field imaging, the inference procedure is developed resulting in super-resolving reconstruction of grey compound transmission objects. The functionality of the method is demonstrated with experimental data obtained by measurements of higher-order correlation functions for imaging with entangled twin-photons and pseudo-thermal light sources. By analyzing the informational content of the measurement, it becomes possible to predict the existence of optimal photon correlations providing for the best image resolution in the super-resolution regime. This prediction is experimentally confirmed. It is also shown how an estimation bias stemming from image features may drastically improve the resolution.

quant-ph↗

arXiv2019

Quantum noise radar: superresolution with quantum antennas by accessing spatiotemporal correlations

We suggest overcoming the "Rayleigh catastrophe" and reaching superresolution for imaging with both spatially and temporally-correlated field of a superradiant quantum antenna. Considering far-field radiation of two interacting spontaneously emitting two-level systems, we show that for the measurement of the temporally-delayed second-order correlation function of the scattered field, the Fisher information does not tend to zero with diminishing the distance between a pair of scatterers even for non-sharp time-averaged detection. For position estimation of a larger number of scatterers, measurement of the time-delayed function is able to provide a considerable accuracy gain over the zero-delayed function. We show also that the superresolution with the considered quantum antenna can be achieved for both near-field imaging and estimating parameters of the antenna.

quant-ph↗

arXiv2018

Restoring Heisenberg limit via collective non-Markovian dephasing

In this work an exactly solvable model of N two-level systems interacting with a single bosonic dephasing reservoir is considered to unravel the role played by collective non-Markovian dephasing. We show that phase estimation with entangled states for this model can exceed the standard quantum limit and demonstrate Heisenberg scaling with the number of atoms for an arbitrary temperature. For a certain class of reservoir densities of states decoherence can be suppressed in the limit of large number of atoms and the Heisenberg limit can be restored for arbitrary interrogation times. We identify the second class of densities when the Heisenberg scaling can be restored for any finite interrogation time. We also find the third class of densities when the standard quantum limit can be exceeded only on the initial stage of dynamics in the Zeno-regime.

quant-ph↗

arXiv2017

Shaping field correlations with quantum antennas

Quantum antennas can shape the spatial entanglement of emitted photons originating from specific initial non-Dicke entangled states of antenna emitters. In contrast to a classical antenna, a quantum antenna might not be affecting the amplitudes and intensities distribution of the field, but only shaping the second and higher order correlations. The shape and directivity of the correlations can be optimized using quantum state inference techniques. The character of the correlations can also be controlled by changing both the geometry and the initial state of the antenna. Positive and negative correlated twin-photons, as well as multi-photons entangled states can be produced from the same antenna for different initial states of the emitters. Our approach to antenna design can find applications in imaging and high-precision sensing, as well as in the development of an emitter-field interface for quantum information processing.

quant-ph↗

arXiv2016

Diffusive lossless energy and coherence transfer by noisy coupling

Here we show that noisy coupling can lead to diffusive lossless energy transfer between individual quantum systems retaining a quantum character leading to entangled stationary states. Coherence might flow diffusively while being summarily preserved even when energy exchange is absent. Diffusive dynamics persists even in the case when additional noise suppresses all the unitary excitation exchange: arbitrarily strong local dephasing, while destroying quantum correlations, is not affecting energy transfer.

quant-ph↗