arXiv subjects

Polina Sharapova

Publications and source records attributed to Polina Sharapova.

6 recordsLinked to original sources

arXiv2026

Multimode squeezed light generation and characterization

Nowadays, the realization of quantum computations and communications based on continuous variables has attracted a significant attention due to a substantial expansion of the system dimensionality. The main progress in this area is attributed to the implementation of multimode systems based on squeezed states of light. One of the simplest ways to generate such states relies upon their producing in a single-pass optical parametric amplifier (OPA) using ultrafast pumping. However, for homodyne detection of such multimode states, the profile of the local oscillator (LO) must perfectly match the profile of the measured mode. Usually, this is not the case; therefore a proper treatment of multimode squeezing is required. In this work, we study both theoretically and experimentally the multimode squeezed light generated in type-0 and type-II OPA. We characterize such sources and investigate the degree of squeezing in dependence on the LO spectral profile, employing a pulse shaping technique. The theoretical analysis is performed using the Schmidt-mode theory. This work might have a significant impact on the realization of multimode quantum protocols

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arXiv2026

An ultra-bright, highly-scalable, squeezed light source for hybrid quantum photonics

Hybrid quantum photonics seeks to combine the complementary advantages of continuous- and discrete-variable quantum optics. This typically entails photon-counting measurements on entangled states generated by interfering many single-mode squeezed-vacuum (SMSV) states. However, because conventional photon-counting schemes are mode-insensitive, it is critical that the SMSV states occupy a single, well-defined mode. Achieving this requires careful engineering of the process, which determines both the spatial and spectro-temporal properties of the generated state. In addition, the ideal source must be massively scalable, capable of efficiently generating strong squeezing, and remain compatible with existing detection schemes and fiber networks. Although many platforms address one or more of these requirements, satisfying all of them simultaneously remains challenging. Here, we present a source that meets all of these requirements: a single-pass, periodically poled, Type-II potassium titanyl phosphate (KTP) waveguide optimized for scalable hybrid quantum-photonic architectures. The SMSV state produced by the source has a measured effective mode number of 1.24. Furthermore, the source is extremely bright (producing up to 40 000 photons per pulse) and operates at a central wavelength of 1546nm, optimized for fiber-network compatibility and which, in combination with picosecond duration, also enables intrinsic photon-number resolution in superconducting nanowire single-photon detectors. Although this source constitutes an ideal source in a simplified picture, the ultimate limitations of any source will be governed by complex dynamics that arise when the system is driven at high-gain or due to unavoidable loss during state generation. We have therefore developed a complete theoretical framework that enables a comprehensive photon-counting-based characterization of the source.

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arXiv2026

Gain-induced spectral non-degeneracy in type-II parametric down-conversion

We demonstrate the novel effect of gain-induced spectral shifts in the type-II parametric down-conversion (PDC) process, which results in a transition from degenerate to non-degenerate PDC with increasing parametric gain. This effect, originating from the second-order dispersion terms, significantly alters the properties of PDC in the high-gain regime, where it leads to increased distinguishability of the generated photon pairs. The effect is established by evaluating a rigorous theoretical model, which is based on solving a system of coupled integro-differential equations for monochromatic operators. The widely used spatially-averaged approximate model fails to reproduce this important effect.

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arXiv2024

Simultaneous measurement of multimode squeezing

Multimode squeezed light is an increasingly popular tool in photonic quantum technologies, including sensing, imaging, and computation. Meanwhile, the existing methods of its characterization are technically complicated, and in the best case, deal with a single mode at a time. Here, we demonstrate experimentally how the squeezing can be measured in multiple spatial modes simultaneously, using optical parametric amplification and direct detection followed by modal decomposition based on spatial intensity correlations. We apply this method to a multimode squeezed vacuum generated via high-gain parametric down-conversion. We measure the degrees of squeezing and anti-squeezing for eight strongest spatial modes, obtaining highest squeezing and anti-squeezing values of $-5.2 \pm 0.2$ dB and $8.6 \pm 0.3$ dB, respectively.

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arXiv2024

Nonlinear squeezing generation via multimode PDC and single photon measurement

Nonlinear squeezing is a property of non-Gaussian states of light with an important application in continuous variable quantum computing. We study the generation of nonlinear squeezing in multimode systems produced by the photon-added coherent state technique. We present a protocol and find a regime in which the nonlinear squeezing appears in two modes simultaneously, even for a weak non-Gaussianity induced by the single-photon addition. We explore the properties of nonlinear squeezing depending on the modal structure of light, as well as the seed and local oscillator profiles, and present an optimal measurement strategy.

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arXiv2020

Managing spectral properties and Schmidt mode content of squeezed vacuum light using sum-frequency converter

Capabilities of quantum optical SFG-gate seeded by squeezed light are investigated in the frame of frequency Schmidt modes. Methods to manage and manipulate extensively the properties and mode content of squeezed light are developed. Possibilities to block and select any certain Schmidt mode of squeezed light with conservation of non-classical properties are demonstrated. The significant phase sensitivity of the gate is shown and the ways to manage the spectral distribution of the output light due to the phase effects and variable coupling between modes in the gate are demonstrated. The effect of swapping between modes in the gate is found. It allows to enhance squeezed light in a set of modes without loss of photon correlations which is important for further experiments and new applications.

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