The thesis examines the methods for determining practical quantum supremacy boundaries. This task is designed to demonstrate the existence of supremacy for specific cases. The original part involves implementation of a cold-atom quantum computer emulator, developing a realistic noise model, and conducting mathematical modeling to determine the supremacy boundary for promising quantum computers of this type. The dynamics of the quantum register state under the influence of various types of errors is also studied. As a result, it was demonstrated that quantum supremacy for quantum computers with this type of hardware architecture is achievable with only a few dozen qubits in the register. These values are realistic and quite feasible in practice.
Download (in Russian)The following objectives were stated in this graduate thesis:
The thesis goal was to develop a method for creation of ordered single-atom arrays with arbitrary configuration.
Download (in Russian)The thesis examines the methods for creating and characterizing linear optical converters based on integrated photonics. An integrated photonic device capable of converting photonic states is studied theoretically and experimentally, the device's capabilities are tested, and methods for efficient control are developed.
Download (in Russian)The thesis examines the application of Bayesian statistical methods for the problem of quantum process tomography. The goal was to implement an adaptive Bayesian process tomography algorithm with subsequent application for experimental tomography of polarization transformation in integrated optical chips.
Download (in Russian)The thesis presents a review of articles devoted to controlling the angular spectrum of SPDC biphotons by generating a pump beam in spatial transverse Hermite—Gauss and Laguerre—Gauss modes. Special attention is given to focusing the pump beam into the crystal and its influence on the number of modes generated in spontaneous parametric down conversion. The original part discusses the experiment to study cross-correlations between the spatial modes of signal and idler photons in the Hermite—Gauss basis, including the transformation of the pump mode into lower Hermite—Gauss modes with subsequent generation of Bell states based on the photon's spatial degrees of freedom.
Download (in Russian)The thesis is devoted to the experimental implementation of an adaptive Bayesian tomography protocol. The algorithm allows tomography of high-dimensional states. The experimental implementation was conducted for four-dimensional systems (ququarts). The ququart is the polarization state of a photon pair produced during spontaneous parametric down conversion (SPDC) in two nonlinear crystals with mutually perpendicular axes.
Download (in Russian)One of the fundamental problems in modern physics is control of quantum system parameters. There are many quantum systems of diverse natures, one of which is a biphoton field generated during spontaneous parametric down conversion. The problems involving a biphoton field require precise control of its spectral characteristics, the task of finding a method for controlling the frequency spectrum of a biphoton field arises. In the review part, the main methods for broadening the frequency spectrum of a biphoton field are presented, as well as the main tasks requiring the use of a biphoton field with a broad spectrum. In the original thesis section, a new method for creating a biphoton field with a broad frequency spectrum concentrated in a single angular mode is proposed.
Download (in Russian)The thesis reviews and systematizes currently existing methods for controlling the biphoton spectrum, as well as it explores the spectrum broadening possibilities by the crystal nonuniform heating where biphotons are generated through SPDC. In conclusion, the thesis demonstrates the advantages and disadvantages of the given method compared to the previously implemented ones.
Download (in Russian)The thesis goal is to develop methods for experimental preparation of arbitrary four-level quantum systems states (ququarts). Two-mode biphoton polarization states were used to realize ququarts experimentally. The proposed methods have found their application in the deterministic quantum key distribution protocol implementation.
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