Andrii Sokolov

Bio: Andrii Sokolov is an academic researcher from University College Dublin. The author has contributed to research in topics: Qubit & Quantum computer. The author has an hindex of 4, co-authored 15 publications receiving 45 citations.

A Single-Electron Injection Device for CMOS Charge Qubits Implemented in 22-nm FD-SOI

Abstract: This letter presents a single-electron injection device for position-based charge qubit structures implemented in 22-nm fully depleted silicon-on-insulator CMOS. Quantum dots are implemented in local well areas separated by tunnel barriers controlled by gate terminals overlapping with a thin 5-nm undoped silicon film. Interface of the quantum structure with classical electronic circuitry is provided with single-electron transistors that feature doped wells on the classic side. A small $0.7\times 0.4\,\,\mu \text{m}^{2}$ elementary quantum core is co-located with control circuitry inside the quantum operation cell which is operating at 3.5 K and a 2-GHz clock frequency. With this apparatus, we demonstrate a single-electron injection into a quantum dot.

Modelling and Verification of Nonlinear Electromechanical Coupling in Micro-Scale Kinetic Electromagnetic Energy Harvesters

Abstract: Electromechanical coupling in kinetic energy harvesters is the key aspect of these devices that ensures an effective energy conversion process. When modelling and designing such devices, it is necessary to incorporate electromechanical coupling correctly since it will determine the amount of energy that will be converted during its operation. As the engineering community prefers compact (lumped) models of such devices, the conventional choice of the lumped model for the electromagnetic type of electromechanical coupling is linear damping, proportional to the velocity of the mechanical resonator in a harvester, leading to the idea of maximizing the velocity in order to improve the energy conversion process. In this paper, we show that electromechanical coupling in electromagnetic kinetic energy harvesters is inherently nonlinear and requires a number of aspects to be taken into account if one wants to optimize a device. We show that the proposed model, which is based on first principles of electromagnetics, can be reduced to a nonlinear lumped model that is particularly convenient for analysis and design. The modelling approach and the resulting lumped model are verified using two MEMS electromagnetic harvesters operating over a range of frequencies from 300 to 500 Hz (Harvester A) and from 50 to 70 Hz (Harvester B) generating from mV (Harvester A) to few volts (Harvester B) of RMS voltage, respectively. The proposed modelling approach is not limited to energy harvesters but can also be applied to magnetic sensors or other MEMS devices that utilise electromagnetic transduction.

Position-Based CMOS Charge Qubits for Scalable Quantum Processors at 4K

Abstract: We describe a quantum computing hardware paradigm that exploits the current scaling achievements of mainstream CMOS technology. Just like in a small IC chip, where a single nanometer-sized CMOS transistor can be reliably replicated millions of times to build a digital processor, we propose a new structure of a qubit realized as a CMOS-compatible charge-based quantum dot that can be reliably replicated thousands (or perhaps even millions) of times to construct a quantum processor. Combined with an on-chip CMOS controller, it will realize a useful quantum computer (QC) that can operate at 4 K, which is much higher than the temperature of today's QCs of 15 mK.

CMOS charge qubits and qudits: entanglement entropy and mutual information as an optimization method to construct CNOT and SWAP gates

Abstract: In this paper, we propose an optimization method for the construction of two-qubit and two-qudit quantum gates based on semiconductor position-based charge qubits. To describe the evolution of various quantum states, we use a Hubbard based model and Lindblad formalism. The suggested optimization algorithm uses the time evolution of entanglement entropy and mutual information for the determination of the system parameters to achieve high fidelity gates.

Simulation Methodology for Electron Transfer in CMOS Quantum Dots

Abstract: The construction of quantum computer simulators requires advanced software which can capture the most significant characteristics of the quantum behavior and quantum states of qubits in such systems. Additionally, one needs to provide valid models for the description of the interface between classical circuitry and quantum core hardware. In this study, we model electron transport in semiconductor qubits based on an advanced CMOS technology. Starting from 3D simulations, we demonstrate an order reduction and the steps necessary to obtain ordinary differential equations on probability amplitudes in a multi-particle system. We compare numerical and semi-analytical techniques concluding this paper by examining two case studies: the electron transfer through multiple quantum dots and the construction of a Hadamard gate simulated using a numerical method to solve the time-dependent Schrodinger equation and the tight-binding formalism for a time-dependent Hamiltonian.

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

About Les Houches

Abstract: Maurice Jacob was a student in ’55, a session organizer in ’65, a lecturer in ’71, and the organizer of the Les Houches LEP Summer Study, in ’78. He was a member of the board from the mid seventies to the mid eighties.

Knowledge structuring for enhancing mechanical energy harvesting (MEH): An in-depth review from 2000 to 2020 using CiteSpace

Abstract: Due to swift innovations in mechanical energy harvesting (MEH) during recent years, the findings of MEH research are prolific. The objective of the recent study is to visualise the development trends and the current research status of MEH by conducting a bibliometric analysis using CiteSpace. The original articles published between 2000 and 2020 were collected from the Web of Science core collection (WOSCC) using an advanced keyword search related to MEH. Then, the visualisation networks of author co-authorship, institution co-authorship, and country co-authorship analyses were engendered to categorise the productive authors, institutions, and countries, correspondingly. Furthermore, the core journals, the top research articles and the most significant authors were determined by visualising the journal co-citation, document co-citation and the author co-citation networks, respectively. The keywords co-occurrence analysis was performed to highlight the current hot research topics and new research frontiers, whereas cluster analysis showed the knowledge structure and core subject categories. The investigation explored the major contributing bodies of MEH research at micro, meso and macro levels, the degree of collaboration among them and the knowledge sources of MEH. The main research areas, the current knowledge status and hotspots of MEH were detected for future research. Furthermore, the analysis of grants and collaborating countries reveals that the policy support of People R. China, the United States of America (USA), England and South Korea is significantly favourable to promote the development of MEH research. Finally, the comparison analysis was performed for various modes of energy harvesting and the practical applications of energy harvesting technologies in the real world were highlighted.

Number-Resolved Photocounter for Propagating Microwave Mode

Abstract: Detecting the presence of photons in a propagating microwave mode has been demonstrated only recently, and an important tool still missing is a photocounter able to determine in a single shot the number of photons in an incoming mode. The authors create such a photocounter by catching an incoming wave packet in a stationary mode, and then measuring the photon number of that mode bit by bit, using an ancillary qubit. Additionally, this device can measure the envelope of the incoming wave packet $i\phantom{\rule{0}{0ex}}n$ $s\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}u$. Beyond its direct applications in quantum sensing, this photocounter allows development of quantum information protocols that benefit from real-time feedback based on photon number.