Browsing by Author "Raasakka, Matti"

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  • Addressing Risks in Artificial Intelligence Act and in Future Quantum Computing Legislation
    (2024-09-06) Korpimaki, Ilari
     Perustieteiden korkeakoulu | Bachelor's thesis
    Artificial intelligence (AI) and quantum computing (QC) are two trans-formative technologies with the potential to reshape global public policies. Although distinct, both face similar regulatory challenges, particularly in data protection, national stability, and market power. Major corporations and geopolitical competition drive their development, making effective regulation essential. In response to this need, this thesis explores the intersection of artificial intelligence and quantum computing, focusing on their similarities and associated risks. The research aims to determine how the EU Artificial Intelligence Act (AIA) addresses various risks and to apply these insights to future EU regulation of quantum computing. To achieve this, a state-of-the-art literature review was conducted, examining the current development and potential challenges of both technologies. The findings aim to provide a foundation for developing effective quantum computing regulations.
  • Automatic Hardware-aware Optimization of Fault-tolerant Quantum Circuits
    (2024-04-26) Do, Huyen
     Perustieteiden korkeakoulu | Bachelor's thesis
    This thesis explores the calibration of quantum error correction codes (QECC) by focusing on optimizing plaquette circuits at the native gate level and assessing their error rates on real quantum hardware. The research underscores the importance of native gate optimization to boost the performance and reliability of quantum computations. A crucial part of the study involves experiments on the repetition of plaquette circuits using two ancilla qubit configurations: Type A, involving fresh ancilla qubits for each repetition, and Type B, reusing ancilla qubits. Based on the data collected, an error model was formulated. A significant result is that the error rate for a single plaquette operation using IonQ’s Aria1 Quantum Processing Unit (QPU) was 1.5%, surpassing the essential 1% threshold for effective quantum error correction, thus indicating a need for further improvements. The thesis also demonstrates the variability in QECC implementation across different quantum architectures, emphasizing the challenges in establishing universally applicable error rates. The study proposes to extend this research to evaluate the error rates of plaquette circuits on other types of quantum hardware, such as superconducting quantum computers. Future work will develop a broader understanding of QECC’s effective implementation across various quantum computing platforms, enhancing the robustness and scalability of quantum error correction methods.
  • Characterisations of classical orthogonal polynomials
    (2022-09-06) Himanen, Jarno
     Perustieteiden korkeakoulu | Bachelor's thesis
  • Characterising a Superconducting Nanobolometer for Infrared Photon Detection
    (2023-09-07) da Silva Rossetto, Iago
     Perustieteiden korkeakoulu | Bachelor's thesis
  • Classical Simulation of Quantum Computers
    (2022-05-15) Kähkönen, Markus
     Sähkötekniikan korkeakoulu | Bachelor's thesis
  • A Comparative Study of Classical and Quantum Transformer Models and Their Applications
    (2024-09-29) Shah, Jayaditya
     Perustieteiden korkeakoulu | Bachelor's thesis
    Transformers are a neural network architecture that enable the utilisation of a larger context frame than traditional neural networks when training deep learning models. With the advent of the ongoing decade, transformers have enabled the application of large language models, improved computer vision, generative models and other large-scale artificial intelligence systems. This thesis investigates the potential of quantum transformers to implement deep learning tasks focusing on the Quixer model, developed by Quantinuum, by comparing a classically simulated version of Quixer to classical transformers. The thesis is motivated by the need to optimize transformer components for large-scale applications, to address the quadratic complexity arising from the self attention mechanism. The results of the thesis indicate that Quixer performs in line with the classical baseline as published in the paper by Quantinuum when reproduced with the same dataset, and model performance follows the trend for another dataset of twice the size. Hence, providing a proof of concept quantum transformers can be considered an effective method for developing large-scale models in the future with the eventual improvement of quantum hardware.
  • Comparing resource requirements of noisy quantum simulation algorithms for the Tavis–Cummings model
    (2024-01-23) Haukisalmi, Alisa
     Perustieteiden korkeakoulu | Master's thesis
    Fault-tolerant quantum computers could facilitate the simulation of quantum systems unfeasible for classical computation via Trotterization, a systematic way of implementing time-evolution operators of qubit Hamiltonians as quantum circuits. Pre-fault-tolerance, however, one must make do with noisy intermediate-scale quantum (NISQ) devices, which cannot by themselves manage the deep circuits required by Trotterization. The utilisation of NISQ devices then calls for the use of additional strategies, which include quantum error mitigation (QEM) for alleviating device noise, and variational quantum algorithms (VQAs) which combine classical optimization with short-depth, parameterized quantum circuits. This thesis compares two such methods: zero-noise extrapolation (ZNE) with noise amplification by circuit folding, and incremental structural learning (ISL), a type of circuit recompiling VQA. These are applied to Trotterized time-evolution of the Tavis–Cummings model (TCM) under a noise simulation. Since both methods add circuit evaluation overhead, it is of interest to see how they compare both in the accuracy of the dynamics they produce, and in terms of the quantum resources used. Additionally, noisy recompilation of time-evolution circuits with ISL has not previously been explored. The comparison is done for various simulation parameters, such as the TCM system size. We find that while ISL achieves lower error than ZNE for smaller system sizes, it fails to produce correct dynamics for 4 qubits, where ZNE is superior. Diverging resource requirements for ISL and ZNE are observed, with ISL achieving low circuit depths at the cost of a large number of circuit evaluations. These results highlight the importance of considering the performance of VQAs under noisy conditions as well.
  • Computational Analysis of Plasmonic Surfaces
    (2024-09-06) Witwiyaruj, Narat
     Perustieteiden korkeakoulu | Bachelor's thesis
  • Control Device for the Reconfigurable Photonic Integrated Circuit Devices
    (2023-04-28) Eliutin, Kirill
     Perustieteiden korkeakoulu | Bachelor's thesis
  • Correlated Photons for Advanced Imaging Applications
    (2023-04-28) Baltasheva, Yerkezhan
     Perustieteiden korkeakoulu | Bachelor's thesis
  • Coupling with One and Two Qubit Couplers
    (2024-04-26) Paukkunen, Lari
     Perustieteiden korkeakoulu | Bachelor's thesis
    In recent years, the research in quantum electrodynamics has rocketed, as the interest in quantum computing has increased. In pursuit of quantum supremacy, there is still need for the current procedures to be improved. The typical quantum computing architectures require tunable coupling between the circuit elements provided by a coupler, which in most cases consists of a qubit mediating the coupling between the circuit elements. However, the current one-qubit coupler has weak coupling strength; it operates slowly by tuning the qubit frequency; and the coupling can hardly be turned off. This thesis proposes the use of a coupler consisting of two qubits instead, as it provides solutions to these issues. This thesis found the two-qubit coupler to have an effective coupling range twice as large as the one-qubit coupler. The two-qubit coupler also operates fast, as instead of tuning the frequency, the coupling is tuned by changing the coupler state. Furthermore, the two-qubit coupler allows the coupling between the circuit elements to be completely turned off. In addition, this thesis discusses the property of the two-qubit coupler to be prepared into a superposition of coupler states, which offers possibilities for interesting applications in the field of quantum electrodynamics.
  • Designing 3D Cavity For Photon Number Cooling Using Quantum Circuit Refrigerator
    (2024-04-26) Khan, Zuhair
     Perustieteiden korkeakoulu | Bachelor's thesis
    Qubits are the fundamental components of quantum computers, and 3D cavity resonators are often used to study qubits in low-noise environments. However, to achieve even lower noises, quantum circuit refrigerators (QCRs) can be used to reduce photon numbers in qubits and resonators. In this thesis, a 3D cavity resonator model is proposed for coupling to QCRs, and then the model’s performance is characterised using two physical 3D cavities, made of aluminium and copper, respectively. The performance of the 3D cavity resonator was quantified using transmission and reflection measurements from a vector network analyser (VNA), which were used to estimate the resonant frequency and quality factor. The measurements were conducted at room temperature and cryogenic temperatures, using a cryogen-free dilution refrigerator. Based on the current results, the 3D cavity resonator significantly underperforms the simulations, with the 3D cavities reaching quality factors of 67 000 and 12 000, respectively.
  • Designing a Platform for Microwaving Quantum Hall States
    (2023-04-05) Frei Nadarajah, Kristiana
     Perustieteiden korkeakoulu | Bachelor's thesis
  • Designing an Experimental Setup to Achieve Superradiance in a Two-Qubit Quantum Heat Valve
    (2024-09-05) Chowdhury, Foysal
     Perustieteiden korkeakoulu | Bachelor's thesis
    Heat is a major concern in making efficient quantum devices. In the rapidly evolving field of quantum heat transport, many devices have been proposed and realised to control the flow of heat on the quantum level. One of the most prominent device in this context is a tunable photonic heat valve. In a newly theorised model, there was a proposal of making a more enhanced tunable photonic heat valve using the concept of Superradiance. Therefore, this thesis lays down the steps to design and realise the device suggested in the model. The components of the device which includes two qubits, two coplanar waveguide resonators, two resistive heat baths, and two S-I-N-I-S junctions were designed. The qubits were designed, and simulated to fine tune the parameters. Using the feedback of the simulation, the characterising chip was fabricated. Later, the simulation results were validated, and superradiant states were established through qubit spectroscopy.
  • Dihedraalisen piilotetun aliryhmän ongelma
    (2020-10-12) Oinonen, Oona
     Perustieteiden korkeakoulu | Bachelor's thesis
  • The Effect of Circuit Structure on the Expressiveness of Quantum Neural Networks
    (2024-09-04) Tynninen, Tia-Mari
     Perustieteiden korkeakoulu | Bachelor's thesis
    As continuous advances are made in quantum computing, quantum machine learning has risen to be a prominent research area. Variational quantum algorithms, and especially their subgroup of quantum neural networks (QNNs), have emerged as promising approaches for real-life applications. Mathematically, any QNN can be presented as a partial Fourier-type series, whose terms are determined by a parametrized quantum circuit (PQC) specific to the model. Although the Fourier coefficients in this series play a pivotal role in determining the expressiveness of the model, little research has been conducted on the manner in which their values are formed. This thesis examines the coefficient distributions produced by simulating simple PQC structures, mapping and comparing any phenomena in the values of the Fourier coefficients, which notably restrict the expressiveness of the corresponding QNNs. The main focus of comparison are circuits of different shapes, but which yield the same frequencies. In addition, this thesis aims to connect distributions of coefficients displaying the same phenomena to elements in the underlying parametrized quantum circuits. This thesis investigated small QNNs, where the rotations in their data encoding and weight training blocks were chosen to be either Pauli-X, -Y, or -Z rotations. The measurement observable was chosen as the Pauli-X, -Y or -Z operator on the first qubit. For each circuit, all data encoding layers were identical amongst themselves and all weight training blocks implemented the same entangling subroutine in all their inner layers. Common factors were found in circuit structures, which restricted the corresponding model to a simple sine or a constant-valued function. The coefficients being restricted to only real or imaginary values, which further allows for writing the model as a series of cosines or sines, respectively, was found to be a common phenomena. It was also determined that the amount of inner layers in the training blocks can fundamentally alter the resulting coefficients for some circuits. However, this layer count did not seem to affect any of the distributions produced by one-qubit models. Commonly appearing differences and similarities were also found for PQCs of different shapes with the same frequency spectra. For example, patterns dependant on the parities of different factors were more frequent in models with at least two qubits.
  • The effect of quantum optimization algorithms on the performance of variational quantum factoring
    (2021-12-18) Phan, Vivian
     Perustieteiden korkeakoulu | Bachelor's thesis
  • Efficient Readout of Superconducting Qubits
    (2024-09-06) Dao, Quynh
     Perustieteiden korkeakoulu | Bachelor's thesis
    Quantum computers have the potential to revolutionize various fields, from cryptography to material science, by employing the principles of quantum mechanics. At the core of these quantum computers are quantum processors, where the ability to perform fast and reliable manipulation and readout of qubit states is crucial for their overall performance. This thesis presents a systematic approach to optimize the readout of superconducting transmon qutrits—quantum systems with three states that offer a more expansive computational space compared to traditional qubits. The study involves simulating a transmon-resonator system and exploring two key approaches: the optimization of integration weights and the use of frequency-modulated readout pulses. The first method, integration weights optimization, yielded significant improvements in the readout process, with an enhancement of up to 60%. This technique is most successful when a proper balance between pulse duration and coupling strength is maintained. However, its effectiveness diminishes as coupling between the resonator and the environment increases, with improvements becoming more limited to a narrower parameter space. In contrast, the second strategy, frequency modulation of the readout pulse, only resulted in a slight improvement under certain parameter ranges, with the best performance is in the region with high coupling and short duration. While modulated pulses can improve state distinguishability in naturally low distinguishability regimes, they require careful optimization of the modulation depth and readout frequency offset, introducing additional complexity and potential time costs in implementation.
  • Ellipsometry for Determining Near-Infrared Optical Properties of Si:Ga with Applications to Lossy Optical Waveguides
    (2022-12-16) Tasanen, Teemu
     Perustieteiden korkeakoulu | Bachelor's thesis
  • Emulating the effects of quantum noise on a Quantum Approximate Optimization Algorithms
    (2021-12-17) Andersson, Joona
     Perustieteiden korkeakoulu | Bachelor's thesis