Karabacak, Özkan

Profile Picture
Profile URL
https://hdl.handle.net/20.500.12469/6165
Name Variants
Karabacak O.
Ozkan, Karabacak
Karabacak,Ozkan
Karabacak,O.
Karabacak Ö.
Karabacak, Özkan
Karabacak, Ozkan
Karabacak, ÖZKAN
O. Karabacak
K.,Ozkan
Özkan Karabacak
ÖZKAN KARABACAK
K., Özkan
Karabacak,Ö.
Karabacak, O.
Karabacak, Ö.
KARABACAK, ÖZKAN
Ö. Karabacak
K., Ozkan
KARABACAK, Özkan
Ozkan Karabacak
Özkan KARABACAK
Job Title
Doç. Dr.
Email Address
[email protected]
Main Affiliation
Mechatronics Engineering
Status
Current Staff
Website
ORCID ID
0000-0002-8350-193
Scopus Author ID
24824407000
Turkish CoHE Profile ID
Google Scholar ID
WoS Researcher ID
AGX-7234-2022

Sustainable Development Goals

SDG data is not available
Documents

30

Citations

300

h-index

11

Go to Scopus profile
Documents

7

Citations

66

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Scholarly Output

7

Articles

3

Views / Downloads

61/0

Supervised MSc Theses

0

Supervised PhD Theses

0

WoS Citation Count

12

Scopus Citation Count

14

WoS h-index

2

Scopus h-index

3

Patents

0

Projects

0

WoS Citations per Publication

1.71

Scopus Citations per Publication

2.00

Open Access Source

3

Supervised Theses

0

JournalCount
2024 International Conference on Quantum Computing and Engineering -- SEP 15-20, 2024 -- Montreal, CANADA1
22nd World Congress of the International Federation of Automatic Control (IFAC) -- JUL 09-14, 2023 -- Yokohama, JAPAN1
24th International Conference on Computational Science (ICCS) -- JUL 02-04, 2024 -- Univ Malaga, Malaga, SPAIN1
Chaos Solitons & Fractals1
Future Generation Computer Systems-The International Journal of Grid Computing-Theory Methods and Applications1
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Scholarly Output Search Results

Now showing 1 - 7 of 7
  • Thumbnail Image
    Conference Object
    Citation - WoS: 1
    Citation - Scopus: 2
    Weighted Feedback-Based Quantum Algorithm for Excited States Calculation
    (IEEE Computer Soc, 2024) Rahman, Salahuddin Abdul; Karabacak, Ozkan; Wisniewski, Rafal
    Drawing inspiration from the Lyapunov control technique for quantum systems, feedback-based quantum algorithms have been proposed for calculating the ground states of Hamiltonians. In this work, we consider extending these algorithms to tackle calculating excited states. Inspired by the weighted subspace-search variational quantum eigensolver algorithm, we propose a novel weighted feedback-based quantum algorithm for excited state calculation. We show that depending on how we design the weights and the feedback law, we can prepare the pth excited state or lowest energy states up to the pth excited state. Through an application in quantum chemistry, we show the effectiveness of the proposed algorithm, evaluating its efficacy via numerical simulations.
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    Conference Object
    Citation - WoS: 5
    Citation - Scopus: 5
    Measurement-Based Control for Minimizing Energy Functions in Quantum Systems
    (Elsevier, 2023) Clausen, Henrik Glavind; Rahman, Salahuddin Abdul; Karabacak, Ozkan; Wisniewski, Rafal
    In variational quantum algorithms (VQAs), the most common objective is to find the minimum energy eigenstate of a given energy Hamiltonian. In this paper, we consider the general problem of finding a sufficient control Hamiltonian structure that, under a given feedback control law, ensures convergence to the minimum energy eigenstate of a given energy function. By including quantum non-demolition (QND) measurements in the loop, convergence to a pure state can be ensured from an arbitrary mixed initial state. Based on existing results on strict control Lyapunov functions, we formulate a semidefinite optimization problem, whose solution defines a non-unique control Hamiltonian, which is sufficient to ensure almost sure convergence to the minimum energy eigenstate under the given feedback law and the action of QND measurements. A numerical example is provided to showcase the proposed methodology. Copyright (c) 2023 The Authors. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/)
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    Article
    Feedback-Based Quantum Strategies for Constrained Combinatorial Optimization Problems
    (Elsevier, 2026) Rahman, Salahuddin Abdul; Karabacak, Ozkan; Wisniewski, Rafal
    Feedback-based quantum algorithms have recently emerged as potential methods for approximating the ground states of Hamiltonians. One such algorithm, the feedback-based algorithm for quantum optimization (FALQON), is specifically designed to solve quadratic unconstrained binary optimization problems. Its extension, the feedback-based algorithm for quantum optimization with constraints (FALQON-C), was introduced to handle constrained optimization problems with equality and inequality constraints. In this work, we extend the feedback-based quantum algorithms framework to address a broader class of constraints known as invalid configuration (IC) constraints, which explicitly prohibit specific configurations of decision variables. We first present a transformation technique that converts the constrained optimization problem with invalid configuration constraints into an equivalent unconstrained problem by incorporating a penalizing term into the cost function. Then, leaning upon control theory, we propose an alternative method tailored for feedback-based quantum algorithms that directly tackles IC constraints without requiring slack variables. Our approach introduces a new operator that encodes the optimal feasible solution of the constrained optimization problem as its ground state. Then, a controlled quantum system based on the Lyapunov control technique is designed to ensure convergence to the ground state of this operator. Two approaches are introduced in the design of this operator to address IC constraints: the folded spectrum approach and the deflation approach. These methods eliminate the need for slack variables, significantly reducing the quantum circuit depth and the number of qubits required. We show the effectiveness of our proposed algorithms through numerical simulations.
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    Conference Object
    Citation - WoS: 3
    Citation - Scopus: 3
    Adaptive Sampling Noise Mitigation Technique for Feedback-Based Quantum Algorithms
    (Springer international Publishing Ag, 2024) Rahman, Salahuddin Abdul; Clausen, Henrik Glavind; Karabacak, Ozkan; Wisniewski, Rafal
    Inspired by Lyapunov control techniques for quantum systems, feedback-based quantum algorithms have recently been proposed as alternatives to variational quantum algorithms for solving quadratic unconstrained binary optimization problems. These algorithms update the circuit parameters layer-wise through feedback from measuring the qubits in the previous layer to estimate expectations of certain observables. Therefore, the number of samples directly affects the algorithm's performance and may even cause divergence. In this work, we propose an adaptive technique to mitigate the sampling noise by adopting a switching control law in the design of the feedback-based algorithm. The proposed technique can lead to better performance and convergence properties. We show the robustness of our technique against sampling noise through an application for the maximum clique problem.
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    Article
    Citation - WoS: 1
    Citation - Scopus: 1
    Certification of almost global phase synchronization of all-to-all coupled phase oscillators
    (Pergamon-Elsevier Science Ltd, 2023) Kudeyt, Mahmut; Kivilcim, Aysegul; Koksal-Ersoz, Elif; Ilhan, Ferruh; Karabacak, Ozkan
    Coupled oscillators may exhibit almost global phase synchronization, namely their phases tend to asymp-totically overlap for almost all initial conditions. We consider certification of this property using Rantzer's dual Lyapunov approach with sum of squares (SOS) programming. To this aim, we use a stereographic transformation from a hypertorus to an Euclidean space. For the case of all-to-all coupling, this transformation converts the problem of certifying stability into the problem of certifying divergence of almost all solutions to infinity. We show that the latter can be solved using a polynomial Lyapunov density, which can be constructed via SOS programming. This leads to the certification of almost global phase synchronization of all-to-all coupled phase oscillators. We apply our method to an example of coupled phase oscillators and to an example of coupled van der Pol oscillators, and show that it can support the existing tools of local stability analysis by ensuring almost global phase synchronization.
  • Thumbnail Image
    Article
    Feedback-Based Quantum Algorithm for Excited States Calculation
    (Institute of Electrical and Electronics Engineers Inc., 2026) Abdul Rahman, S.A.; Karabacak, Ö.; Wisniewsk, R.
    Recently, feedback-based quantum algorithms have been introduced to calculate the ground states of Hamiltonians, inspired by quantum Lyapunov control theory. This paper aims to generalize these algorithms to the problem of calculating an eigenstate of a given Hamiltonian, assuming that the lower energy eigenstates are known. To this aim, we propose a new design methodology that combines the layer wise construction of the quantum circuit in feedback-based quantum algorithms with a new feedback law based on a new Lyapunov function to assign the quantum circuit parameters. We present two approaches for evaluating the circuit parameters: one based on the expectation and overlap estimation of the terms in the feedback law and another based on the gradient of the Lyapunov function. We demonstrate the algorithm through an illustrative example and through an application in quantum chemistry. To assess its performance, we conduct numerical simulations and execution on IBM's superconducting quantum computer. © 2020 IEEE.
  • Thumbnail Image
    Conference Object
    Citation - WoS: 2
    Citation - Scopus: 3
    Feedback-Based Quantum Algorithm for Constrained Optimization Problems
    (Springer International Publishing AG, 2025) Rahman, Salahuddin Abdul; Karabacak, Ozkan; Wisniewski, Rafal
    The feedback-based algorithm for quantum optimization (FALQON) has recently been proposed to find ground states of Hamiltonians and solve quadratic unconstrained binary optimization problems. This paper efficiently generalizes FALQON to tackle quadratic constrained binary optimization (QCBO) problems. For this purpose, we introduce a new operator that encodes the problem's solution as its ground state. Using control theory, we design a quantum control system such that the state converges to the ground state of this operator. When applied to the QCBO problem, we show that our proposed algorithm saves computational resources by reducing the depth of the quantum circuit and can perform better than FALQON. The effectiveness of our proposed algorithm is further illustrated through numerical simulations.