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Permanent URI for this collectionhttps://hdl.handle.net/20.500.14288/3
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Publication Metadata only Contrast improvement through a Generative Adversarial Network (GAN) by utilizing a dataset obtained from a line-scanning confocal microscope(SPIE, 2024) Department of Physics; Kiraz, Alper; Morova, Berna; Bavili, Nima; Ketabchi, Amir Mohammad; Department of Physics; Koç University Research Center for Translational Medicine (KUTTAM) / Koç Üniversitesi Translasyonel Tıp Araştırma Merkezi (KUTTAM); College of Sciences; Graduate School of Sciences and EngineeringConfocal microscopy offers enhanced image contrast and signal-to-noise ratio compared to wide-field illumination microscopy, achieved by effectively eliminating out-of-focus background noise. In our study, we initially showcase the functionality of a line-scanning confocal microscope aligned through the utilization of a Digital Light Projector (DLP) and a rolling shutter CMOS camera. In this technique, a sequence of illumination lines is projected onto a sample using a DLP and focusing objective (50X, NA=0.55). The reflected light is imaged with the camera. Line-scanning confocal imaging is accomplished by synchronizing the illumination lines with the rolling shutter of the sensor, leading to a substantial enhancement of approximately 50% in image contrast. Subsequently, this setup is employed to create a dataset comprising 500 pairs of images of paper tissue. This dataset is employed for training a Generative Adversarial Network (cGAN). Roughly 45% contrast improvement was measured in the test images for the trained network, in comparison to the ground-truth images.Publication Metadata only Temporal evolution of entropy and chaos in low amplitude seismic wave prior to an earthquake(Pergamon-Elsevier Science Ltd, 2023) Akilli, Mahmut; Ak, Mine; Department of Physics; Yılmaz, Nazmi; Department of Physics; College of SciencesThis study investigates the temporal changes of entropy and chaos in low-amplitude continuous seismic wave data prior to two moderate-level earthquakes. Specifically, we examine seismic signals before and during the Istanbul-Turkey earthquake of September 26, 2019 (M = 5.7), and the Duzce-Turkey earthquake of November 17, 2021 (M = 5.2), which occurred near the Marmara Sea region on the north-Anatolian fault line. We aim to identify changes in complexity and chaotic characteristics in the pre-earthquake seismic waves and explore the possibility of earthquake forecasting minutes before an earthquake. To accomplish this, we utilize windowed scalogram entropy and sample entropy methods and compared the results with Lyapunov exponents and windowed scale index. Our findings indicate that measuring the temporal change of entropy using windowed scalogram entropy is sensitive to the change in complexity due to the frequency shifts during the weak ground motion approaching an earthquake.On the other hand, Lyapunov exponents and sample entropy appear more effective in their response to the change in complexity and chaotic characteristics due to the change in the signal amplitude. Additionally, the windowed scale index can detect temporal fluctuations in the aperiodicity of the signal. Overall, our results suggest that all four methods can be valuable in characterizing complexity and chaos in short-time pre -earthquake seismic signals, differentiating earthquakes, and contributing to the development of earthquake forecasting techniques.Publication Metadata only Identifying connectivity for two sympatric carnivores in human-dominated landscapes in central Iran (vol 17, e0269179, 2022)(Public Library Science, 2023) Rezaei, Sahar; Mohammadi, Alireza; Bencini, Roberta; Rooney, Thomas; Department of Physics; Department of Physics; ; College of Sciences;The affiliation for the last author is incorrect. The correct affiliation for Morteza Naderi is Arak University. An additional affiliation is missing for the last author. Morteza Naderi is also affiliated with the Department of Molecular Biology and Genetics, Faculty of Sciences, Koc University, Istanbul, Turkey. © 2023 Rezaei et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Publication Metadata only Low-temperature quantum thermometry boosted by coherence generation(American Physical Society, 2023) ; Department of Physics; Ullah, Asghar; Naseem, Muhammad Tahir; Müstecaplıoğlu, Özgür Esat; Department of Physics; ; Graduate School of Sciences and Engineering; College of Sciences;The precise measurement of low temperatures is significant for both the fundamental understanding of physical processes and technological applications. In this work, we present a method for low-temperature measurement that improves thermal range and sensitivity by generating quantum coherence in a thermometer probe. Typically, in temperature measurements, the probes thermalize with the sample being measured. However, we use a two-level quantum system, or qubit, as our probe and prevent direct probe access to the sample by introducing a set of ancilla qubits as an interface. We describe the open system dynamics of the probe using a global master equation and demonstrate that while the ancilla-probe system thermalizes with the sample, the probe per se evolves into a nonthermal steady state due to nonlocal dissipation channels. The populations and coherences of this steady state depend on the sample temperature, allowing for precise and wide-range low-temperature estimation. We characterize the thermometric performance of the method using quantum Fisher information and show that the quantum Fisher information can exhibit multiple and higher peaks at different low temperatures with increasing quantum coherence and the number of ancilla qubits. Our analysis reveals that the proposed approach, using a nonthermal qubit thermometer probe with temperature-dependent quantum coherence generated by a multiple qubit interface between a thermal sample and the probe qubit, can enhance the sensitivity of temperature estimation and broaden the measurable low-temperature range. © 2023 authors. Published by the American Physical Society. Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.Publication Metadata only Geometrical optimization of spin clusters for the preservation of quantum coherence(American Physical Society, 2024) ; Department of Physics; Gassab, Lea; Pusuluk, Orhan; Müstecaplıoğlu, Özgür Esat; Department of Physics; ; Graduate School of Sciences and Engineering; College of Sciences;We investigate the influence of geometry on the preservation of quantum coherence in spin clusters subjected a thermal environment. Assuming weak interspin coupling, we explore the various buffer network configura yons that can be embedded in a plane. Our findings reveal that the connectivity of the buffer network is crucial indetermining the preservation duration of quantum coherence in an individual central spin. Specifically, we observe that the maximal planar graph yields the longest preservation time for a given number of buffer spins. Interestingly, our results demonstrate that the preservation time does not consistently increase with an increasing #umber of buffer spins. Employing a quantum master equation in our simulations, we further demonstrate that a Cetrahedral geometry comprising a four-spin buffer network provides optimal protection against environmental Tects.Publication Metadata only Conditions on detecting tripartite entangled state in psychophysical experiments(SPRINGER HEIDELBERG, 2024) Department of Physics; Gassab, Lea; Pedram, Ali; Müstecaplıoğlu, Özgür Esat; Department of Physics; Graduate School of Sciences and Engineering; College of SciencesThis paper explores the sensitivity of the human visual system to quantum entangled light. We examine the possibility of human subjects perceiving multipartite entangled state through psychophysical experiments. Our focus begins with a bipartite entangled state to make a comparative study with the literature by taking into account additive noise for false positive on bipartite entanglement perception by humans. After that, we limit our similar investigation to a tripartite entangled state for simplicity in higher dimensions. To model the photodetection by humans, we employ the probability of seeing determined for coherently amplified photons in Fock number states, including an additive noise. Our results indicate that detecting bipartite and tripartite entanglement with the human eye is possible for a certain range of additive noise levels and visual thresholds. Finally, we discuss several alternative amplification methods.Publication Metadata only What is quantum in probabilistic explanations of the sure-thing principle violation?(Elsevier Ireland Ltd, 2024) Department of Physics; Mahalli, Nematollah Farhadi; Pusuluk, Orhan; Department of Physics; College of SciencesThe Prisoner's Dilemma game (PDG) is one of the simple test-beds for the probabilistic nature of the human decision-making process. Behavioral experiments have been conducted on this game for decades and show a violation of the so-called sure-thing principle, a key principle in the rational theory of decision. Quantum probabilistic models can explain this violation as a second-order interference effect, which cannot be accounted for by classical probability theory. Here, we adopt the framework of generalized probabilistic theories and approach this explanation from the viewpoint of quantum information theory to identify the source of the interference. In particular, we reformulate one of the existing quantum probabilistic models using density matrix formalism and consider different amounts of classical and quantum uncertainties for one player's prediction about another player's action in PDG. This enables us to demonstrate that what makes possible the explanation of the violation is the presence of quantum coherence in the player's initial prediction and its conversion to probabilities during the dynamics. Moreover, we discuss the role of other quantum information-theoretical quantities, such as quantum entanglement, in the decision-making process. Finally, we propose a three-choice extension of the PDG to compare the predictive powers of quantum probability theory and a more general probabilistic theory that includes it as a particular case and exhibits third-order interference. © 2024 Elsevier B.V.Publication Metadata only Optical modulation with silicon microspheres(IEEE-Inst Electrical Electronics Engineers Inc, 2009) Gürlü, Oğuzhan; N/A; Department of Physics; Yüce, Emre; Serpengüzel, Ali; Master Student; Faculty Member; Department of Physics; Graduate School of Sciences and Engineering; College of Sciences; 245435; 27855In this letter, a silicon microsphere coupled to a silica optical fiber half coupler has been characterized for electrooptical modulation in the L-band at 1.55 mu m. Electrooptical modulation of the transmitted and the 90 degrees elastic scattered signals for both the TE and the TM polarizations of the microsphere resonances has been observed.Publication Metadata only Resonant channel-dropping filter with integrated detector system based on optical fiber coupler and microsphere(IOP Publications, 2004) İşci, Şenol; Yılmaz, Yiğit; Department of Physics; Serpengüzel, Ali; Kurt, Adnan; Bilici, Temel; Faculty Member; Teaching Faculty; N/A; Department of Physics; College of Sciences; N/A; 27855; 194455; N/APublication Metadata only Concentration dependence of the infrared luminescence efficiencies in TEO-CDCL2 : TM3+ glass(Optica Publishing Group, 2003) Özalp, M. Reha; Özen, Gönül; Department of Physics; Department of Physics; Sennaroğlu, Alphan; Kurt, Adnan; Faculty Member; Teaching Faculty; Department of Physics; College of Sciences; College of Sciences; 23851; 194455Using exper imental methods, the characteristics of the 1450-nm and 1800-nm luminescence bands of Tm3+ doped TeO2-CdCl2 glasses were studied as a function of the Tm3+ doping level.