Electrical & Electronics Engineering
Permanent URI for this collectionhttps://hdl.handle.net/10679/44
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Browsing by Institution Author "DURAK, Kadir"
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ArticlePublication Metadata only Attack to quantum cryptosystems through RF fingerprints from photon detectors(IEEE, 2022-03) Durak, Kadir; Jam, Naser Chamani; Karamzadeh, S.; Electrical & Electronics Engineering; DURAK, Kadir; Jam, Naser ChamaniThe well-known RF penetration method is implemented on the quantum cryptosystems. In this study, RF radiations from the single photon detectors in a quantum key distribution system are intercepted. It was found that the data contents of a quantum transmission system can be detected from the vicinity of the receiving parties by exploiting the radiations of avalanche effect of single photon detectors. We showed that any Geiger-mode avalanche photodetector acts like a downconverter that converts the optical-wavelength photons to radio-wavelength photons. In our experiment, the fingerprints of the avalanche radiations from commercial single photon detectors were fed to a trained deep learning neural network, and the bit content of quantum transmission was cloned with >99% accuracy up to a distance of 2 meters from the detectors. We also speculate on the enhancement of the key cloning accuracy and range of the eavesdropping.ArticlePublication Metadata only Cryptographic security concerns on timestamp sharing via a public channel in quantum-key-distribution systems(American Physical Society, 2022-07) Pahalı, Melis; Durak, Kadir; Tefek, U.; Electrical & Electronics Engineering; DURAK, Kadir; Pahalı, MelisQuantum-key-distribution protocols are known to be vulnerable against a side channel attack that exploits the time difference in detectors' responses used to obtain key bits. The recommended solution against this timing side channel attack is to use a large time bin width instead of high-resolution timing information. A common notion is that using a large bin width reduces the resolution of detectors' responses, hence supposedly minimizes the information leakage to an eavesdropper. We challenge this conventional wisdom and demonstrate that increasing the bin width does not monotonically reduce the mutual information between the key bits and the eavesdropper's observation of detectors' responses. Instead of randomly increasing the bin width, it should be carefully chosen because the mutual information fluctuates with respect to the bin width. We also examine the effect of full width half maximums (FWHMs) of the detectors' responses on the mutual information and show that decreasing the FWHM increases the mutual information. Lastly, the start time of binning is also shown to be important in the binning process and the mutual information fluctuates periodically with respect to it.ArticlePublication Metadata only Development of an aerial interface for extraction of the electrodynamic fingerprints of the single-photon detectors(Wiley, 2021-12) Karamzadeh, S.; Durak, Kadir; Jam, Naser Chamani; Rafiei, V.; Awad, B.; Electrical & Electronics Engineering; DURAK, Kadir; Jam, Naser ChamaniIn this study, a novel structure of semi array of antipodal Vivaldi antenna is designed to extract the RF radiations from the single-photon detectors in a quantum key distribution system. The proposed antenna covers a frequency range from 2 to 12 GHz with an average gain of 12.5 dBi which has improved by a lens structure. In the first step, the design proceeding of the antenna has been discussed, and then, some of the unique futures of the proposed antenna which promoted it to use in quantum attack systems, such as linear momentum, a good Envelope Correlation Coefficient, and Gaussian pulse response, are discussed.Conference ObjectPublication Metadata only Down-conversion emission profile characterisation via camera(Optica Publishing Group, 2020-12-14) Kuniyil, Hashir Puthiyapurayil; Durak, Kadir; Electrical & Electronics Engineering; DURAK, Kadir; Kuniyil, Hashir PuthiyapurayilWe present a method to improve the brightness and collection efficiency of the spontaneous parametric down-conversion source by monitoring the mode shape using camera and correcting it with collection optics.Conference ObjectPublication Metadata only Effect of phase and spatial distinguishability of photon pairs on the entanglement fidelity(SPIE, 2021) Kuniyil, Hashir Puthiyapurayil; Durak, Kadir; Electrical & Electronics Engineering; DURAK, Kadir; Kuniyil, Hashir PuthiyapurayilPolarization entanglement based cryptography uses the photon pairs generated in a spontaneous parametric down-conversion process and guarantees the security through the violation of Bell's inequality. Certain experimental parameters affects the entanglement fidelity and leads to a possible information leakage. The optical path difference of photons born at different crystals contributes to reduced fidelity, due to the extra birefringence of the nonlinear crystal. Although previous studies suggested methods to erase the distinguishability of photons by introducing compensation crystals, the phase difference, which is due to the lateral ray distribution is not studied. We used two commercially available collection optics; an aspheric and an achromatic lens. With these collection optics, the effect of collection optics on the entanglement fidelity is studied. We developed a simulation of such a system and found that aspheric collection optics is more suitable to achieve high fidelity.ArticlePublication Metadata only Effect of photon statistics on vacuum fluctuations based QRNG(IOP Publishing, 2021-06) Dandaşi, Abdulrahman; Özel, Helin; Hasekioglu, O.; Durak, Kadir; Electrical & Electronics Engineering; DURAK, Kadir; Dandaşi, Abdulrahman; Özel, HelinThe speed of quantum random number generators (QRNGs) is a major concern for practical applications. In this work, we introduce scattering as a method to enhance the randomness characteristics of the entropy source. This method allows optical bit extraction with a faster sampling rate without compromising the randomness quality compared to the coherent source based balanced homodyne detection. Scattering is a probabilistic phenomenon which increases the chaotic behaviour of coherent sources. It broadens the distribution of photon statistics and makes it super-Poissonian. We show that a signal with super-Poissonian distribution has better randomness compared to a Poissonian one, indicated by their autocorrelation characteristics and the randomness test results. The use of scattering mechanisms as an entropy source eases the miniaturization of QRNGs, it also makes them compatible and adaptable to existing technologies.ArticlePublication Metadata only Efficient coupling of down-converted photon pairs into single mode fiber(Elsevier, 2021-08-15) Kuniyil, Hashir Puthiyapurayil; Durak, Kadir; Electrical & Electronics Engineering; DURAK, Kadir; Kuniyil, Hashir PuthiyapurayilWe present the analysis of the down-conversion emission profile from a critically phase-matched type-I nonlinear crystal. The emission profile of the down-conversion modes shows asymmetry in cylindrical coordinate system due to the birefringent effects of the nonlinear crystal, i.e. pump walk-off. This effect leads to reduced collection of the pairs from the source to the single mode fiber, which limits the brightness as a function of the crystal length. We propose a method to improve the symmetry of the down-conversion modes by inserting a lens off-centered with respect to the optical axis. Our theoretical and experimental results show that the asymmetry of the system increases with the crystal length by L0.5, and the brightness is proportional to crystal length by L0.72 and L0.91 for uncorrected and corrected down conversion mode profiles, respectively. The proposed method allows more efficient use of photon pair sources in terms of brightness which is to be used in quantum optics applications.ArticlePublication Open Access Entanglement demonstration on board a nano-satellite(The Optical Society, 2020-07-20) Villar, A.; Lohrmann, A.; Bai, X.; Vergoossen, T.; Bedington, R.; Perumangatt, C.; Lim, H. Y.; Islam, T.; Reezwana, A.; Tang, Z.; Chandrasekara, R.; Sachidananda, S.; Durak, Kadir; Wildfeuer, C. F.; Griffin, D.; Oi, D. K. L.; Ling, A.; Electrical & Electronics Engineering; DURAK, KadirGlobal quantum networks for secure communication can be realized using large fleets of satellites distributing entangled photon pairs between ground-based nodes. Because the cost of a satellite depends on its size, the smallest satellites will be most cost-effective. This Letter describes a miniaturized, polarization entangled, photon-pair source operating on board a nano-satellite. The source violates Bell's inequality with a Clauser-Horne-Shimony-Holt parameter of 2.60 +/- 0.06. This source can be combined with optical link technologies to enable future quantum communication nano-satellite missions.Conference ObjectPublication Metadata only Entanglement demonstration on board a nano-satellite(Optica Publishing Group, 2020) Villar, A.; Lohrmann, A.; Bai, X.; Vergoosen, T.; Bedington, R.; Perumangatt, C.; Lim, H. Y.; Islam, T.; Reezwana, A.; Tang, Z.; Chandrasekara, R.; Sachidananda, S.; Durak, Kadir; Wildfeuer, C. F.; Griffin, D.; Oi, D. K. L.; Ling, A.; Electrical & Electronics Engineering; DURAK, KadirPolarization entangled photon-pairs are generated and detected onboard a 3U CubeSat in low-Earth orbit that violate Bell’s inequality with a CHSH parameter of 2.60 ± 0.06. These results pave the way for space-based quantum networks.ArticlePublication Metadata only Noise-tolerant object detection and ranging using quantum correlations(IOP Publishing, 2022-10) Kuniyil, Hashir Puthiyapurayil; Özel, Helin; Yılmaz, H.; Durak, Kadir; Electrical & Electronics Engineering; DURAK, Kadir; Kuniyil, Hashir Puthiyapurayil; Özel, HelinImaging, detection and ranging of objects in the presence of significant background noise is a fundamental challenge in optical sensing. Overcoming the limitations imposed in conventional methods, quantum light sources show higher resistance against noise in a time-correlation-based quantum illumination. Here, we introduce the advantage of using not only time correlations but also polarization correlations in photon pairs in the detection of an object that is embedded in a noisy background. In this direction, a time- and polarization-correlated photon pair source using the spontaneous parametric down-conversion process is exploited. We found that the joint measurement of correlated pairs allows distinguishing the signal from the noise photons and that leads to an improved signal-to-noise ratio. Our comparative study revealed that using polarization correlations in addition to time correlations provides improved noise rejection. Furthermore, we show that polarization correlation allows undoing the detector limitation where high background often leads to detector saturation.Conference ObjectPublication Metadata only Object ranging and sensing by temporal cross-correlation measurement(SPIE, 2020) Kuniyil, Hashir Puthiyapurayil; Jam, Naser Chamani; Durak, Kadir; Electrical & Electronics Engineering; Kimata, M.; Shaw, J. A.; Valenta, C. R.; DURAK, Kadir; Kunıyıl, Hashır Puthıyapurayıl; Jam, Naser ChamanıWe present a novel method to measure the range of an object in a lab setting. This is realised by utilizing the phase insensitive cross-correlation analysis of the probe and reference photons generated in a spontaneous parametric down-conversion process. In our technique, the comparative measurement of time-correlated photons after one is transmitted to the target direction and the copy of it retained at the lab allows to single out the signal from the noise lead to sense, range and imaging the sample.Conference ObjectPublication Metadata only Object tracking and identification by quantum radar(SPIE, 2019) Durak, Kadir; Jam, Naser Chamani; Dindar, Çağrı; Electrical & Electronics Engineering; Rarity, J. G.; Kimata, M.; Shaw, J. A.; Valenta, C. R.; DURAK, Kadir; Jam, Naser Chamanı; Dindar, ÇağrıQuantum Radar is a promising technology that could have a strong impact on the civilian and military realms. In this study we introduce a new concept design for implementing a Quantum Radar, based on the time and polarization correlations of the entangled photons for detection and identification and tracking of high-speed targets. The design is focused on extracting high resolution details of the target with precision timing of entangled photons that provides important operational capabilities like distinguishing a target from a decoy. The quantum entanglement properties guarantee the legitimacy of the photons captured by the search telescope. Time correlations of the photon detection events can be extracted via cross-correlation operation between two sets of photon detection time-tags for the entangled photons. The fact that the wavelengths of the entangled photons can be tuned also makes the Quantum Radar concept an enticing candidate for tracking stealth objects. We present the proof-of-principle test results of the Quantum Radar and discuss the technical challenges and limitations of the design.ArticlePublication Open Access Optimization of collection optics for maximum fidelity in entangled photon sources(TÜBİTAK, 2020) Durak, Kadir; Electrical & Electronics Engineering; DURAK, KadirIn this report, decoherence sources for entangled photons created by spontaneous parametric down-conversion phenomenon are studied. The phase and spatial distinguishability of photon pairs from orthogonal crystals reduce the maximum achievable entanglement fidelity. Carefully chosen compensation crystals are used to erase the phase and spatial traces of down-conversion origins. Emission angle of photon pairs also leads to optical path difference and results in phase distinguishability. A realistic scenario is numerically modelled, where the photon pairs with nonzero emission angle gather a phase difference. These pairs can still be collected and manipulated for practical use but the collection optics adds upon the phase difference. Two commercially available optics for collection; aspheric and achromatic lenses are compared. The numerical simulation results are compared with the experimental results to validate the built model for predicting the maximum achievable entanglement fidelity. The results indicate that the fidelity can be accurately estimated with the presented model by inserting the experimental parameters to it. The study is expected to be very useful for preparation and optimization of entangled photon pair sources in critical phase-matching configuration.Conference ObjectPublication Metadata only Photon statistics effects on a QRNG of vacuum fluctuations(Optica Publishing Group, 2020-09-14) Dandaşi, Abdulrahman; Özel, Helin; Durak, Kadir; Electrical & Electronics Engineering; DURAK, Kadir; Dandaşi, Abdulrahman; Özel, HelinOptical scattering enhances randomness characteristics, increases the chaotic behavior of coherent sources, broadens the distribution of photon statistics and makes it super-Poissonian which allows faster sampling compared to Poissonian.Conference ObjectPublication Metadata only Pseudothermal light based quantum random number generator(IEEE, 2020-10-22) Özel, H.; Dandaşi, Abdulrahman; Durak, Kadir; Electrical & Electronics Engineering; DURAK, Kadir; Dandaşi, AbdulrahmanThe importance of quantum random number generators (QRNGs) is increasing day by day. An important aspect of any QRNG is the speed of the system. This paper introduces the theory behind a pseudothermal light based QRNG. This pseudothermal effect is provided by using an optical scatterer in the setup. Pseudothermal light is used as the local oscillator of the system instead of a conventional coherent or thermal light source where the pseudothermal light combines the advantages of both sources. This technique converts the Poissonian distribution of light to super-Poissonian to have better randomness characteristics and allow a faster bit generation rate.Conference ObjectPublication Metadata only PYNQ-based rapid FPGA implementation of quantum key distribution(IEEE, 2021) Bilgin, Yiğit; Tesfay, Shewıt Weldu; İpek, Seçkin; Uğurdağ, Hasan Fatih; Durak, Kadir; Gören, S.; Electrical & Electronics Engineering; UĞURDAĞ, Hasan Fatih; DURAK, Kadir; Bilgin, YiğitIn this paper, we present a real-time Quantum Key Distribution (QKD) implementation on Field Programmable Gate Arrays (FPGAs) for secure communication. We propose a novel methodology with a Python-based programming interface for rapid development on FPGA. Our methodology revolves three phases of development. In the first phase, a reference model of an entangled photon source and the proposed QKD system are developed in Python. Next, the reference model is passed through a thorough verification phase. In the second phase, the reference model is implemented on the Processing System (PS) part of the FPGA. Finally in the third phase, the computationally intensive part of the QKD architecture is off-loaded on to the Programmable Logic (PL) part of the FPGA for acceleration. We employ PYNQ framework in our QKD development and successfully combine the convenience of Python productivity with FPGA based acceleration.ArticlePublication Open Access Quantum signatures in a quadratic optomechanical heat engine with an atom in a tapered trap(Optica Publishing Group, 2022-12) Izadyari, M.; Öncü, Mehmet; Durak, Kadir; Müstecaplioğlu, Ö. E.; Electrical & Electronics Engineering; DURAK, Kadir; Öncü, MehmetWe investigate how quantum signatures can emerge in a single atom heat engine consisting of an atom confined in a tapered trap and subjected to hot and cold thermal reservoirs. A similar system was realized experimentally in Science 352, 325 (2016). We model such a system using a quadratic optomechanical model and identify an effective Otto cycle in the system’s dynamics. We compare the engine’s performance in quantum and classical regimes by evaluating the power dissipated. We find that lowering the temperature is insufficient to make the single atom engine in Science 352, 325 (2016) a genuine quantum-enhanced heat engine. We show that it is necessary to make the trap more asymmetric and confined to ensure that quantum correlations cause an enhancement in the power output.Conference ObjectPublication Metadata only Single photon detection with silicon-based avalanche photodiode(SPIE, 2023) Yerli, Burcu; Eraydın, Can; Cinkaya, H.; Durak, Kadir; Electrical & Electronics Engineering; DURAK, Kadir; Yerli, Burcu; Eraydın, CanThanks to the significant advances in quantum technologies, the use of single photon detectors (SPDs) is becoming increasingly common. As a result of the excellent photodetection performance of these detectors, they have been utilized in a wide range of fields such as quantum cryptography, astronomy, spectroscopy, and medical applications. There is no doubt that improvements in the performance of these detectors will open new paths to their multidisciplinary applications. Over the years, several different types of SPDs have been developed, such as photomultiplier tubes based on vacuum tubes, avalanche photodiodes (APDs) based on semiconductors, or nanowires based on superconducting technology. Any of these technologies, which are also commercially offered by many companies, has been used according to their advantages and disadvantages for intended applications by making a trade-off. At that point, SPDs based on Silicon APD technology have many advantages including low voltage operation, high reliability, simple electronic requirements, and high detection efficiency. In this study, the TO-8 SAP500 series Silicon APD provided by Laser Component was preferred, and the driving circuit was designed for visible-range sensing applications. The quenching and thermoelectric cooling circuit designs were presented, and the performance of the detector was analyzed according to some important parameters. Our motivation is to investigate the CubeSat compatibility of the detector for space applications.ArticlePublication Metadata only Tracking capacitance of liquid crystal devices to improve polarization rotation accuracy(Optical Society of America, 2017-08-21) Chandrasekara, R.; Durak, Kadir; Ling, A.; Electrical & Electronics Engineering; DURAK, KadirWe report a capacitance tracking method for achieving arbitrary polarization rotation from nematic liquid crystals. By locking to the unique capacitance associated with the molecular orientation, any polarization rotation can be achieved with improved accuracy over a wide temperature range. A modified relaxation oscillator circuit that can simultaneously determine the capacitance and drive the rotator is presented.