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نتیجه جستجو - Polar

تعداد مقالات یافته شده: 110
ردیف عنوان نوع
1 Design of an Integrated Bell-State Analyzer on a Thin-Film Lithium Niobate Platform
طراحی یک آنالایزر حالت زنگ یکپارچه بر روی بستر نازک لیتیوم نیوبات-2022
Trapped ions are excellent candidates for quantum computing and quantum networks because of their long coherence times, ability to generate entangled photons as well as high fidelity single- and two-qubit gates. To scale up trapped ion quantum computing, we need a Bell-state analyzer on a reconfigurable platform that can herald high fidelity entanglement between ions. In this work, we design a photonic Bell-state analyzer on a reconfigurable thin-film lithium niobate platform for polarization-encoded qubits.We optimize the device to achieve high fidelity entanglement between two trapped ions and find >99% fidelity. Apart from that, the directional coupler used in our design can achieve any polarization-independent power splitting ratio which can have a rich variety of applications in the integrated photonic technology. The proposed device can scale up trapped ion quantum computing as well as other optically active spin qubits, such as color centers in diamond, quantum dots, and rare-earth ions.
Index Terms: Bell-state analyzer | thin-film lithium niobate | scalable quantum computing | trapped ions | entanglement | polarization qubits | polarization-independent directional coupler.
مقاله انگلیسی
2 Tracking the northern seasonal cap retreat of mars using computer vision
ردیابی عقب نشینی کلاهک فصلی شمالی مریخ با استفاده از بینایی کامپیوتر-2022
Using polar stereographic images from the Mars Color Imager (MARCI), we use Python to autonomously track the Northern Polar Seasonal Cap (NPSC) recession from Mars Years (MY) 29 to MY 35 between Ls = 10° and Ls = 70°. We outline the cap and find an ellipse of best fit. We then compare our results to previously published recession rates, that were manually tracked, and find them to be consistent. Our process benefits from being automated, which increases the speed of tracking and allows us to monitor the recession with higher Ls fidelity than past studies. We find that most MYs have a local minimum recession rate at Ls = ~32° and a local maximum at Ls = ~51°. We also find that MY 30 experiences a rapid latitude increasing event that involves ~1° Ls of a rapid increase and ~5° Ls of slower recession, which then increases above the interannual average rate. We interpret this to be the result of a major sublimation driven by off-polar winds. We also discover divergent effects in the recession and size of the NPSC following the MY 28 and MY 35 global dust storms. MY 29’s cap is significantly smaller and retreats slower than the multi-year average, whereas MY 35’s cap is slighter larger and retreats very close to the average. We hypothesize that the diverging behavior of the caps in post-storm years can be a result of the differences in the date of onset and the duration of the storms.
مقاله انگلیسی
3 Generation of Truly Random Numbers on a Quantum Annealer
تولید اعداد واقعا تصادفی در یک آنیلر کوانتومی-2022
This study investigates how qubits of modern quantum annealers (QA) such as D-Wave can be applied for generating truly random numbers. We show how a QA can be initialised and how the annealing schedule can be set so that after the annealing, thousands of truly random binary numbers are measured in parallel. Those can then be converted to uniformly distributed natural or real numbers in desired ranges, either biased or unbiased. We discuss the observed qubits’ properties and their influence on the random number generation and consider various physical factors that influence the performance of our generator, i.e., digital-to-analogue quantisation errors, flux errors, temperature errors and spin bath polarisation. The numbers generated by the proposed algorithm successfully pass various tests on randomness from the NIST test suite. Our source code and large sets of truly random numbers will be made publicly available on our project web page.
INDEX TERMS: Random numbers | true randomness test | superconducting flux qubits | quantum annealing | QUBO
مقاله انگلیسی
4 Natural Embedding of the Stokes Parameters of Polarimetric Synthetic Aperture Radar Images in a Gate-Based Quantum Computer
جاسازی طبیعی پارامترهای استوکس تصاویر رادار دیافراگم مصنوعی قطبی در یک کامپیوتر کوانتومی مبتنی بر گیت-2022
Quantum algorithms are designed to process quantum data (quantum bits) in a gate-based quantum computer. They are proven rigorously that they reveal quantum advantages over conventional algorithms when their inputs are certain quantum data or some classical data mapped to quantum data. However, in a practical domain, data are classical in nature, and they are very big in dimension, size, and so on. Hence, there is a challenge to map (embed) classical data to quantum data, and even no quantum advantages of quantum algorithms are demonstrated over conventional ones when one processes the mapped classical data in a gate-based quantum computer. For the practical domain of earth observation (EO), due to the different sensors on remotesensing platforms, we can map directly some types of EO data to quantum data. In particular, we have polarimetric synthetic aperture radar (PolSAR) images characterized by polarized beams. A polarized state of the polarized beam and a quantum bit are the Doppelganger of a physical state. We map them to each other, and we name this direct mapping a natural embedding, otherwise an artificial embedding. Furthermore, we process our naturally embedded data in a gate-based quantum computer by using a quantum algorithm regardless of its quantum advantages over conventional techniques; namely, we use the QML network as a quantum algorithm to prove that we naturally embedded our data in input qubits of a gate-based quantum computer. Therefore, we employed and directly processed PolSAR images in a QML network. Furthermore, we designed and provided a QML network with an additional layer of a neural network, namely, a hybrid quantum-classical network, and demonstrate how to program (via optimization and backpropagation) this hybrid quantum-classical network when employing and processing PolSAR images. In this work, we used a gate-based quantum computer offered by an IBM Quantum and a classical simulator for a gate-based quantum computer. Our contribution is that we provided very specific EO data with a natural embedding feature, the Doppelganger of quantum bits, and processed them in a hybrid quantum-classical network. More importantly, in the future, these PolSAR data can be processed by future quantum algorithms and future quantum computing platforms to obtain (or demonstrate) some quantum advantages over conventional techniques for EO problems.
Index Terms: Natural embedding | parameterized quantum circuit | polarimetric synthetic aperture radar (PolSAR) | quantum machine learning (QML).
مقاله انگلیسی
5 Polarization-Based Quantum Key Distribution Encoder and Decoder on Silicon Photonics
رمزگذار و رمزگشای توزیع کلید کوانتومی مبتنی بر پلاریزاسیون در فوتونیک سیلیکون-2022
Private and secure communication is an indispensable part of the government and individual activities. With the everevolving large-scale of quantum computing, traditional public-key cryptography is severely threatened since its security only relies on the computational complexity of certain mathematical functions. Quantum key distribution (QKD), ascribed to its security based on the inviolability of physics laws, provides an absolutely information-secure solution for the future extensive communication encrypting. Herein this Letter, we proposed a simplified and reconfigurable silicon photonics encoder using a pass-block architecture and experimentally demonstrated its performance with a specialized silicon photonics decoder for high-speed quantum key distribution in polarization-based decoy-state BB84 protocol. We achieved an estimated asymptotic secret key rate of 868 kbps with measured quantum bit error rate (QBER) of 0.90% (Z base) and 1.34% (X base) over 20 km emulated fiber link. This work further advances the process of applying QKD using silicon photonics devices into the future secure telecommunication network.
Index Terms: Quantum key distribution (QKD) | silicon photonics.
مقاله انگلیسی
6 Polar Codes for Quantum Reading
کدهای قطبی برای خواندن کوانتومی-2022
Quantum readout provides a general framework for formulating statistical discrimination of quantum channels. Several paths have been taken for such this problem. However, there is much to be done in the avenue of optimizing channel discrimination using classical codes. At least two open questions can be pointed out: how to construct low complexity encoding schemes that are interesting for channel discrimination and, more importantly, how to develop capacity-achieving protocols. This paper aims at presenting a solution to these questions using polar codes. Firstly, we characterize the information rate and reliability parameter of the channels under polar encoding. We also show that the error probability of the scheme proposed decays exponentially with the square root of the code length. Secondly, an analysis of the optimal quantum states to be used as probes is given.
keywords: Quantum reading | polar codes | capacity achieving protocols.
مقاله انگلیسی
7 Cost-Effective ML-Powered Polarization-Encoded Quantum Key Distribution
توزیع کلید کوانتومی کدگذاری شده با قطبش ML مقرون به صرفه-2022
Secure communications have become a requirement for virtually all kind of applications. Currently, two distant parties can generate shared random secret keys by using public key cryptography. However, quantum computing represents one of the greatest threats for the finite complexity of the mathematics behind public key cryptography. In contrast, Quantum Key Distribution (QKD) relies on properties of quantum mechanics, which enables eavesdropping detection and guarantees the security of the key. Among QKD systems, polarization encoded QKD has been successfully tested in laboratory experiments and recently demonstrated in closed environments. The main drawback of QKD is its high cost, which comes, among others, from: i) the requirements for the quantum transmitters and receivers; and ii) the need of carefully selecting the fibers supporting the quantum channel to minimize the environmental effects that could dramatically change the polarization state of photons. In this paper, we propose a Machine Learning(ML)-based polarization tracking and compensation that is able to keep shared secret key exchange to high rates even under large fiber stressing events. Exhaustive results using both synthetic and experimental data show remarkable performance, which can simplify the design of both quantum transmitter and receiver, as well as enable the use of aerial optical cables, thus reducing total QKD system cost.
Index Terms— Machine learning | polarization-encoded quantum key distribution.
مقاله انگلیسی
8 Total fractional-order variation regularization based image reconstruction method for capacitively coupled electrical resistance tomography
روش بازسازی تصویر مبتنی بر تنظیم تغییرات مرتبه کسری کل برای توموگرافی مقاومت الکتریکی جفت شده خازنی-2021
Compared with electrical resistance tomography, capacitively coupled electrical resistance tomography (CCERT) is preferred since it avoids problems of electrode corrosion and electrode polarization. However, reconstruction of conductivity distribution is still a great challenge for CCERT. To improve reconstruction quality, this work proposes a novel image reconstruction method based on total fractional-order variation regularization. Simulation work is conducted and reconstruction of several typical models is studied. Robustness of the proposed method to noise is also conducted. Additionally, the performance of the proposed reconstruction method is quantitatively evaluated. We have also carried out phantom experiment to further verify the effectiveness of the proposed method. The results demonstrate that the quality of reconstruction has been largely improved when compared with the images reconstructed by Land weber, Newton-Raphson and Tikhonov methods. The inclusion is more accurately reconstructed and the background is much clearer even under the impact of noise.
Keywords: Capacitively coupled electrical resistance | tomography | Image reconstruction | Total fractional-order variation regularization
مقاله انگلیسی
9 Defect-engineering-enhanced electrical manipulation of anisotropic excitons in two-dimensional ReS2
دستکاری الکتریکی اکسیتون های ناهمسانگرد با نقص مهندسی در ReS2 دو بعدی-2021
Engineering the photoluminescence (PL) properties, such as emission peaks, intensity, and lifetime, is highly desirable for widespread applications. Electric control is a facile and feasible method, and electrical manipulation of the PL properties with a high efficiency becomes increasingly important. ReS2 has excellent environmental stability, distinctive interlayer decoupling, and strong anisotropic properties. Herein, taking ReS2 as a prototype material, we propose a novel strategy to enhance electrical control of anisotropic excitons in ReS2 by defect engineering. Sulfur vacancies have been introduced controllably by mild argon plasma treatment, and contribute to the anisotropic defect-related exciton emission whose polarization direction is almost the same as those of the excitons along the Re–S atomic chains. However, the conversion from the neutral excitons to the defect-related excitons significantly modulate the radiation recombination behavior under a lateral electric field. The defect engineering-enhanced electrical manipulation of anisotropic excitons paves the way towards an exciton engineering in new 2D electronic and optoelectronic devices.
Keywords: Photoluminescence | Anisotropic | Defect engineering | Electric control
مقاله انگلیسی
10 An analysis of Twitter users’ long term political view migration using cross-account data mining
تجزیه و تحلیل از مهاجرت دیدگاه های طولانی مدت کاربران توییتر با استفاده از داده های متقابل حسابداری-2021
During the 2016 US presidential election, we witnessed a polarized population and an election outcome that defied the predictions of many media sources. In this study, we conducted a follow-up on political view migration through tracking Twitter users’ account activity. The study was conducted by following a set of Twitter users over a four year period. Each year, Twitter user activities were collected and analyzed by our novel cross-account data mining algorithm. This algorithm through multiple iterations computes a numerical political score for each user based on their connection to other users and hashtags. We identified a set of seed users and hashtags using prominent political figures and movements to bootstrap the algorithm. The political score distribution demonstrates a divided population on political views. We also observed that users are more moderate in years close to elections (2017 and 2020) compared to years of none election (2018 and 2019). There is an overall migration trend from conservatives to progressives during the four years. This change in scores across the four year time frame suggests a unique political cycle exclusive to Donald Trump’s unprecedented presidential term. Our results in a broad sense portray the potential capabilities of a data collection and scoring algorithm that detected a noticeable political migration and describes the broad social characteristics of certain politically aligned users on social media platforms.
keywords: شبکه های اجتماعی | سیاست | توییتر | داده کاوی | Social networks | Politics | Twitter | Datamining
مقاله انگلیسی
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