Elektrik Elektronik Mühendisliği Bölümü Yayın Koleksiyonu
Permanent URI for this collectionhttps://hdl.handle.net/20.500.12416/411
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Article Citation - WoS: 4Citation - Scopus: 5Accurate Method To Calculate Noise Figure in a Low Noise Amplifier: Quantum Theory Analysis(Elsevier Sci Ltd, 2022) Salmanogli, Ahmad; Gecim, H. SelcukIn this study, a low-noise amplifier is quantum-mechanically analyzed to study the behavior of the noise figure. The analysis view has been changed from classic to quantum, because using quantum theory produces some degrees of freedom, which may be ignored when a circuit is analyzed using classical theory. For this purpose, the Lagrangian is initially derived by considering the related nonlinearity of the transistor, and then using the Legendre transformation and canonical quantization procedure, the quantum Hamiltonian is derived. As an interesting point of this study, the low-noise amplifier is deliberately considered as two oscillators connecting to each other to share the photonic modes between them; accordingly, the voltage and current as measurable observations and the noise figure as a critical quantity in a low-noise amplifier are theoretically expressed in terms of the oscillator's mean photon number. The main goal of this work is to study quantities such as the noise figure in a sufficient detail using quantum theory. In addition, as an advantage of this theory, one can control and manipulate the noise figure only by manipulation of the oscillator's mean photon number and coupling it between two oscillators. Finally, the circuit is classically designed and simulated to verify the derived results using quantum theory. The comparison results show that there is a partial consistency between the two approaches; as the frequency increases, the noise figure becomes minimized at a particular frequency.Article Quantum Dot Transition Rate Modifying by Coupling To Lattice Plasmon(Springer, 2023) Salmanogli, Ahmad; Gecim, H. Selcuk; Hatem, SudeIn this study, a plasmonic system coupled to a quantum dot is defined to generate the entanglement between two non-simultaneous emitted output modes. The quantum dot with three energy levels creates two different transition rates by which non-simultaneous photons are emitted. Thus, it seems that the entanglement between two emitted modes is forbidden. However, the simulation results show the entanglement between the output modes. It is because the original transition rates of the quantum dot are modified due to the lattice plasmon coupling effect. It means that the effective transition rate affected by the lattice plasmon plays a key role. The lattice plasmon coupling to quantum dot at some locations leads to a simultaneous transition by which the entanglement between output modes is established. The entangled output modes refer to the entangled photons with a specific frequency (e.g., the emission frequency). This unique behavior is theoretically discussed and the results show that using the lattice plasmon can change the transition rates by which the two emitted modes become entangled.