Shahid Qamar

Sliding Mode Control for Coupled-Tank Liquid Level Control System

This paper presents the mathematical modeling of coupled-tank system and designing of sliding mode control (SMC) for liquid level control in the system. The non-linear single-input single-output (SISO) mathematical model of plant is developed initially. A simulation is carried out using MATLAB/SIMULINK to control the non-linear model of coupled-tank system for a number of different conditions. The commanded inputs such as that of step, random, square, saw tooth and sinusoidal input signals are fed to the system to test the tracking performance of SMC. Some realistic situations are also included in the plant to examine the robustness of controller. The controller showed robustness for disturbance in the plant and produced an appropriate control signals for the sake of controlling the liquid level in the coupled tank system. The tracking performance of SMC is also compared with conventional PID controller in terms of performance index ITAE. The SMC showed excellent tracking results than PID controller for time varying command signals.

Observing the quantum interference using phase-sensitive amplification

We show that a coherent superposition of coherent states remains highly nonclassical when it is amplified through a linear phase-sensitive or phase-insensitive amplifier. The nonclassicality persists for arbitrarily large gain. We also propose a scheme for the observation of quantum interference via phase-sensitive amplification. The basic idea is to amplify a Schrodinger-cat state through a phase-sensitive two-photon CEL amplifier such that there is no added noise in the quadrature of interest and all the noise is fed into the conjugate quadrature. This scheme allows us to avoid the problem of detector efficiency in balanced homodyne detection.

Adaptive Wavelets Based Fuzzy NN Control for Active Suspension Model

The objective of this paper is to examine the performance of full car active suspension system by using adaptive wavelet fuzzy-neural network (WFNN) control strategy. The conventional passive suspension system does not provide the passenger comfort and vehicle handling against the road disturbances. In order to improve the passenger’s comfort and vehicle’s handling an adaptive WFNN is used for full car suspension. WFNN consists of fuzzy linguistic rules. WFNN has more accurate and generalized approximations for non-linear functions. The performance of WFNN is examined as compared to semi-active and passive suspension systems. Simulation is based on the full car mathematical model by using MATLAB/SIMULINK.

Three-qubit Grover's algorithm using superconducting quantum interference devices in cavity-QED

We present a scheme for the implementation of three-qubit Grover’s algorithm using four-level superconducting quantum interference devices (SQUIDs) coupled to a superconducting resonator. The scheme is based on resonant, off-resonant interaction of the cavity field with SQUIDs and application of classical microwave pulses. We show that adjustment of SQUID level spacings during the gate operations, adiabatic passage, and second-order detuning are not required that leads to faster implementation. We also show that the marked state can be searched with high fidelity even in the presence of unwanted off-resonant interactions, level decay, and cavity dissipation.

Neuro-fuzzy wavelets based network for full car active suspension system

In this paper, a nonlinear adaptive neuro-fuzzy wavelets network (NFWN) control strategy is designed for the control of full car suspension system. Conventional passive suspension system has not the ability to provide better vehicle stability and ride quality against the road disturbances. To avoid damaging from vehicle components, passenger discomfort and vehicle instability, an active suspension system based on NFWN is used. The active NFWN controller is capable of providing better ride quality and vehicle stability, because, it is highly nonlinear control strategy and has ability to overcome the oscillations produced due to road disturbances. Simulation is based on the mathematical model by using MATLAB/SIMULINK. Simulation results of NFWN control strategy give better tradeoff between ride quality and vehicle stability than passive and semi-active suspension systems.

Adaptive Fuzzy Wavelet NN Control Strategy for Full Car Suspension System

In the last few years, different linear and non-linear control techniques have been applied by many researchers on the vehicle suspension system. The basic purpose of suspension system is to improve the ride comfort and better road handling capability. Therefore, a comfortable and fully controlled ride can not be guaranteed without a good suspension system. The suspension system can be categorized as; Passive, Semi-active and Active.

Adaptive Neuro-fuzzy Sliding Mode Control Based Strategy for Active Suspension Control

Suspension system of a vehicle is used to minimize the effect of different road disturbances on ride comfort and to improve the vehicle control. A passive suspension system responds only to the deflection of the strut. While, the semi active system setup can dissipate energy from the system at an appropriate time, in a way or amount that is right for all the variables in the system. The main objective of this work is to design an efficient active suspension control for full car model with 8-Degrees of Freedom (DOF) using adaptive soft computing technique. So, in this study, an Adaptive Neuro-Fuzzy based Sliding Mode Control (ANFSMC) is used for full car active suspension system to improve the ride comfort and vehicle stability. ANFSMC is adapted in such a way as to estimate online the unknown dynamics and provide feedback response. The detailed mathematical model of ANFSMC has been developed and successfully applied to a full car model. The robustness of the presented ANFSMC has been proved on the basis of different performance indices. The analysis of MATLAB/SMULINK based simulation results reveals that the proposed ANFSMC has better ride comfort and vehicle handling as compared to passive or semi-active suspension systems.

Entanglement in a parametric converter

In this paper, we consider a parametric converter as a source of entangled radiation. We examine recently derived conditions (Hillery and Zubairy 2006 Phys. Rev. Lett. 96 050503, Duan et al 2000 Phys. Rev. Lett. 84 2722) for determining when the two output modes in a parametric converter are entangled. We show that for different initial field states, the two criteria give different conditions that ensure that the output states are entangled. We also present an input–output calculation for the entanglement of the output field.

Realization of quantum gates with multiple control qubits or multiple target qubits in a cavity

We propose a scheme to realize a three-qubit controlled phase gate and a multi-qubit controlled NOT gate of one qubit simultaneously controlling n-target qubits with a four-level quantum system in a cavity. The implementation time for multi-qubit controlled NOT gate is independent of the number of qubit. Three-qubit phase gate is generalized to n-qubit phase gate with multiple control qubits. The number of steps reduces linearly as compared to conventional gate decomposition method. Our scheme can be applied to various types of physical systems such as superconducting qubits coupled to a resonator and trapped atoms in a cavity. Our scheme does not require adjustment of level spacing during the gate implementation. We also show the implementation of Deutsch–Joza algorithm. Finally, we discuss the imperfections due to cavity decay and the possibility of physical implementation of our scheme.

Multiqubit quantum phase gate using four-level superconducting quantum interference devices coupled to superconducting resonator

Abstract In this paper, we propose a scheme to realize three-qubit quantum phase gate of one qubit simultaneously controlling two target qubits using four-level superconducting quantum interference devices (SQUIDs) coupled to a superconducting resonator. The two lowest levels ∣0〉 and ∣1〉 of each SQUID are used to represent logical states while the higher energy levels ∣2〉 and ∣3〉 are utilized for gate realization. Our scheme does not require adiabatic passage, second order detuning, and the adjustment of the level spacing during gate operation which reduce the gate time significantly. The scheme is generalized for an arbitrary n -qubit quantum phase gate. We also apply the scheme to implement three-qubit quantum Fourier transform.