Quantum Cellular Automata (QCA) represents an emerging technology at the nanotechnology level. Nowadays, many applications of QCA technology are introduced and cryptography can be an interesting application of QCA technology. The original encryption algorithm for GSM was A5/1. Here, we have implemented the A5/1 stream cipher using QCA technology. Simulation results are obtained from software of QCA Designer.

Quantum-dot cellular automaton is a new technology for implementation of logic gates and digital circuits at nanoscale. By reducing size of the components, sensitivity of circuit increases and quantum circuits become more vulnerable to adverse environmental factors. Due to the importance of designing fault tolerant circuits, this paper presents a five-input majority gate with fault tolerance characteristic in quantum cellular automata technology. All possible faults which may occur during the process of placing cells in specific locations on the surface including displacement, deletion, rotation, and extra cell are evaluated.  In the first step, all the four types of faults are applied to the gate and the next step is to evaluate the accuracy of the gate performance with the QCADesigner simulator. In order to find such a majority gate, different methods, including the method of adding cells (the injection of redundancy to the gate) and the specific arrangement of cells are utilized. The latter method is being used more, hence, low overhead is added to the design.  The results confirm the superiority of the proposed gate over the other previously offered designs.

The state of micro or nano-scale digital circuits will be suddenly changed in case of a charged particle collision and this leads to disturbances in the operation of the circuit and the circuit will fail. These particles in electrical harsh environments can induce different effects on the circuit which these effects may be temporary or permanent in terms of performance and type of circuit and the sensitivity of the circuit to charged particles will be increased by decreasing the dimensions of the circuit. Today the nano circuits are immunized against single events with specific technologies during design and implementation of these circuits. Due to a dramatic reduction in power consumption and circuit size, Quantum cellular automata have occupied a special place in nanoelectronic and utilizing the fault tolerance methods can improve the tolerability of these circuits in harsh environments. In this paper, we present a new method to increase the fault tolerance of QCA circuits and simulation of this method for the inverter logic gate in quantum cellular automata technology.

Quantum-dot cellular automata (QCA) is a modern technology, which has higher speed, lower power consumption, higher density, and lower complexity than conventional technologies, such as CMOS. Moreover, the gate diffusion input (GDI) technique has been successful in reducing complexity, area, and energy consumption in low-power circuit designs. In this technique, a wide range of complex logic functions can be implemented using only two transistors as the main block. In this study, a QCA-based GDI block is proposed using only 11 cells as a standard design unit that can be used to implement basic functions such as AND, OR, MUX, BUFFER, NOT and XOR in digital circuits. QCADesigner simulations of the functions in 18 nm technology indicate the superior performance of the proposed block with only one clock cycle delay in performing the operations. Moreover, the power consumption analysis of the designed circuits is performed using QCADesigner. The advantages of the proposed circuit compared to previous designs are 31% reduction in cell count, 50% smaller surface area, and 17% reduction in total energy loss.

In this paper, we introduce open cellular learning automata and then study its convergence behavior. It is shown that for a class of rules called commutative rules, the open cellular learning automata in stationary external environments converges to a stable and compatible configuration. The numerical results also confirm the theory.  

In this work, oscillator strength and quantum efficiency of new spherical GaN/AlGaN quantum dot was investigated. In order to obtain these parameters, at first, Schrödinger equation is solved in GaN/AlGaN spherical coordinate system in effective mass approximation, and energy level, wave function and transition matrix element of the parameter are obtained. The results show that oscillator strength decreases with increase of mol fraction and dot size. This effect is more obvious for high mol fractions. With increasing mol fraction of defect, the peak of quantum efficiency shows blue shift. Increasing the radius of core and shell causes the red shift of quantum efficiency peak. The red and blue shifts can be very useful in tunning and controling the detector wavelenght range.

Quantum-dot cellular automata (QCA) technology is an alternative to overcoming the constraints of CMOS technology. In this paper, a new structure for D-type latch is presented in QCA technology with set and reset terminals. The proposed structure, despite having the set and reset terminals, has only 35 quantum cells, a delay equal to half a cycle of clocks and an occupied area of 39204 nm2. Then, this structure has been used to implement D-type flip-flops that are sensitive to the rising, falling, and both edges. For example, the proposed structure of the rising edge D-type flip-flop has a 55 quantum cells with a delay of 0. 75 clock cycles and an occupied area of 61404 nm2. In order to prove the proposed circuit behavior in more complex circuits, these structures have been used in the form of phase-frequency detectors, frequency dividers, and counters. Simulation of power parameters has been done for proposed structures.