## No full-text available

To read the full-text of this research,

you can request a copy directly from the authors.

To read the full-text of this research,

you can request a copy directly from the authors.

Reversible gate has been one of the emerging research areas that ensure continual process of innovation trends that explore and utilizes the resources. Due to the increasing power consumption of electronic circuits, it has been observed that quantum computing is one of its latest applications. This technology can be utilized by reducing the energy consumption by preserving the bits of information that are still useful. A photon has zero rest mass, while an electron has a nonzero rest mass. These characteristics inspired the researchers to develop an all-optical Fredkin gate. The proposed gate design overcomes the shortcomings of conventional Fredkin gates and provides better performance.

Quantum-dot is the result of elastic relaxation which has a straight relationship with the optical and electronic aspects of the quantum-dot-based devices. In nanotechnologies, Quantum-dot Cellular Automata (QCA) is a perfect transistor-less computation method where it tries to create general computation at the nanoscale with better switching frequency and enhanced scale integration to overcome the scaling shortfalls of CMOS technology. In this technology, binary information is represented based on the distribution of electron configuration in chemical molecules. Also, the comparator is the essential component in digital circuits, which takes two binary numbers as input and implements their resemblance. In this paper, a 1-bit comparator architecture in an optimized and efficient manner is suggested to bring a new phase of comparator circuit based on QCA, and then a novel 2-bit comparator structure is offered. The simulation and functionality of proposed comparators have been examined by the QCAdesigner tool, and comparison with formerly designs shows a high degree of compactness and consistent performance of proposed designs. Proposed 1-bit and 2-bit QCA comparators exhibit a delay of 0.75 and 2.75 clock cycle, occupy an active area of 0.04 and 0.19 μm2, and use 31 and 125 QCA cells, respectively.

The atomistic quantum-dot cellular automata (QCA) based implementations of the reversible circuits have got tremendous exposures in the last few days, due to “room-temperature workability” of the QCA. The researchers are in serious need of a methodology that can realize the area-efficient QCA counterparts of reversible benchmark circuits. In this work, a novel methodology named majority-layered T hybridization is proposed to synthesize the reversible circuits using QCA. Firstly the reversible library consisting of CNTS Gates have been generated to validate the usability of the proposed methodology. Then, an elementary QCA module of 3×3 Toffoli Gate have been proposed and extended in the realization of 4×4, 5×5 and 6×6 Toffoli Gates (multi-control Toffoli Gates). The proper mathematical modelling of the several QCA design metrics like effective area, delay and O-cost has been established. The QCA counterpart of 3×3 Toffoli Gate reports 18.61% less effective area and 8.33% less O-cost compared to the previous Toffoli Gate designs. Moreover, the QCA layout of rd-32 reversible benchmark using multi-control Toffoli Gate has been employed to verify the scalability and reproducibility of the proposed methodology. The QCA layouts are generated, tested and simulated by renowned computer aided design tool QCADesigner 2.0.3.

Quantum dot Cellular Automata (QCA) is an emerging technology for development of logic circuits based on nanotechnology, and is one of the alternative for designing high performance computing over existing CMOS-VLSI technology. QCA does not use voltage level for logic representation rather it represents binary state by polarization of electrons in the QCA Cell. Conventional logic circuits are irreversible in nature and always lead to energy dissipation. Thus extensive research is going on to design the circuits which does not dissipation the energy and hence will not loose the information. In this paper we have designed the QCA based toffoli gate and then implemented the basic logic gates with it. The circuits were successfully simulated and verified by QCA Designer tool.

Quantum Dot Cellular Automata (QCA) is a rising innovation which seems to be a good competitor for the next generation of digital systems and widely utilized as a part of advanced frameworks. It is an appealing substitute to ordinary CMOS innovation because of diminutive size, faster speed, extremely scalable feature, ultralow power consumption and better switching frequency. The realization of quantum computation is not possible without reversible logic. Reversible logic has enlarged operations in quantum computation. Generally reversible computing is executed when system composes of reversible gates. It has numerous fields of use as applied science, quantum dot cellular automata as well as low power VLSI circuits, low power CMOS, digital signal processing, computer graphics. In this paper, the quantum implementation of primitive reversible gate has been presented. The proposed gates have been designed and simulated using QCADesigner.

Quantum-dot cellular automata (QCA) are nanoscale digital logic constructs that use electrons in arrays of quantum dots to carry out binary operations. In this paper, a basic building block for QCA will be proposed. The proposed basic building block can be customized to implement classical gates, such as XOR and XNOR gates, and reversible gates, such as CNOT and Toffoli gates, with less cell count and/or better latency than other proposed designs.

Quantum dot Cellular Automata (QCA) is one of the emerging nanotechnologies, promising alternative to CMOS technology due to faster speed, smaller size, lower power consumption, higher scale integration and higher switching frequency. The basic element in QCA is majority gate. This paper, present two different design layout of Toffoli gate based on QCA logic gates: majority voter gate (MV), QCA wire and inverter gate. QCADesigner, a common QCA layout design and verification tool is employed to verify and simulate the proposed Toffoli Gate (TG). The simulation result confirmed the correctness of the proposed circuits. The proposed circuit has a promising future in constructing of nano-scale low power exhausting information processing system and can stimulate higher digital applications in QCA.

Quantum-dot Cellular Automata (QCA) is a new technology for development of logic circuits based on nanotechnology, and it is an one of the alternative for designing high performance computing over existing CMOS technology. The basic logic in QCA does not use voltage level for logic representation rather it represent binary state by polarization of electrons on the Quantum Cell which is basic building block of QCA. Extensive work is going on QCA for circuit design due to low power consumption and regularity in the circuit.. Clocking is used in QCA circuit to synchronize and control the information flow and to provide the power to run the circuit. Reversible logic design is a well-known paradigm in digital computation, and if circuit developed is reversible then it consumes very low power . Here, in this paper we are presenting a Reversible Universal Gate (RUG) based on Quantum-dot Cellular Automata (QCA). The RUG implemented by QCA Designer tool and also its behavior is simulated by it.

The quantum-dot cellular automata (QCA) which is the most promising technology in the paradigm of nano electronics has already been claimed to possess ultra-high packing density, high clocking speed and extremely low power dissipation. This work proposes a novel design of high fan-in exclusive-OR gate by using the layered T Gate of QCA. The 'robustness analysis' of layered T gate has also been done to focus the advantage of layered T architecture in generic sense considering the defects of QCA. The synthesis of 'three-literal standard functions' by using layered T gate reports an average 29.31% less area requirement as compared to the best reported design so far. Primarily two-input layered T exclusive OR shows 18.75% less cell requirement and 6.20% less area requirement as compared to the conventional two-input exclusive OR designs. Finally, two-input layered T exclusive OR module extends its design methodology to implement high fan-in exclusive OR gate designs with proper formulation of O-Cost and delay in QCA.

The size of complementary metal oxide semiconductor (CMOS) transistor keep shrinking to increase the density on chip in accordance with Moore's Law [1]. The scaling affect the device performance due to constraints like heat dissipation and power consumption [3], further scaling would hit the physical limitation [16]. Effortshave been made to come up with the new device alternative to CMOS, to continually improve the development of electronic device. Quantum Dot Cellular Automata (QCA) technology is one such promising alternative, that can overcome the scaling issue and offer fast computation performance, high density, and low power consumption. Another emerging technology that can help in reducing heat dissipation is reversible logic. This paper proposes the idea of implementing reversible combinational circuits and square computation circuits using QCA architecture. The designs are captured and simulated using QCA Designer software, performance of each designs namely area and energy are compared for conventional and Reversible QCA design.

The development of low power systems gained significant importance and impressive progress has been made in this domain in the recent years. However, despite more efficient circuit technologies (made possible e.g. by the ongoing miniaturization of integrated circuits) as well as improvements in battery technology, also the way how computations are logically performed may have an effect on the required power consumption. In this invited paper, we consider reversible computation - an alternative computation paradigm which inherits certain characteristics and properties that may be of benefit for low power design. We review possible impacts to future developments and show how reversible computations can already been exploited today. Finally, we sketch design challenges which, besides other physical and electrical issues, still prevent the full exploitation of this computation paradigm.

This study introduces a novel architecture for image steganography using reversible logic based on quantum dot cellular automata (QCA). Feynman gate is used to achieve the reversible encoder and decoder for image steganography. A Nanocommunication circuit for image steganography is shown using proposed encoder/decoder circuit. The proposed QCA circuits have lower quantum cost than traditional designs. It shows the cost effectiveness functionality of the proposed designs. The proposed circuit has 28.33% improvement in terms of area over complementary metal-oxide-semiconductor circuit. To perform image steganography LSB technique is used; signal-tonoise ratio (SNR), peak SNR and mean squared error (MSE) are also computed. The proposed QCA encoder/decoder circuit is suitable for reversible computing. To establish this, the heat energy dissipation by the proposed encoder/ decoder circuit is estimated. The estimation shows that the encoder/decoder circuit has very low energy dissipation. Single missing/additional cell-based defect analysis is also explored in this study. Reliability of the circuit is tested against different temperatures. Implementation and testing of the circuit are achieved using QCADesigner tool. MATLAB is used to produce the input to the proposed circuit.

Both quantum-dot cellular automata (QCA) and reversible logic are emerging technologies that are promising alternatives to overcoming the scaling and heat dissipation issues, respectively, in the current CMOS designs. Here, the fundamentals of QCA and reversible logic are studied; the feasibility of incorporating reversible logic in QCA designs is also demonstrated. Based on two existing designs, an improved version of the reversible gates, namely the Feynman Gate and the Toffoli Gate, were implemented in QCA technology using QCADesigner. The proposed design of the QCA-based Feynman Gate is faster by 1/2 cycle as compared to the existing design; while the proposed Toffoli Gate has the same latency as the existing design but it is readily to be cascaded into a more complex design. A 4-bit ripple carry adder in QCA is then designed using the proposed Feynman and Toffoli gates to realize a reversible QCA full adder. This 4-bit QCA adder with reversible logic consists of 2030 QCA cells, has a latency of 7 clock cycles and 8 garbage outputs.

Fast changing world has driven technology towards a milestone where emerging technology like quantum-dot cellular automata (QCA) excels in terms of ultra-high packing density and extremely low power consumption. Quantum Cellular Automata has several deduction methodologies like Majority Voter, Universal QCA logic, FNZ logic & And-Or-Invert (AOI) logic none of which explores universal NAND-NOR based design in Boolean reduction techniques. This work proposes Layered T full adder with its basic primitive which works on the basis of universal NAND and NOR logic. Layered T gate is verified taking Coulomb's law as the physics behind it. Layered T Gate is also used to implement full adder as primitive in processor based design which gives the best result in terms of cell requirement and area compared to the latest design.

This work presents a novel implementation of reversible gates and reversible ALU, all based in quantum-dot cellular automata (QCA). QCA has been considered as an alternative for field-effect transistors due to its quite small size (nanometers), ultra-low power consumption and clock rate (terahertz range). On the other hand, reversible computation is a new paradigm where all logic operations can be performed in an invertible way. This feature is important to different technologies, such as quantum computing, adiabatic circuits, low power computation, etc. Regarding low power consumption, QCA has been seen as a promising technology for approaching the thermodynamic limit of computation and this work focus on designing a QCA reversible ALU in order to go beyond that limit, bridging the gap between QCA technology and reversible components. In a bottom-up approach, we first discuss QCA reversible gates and a few design choices. We also present the ALU's QCA design, demonstrate the functionality, test and validate the proposed architecture using QCADesigner simulator. Due to the importance of these new computational paradigms, this study is central in consolidating possible emerging technologies.

A Quantum-dot Cellular Automata (QCA) device having normal QCA cells laid out in a planar structure such that there are a set of input lines, that may be columns, and a set of orthogonal, output lines, that may be rows. The device has clocking regions that control the flow of binary signals through the device. The input columns are driven by a separate input signal, and all the cells of each column align to match their input signal. These input columns then serve as drivers for output rows that act as serial shift registers under the control of clock signals applied to sub-sections of the rows. In this way, a copy of the contents of each of the input signals propagates along each of the output rows to an output cell. The output cells of each output row may be assigned their own, latching clock signal.

Computing processes are ultimately abstractions of physical processes; thus, a comprehensive theory of computation must reflect in a stylized way aspects of the underlying physical world. On the other hand, physics itself may draw fresh insights and productive methodological tools from looking at the world as an ongoing computation. The terminformation mechanics seems appropriate for this unified approach to physics and computation.

The usual general-purpose computing automaton (e.g., a Turing machine) is logically irreversible—its transition function lacks a single-valued inverse. Here it is shown that such machines may be made logically reversible at every step, while retaining their simplicity and their ability to do general computations. This result is of great physical interest because it makes plausible the existence of thermodynamically reversible computers which could perform useful computations at useful speed while dissipating considerably less than kT of energy per logical step. In the first stage of its computation the logically reversible automaton parallels the corresponding irreversible automaton, except that it saves all intermediate results, thereby avoiding the irreversible operation of erasure. The second stage consists of printing out the desired output. The third stage then reversibly disposes of all the undesired intermediate results by retracing the steps of the first stage in backward order (a process which is only possible because the first stage has been carried out reversibly), thereby restoring the machine (except for the now-written output tape) to its original condition. The final machine configuration thus contains the desired output and a reconstructed copy of the input, but no other undesired data. The foregoing results are demonstrated explicitly using a type of three-tape Turing machine. The biosynthesis of messenger RNA is discussed as a physical example of reversible computation.

Implementing the Toffoli Gate in quantum-dot cellular automata

- B Cvetkovska
- I Kostadinovska
- J Danek