Increasing miniaturization and demand of low power electronics is highly motivating research on reversible logic. Reversible logic has attracted signification attention in fields of Low power VLSI design, computer graphics, quantum computing and communication. A lot of work has been done on synthesis and optimization of reversible circuits followed by quantitative analysis on various optimization metrics like ancillary inputs, garbage outputs and quantum cost. It is therefore obvious to present a quick guide on reversible logic implementation to bridge gap between theory and implementation. Taxonomy diagrams of work done in reversible logic domain are also presented to give a quick review of all about reversible logic. Quantum realization of popular reversible Fredkin gates using RCViewer tool is also presented which will be stepping stone for a new researcher to synthesize and optimize any complex reversible logic based circuit.
Increasing miniaturization and demand of low power electronics is highly motivating research on reversible logic. Reversible logic has attracted signification attention in fields of Low power VLSI design, computer graphics, quantum computing and communication. A lot of work has been done on synthesis and optimization of reversible circuits followed by quantitative analysis on various optimization metrics like ancillary inputs, garbage outputs and quantum cost. It is therefore obvious to present a quick guide on reversible logic implementation to bridge gap between theory and implementation. Taxonomy diagrams of work done in reversible logic domain are also presented to give a quick review of all about reversible logic. Quantum realization of popular reversible Fredkin gates using RCViewer tool is also presented which will be stepping stone for a new researcher to synthesize and optimize any complex reversible logic based circuit.
Reversible logic circuits have been historically motivated by theoretical research in low-power, and recently attracted interest as components of the quantum algorithm, optical computing and nanotechnology. However due to the intrinsic property of reversible logic, traditional irreversible logic design and synthesis methods cannot be carried out. Thus a new set of algorithms are developed correctly to synthesize reversible logic circuit. This paper presents a comprehensive literature review with comparative study on heuristic based reversible logic synthesis. It reviews a range of heuristic based reversible logic synthesis techniques reported by researchers (BDD-based, cycle-based, search-based, non-search-based, rule-based, transformation-based, and ESOP-based). All techniques are described in detail and summarized in a table based on their features, limitation, library used and their consideration metric. Benchmark comparison of gate count and quantum cost are analysed for each synthesis technique. Comparing the synthesis algorithm outputs over the years, it can be observed that different approach has been used for the synthesis of reversible circuit. However, the improvements are not significant. Quantum cost and gate count has improved over the years, but arguments and debates are still on certain issues such as the issue of garbage outputs that remain the same. This paper provides the information of all heuristic based synthesis of reversible logic method proposed over the years. All techniques are explained in detail and thus informative for new reversible logic researchers and bridging the knowledge gap in this area.
Reversible logic circuits have been historically motivated by theoretical research in low-power, and recently attracted interest as components of the quantum algorithm, optical computing and nanotechnology. However due to the intrinsic property of reversible logic, traditional irreversible logic design and synthesis methods cannot be carried out. Thus a new set of algorithms are developed correctly to synthesize reversible logic circuit. This paper presents a comprehensive literature review with comparative study on heuristic based reversible logic synthesis. It reviews a range of heuristic based reversible logic synthesis techniques reported by researchers (BDD-based, cycle-based, search-based, non-search-based, rule-based, transformation-based, and ESOP-based). All techniques are described in detail and summarized in a table based on their features, limitation, library used and their consideration metric. Benchmark comparison of gate count and quantum cost are analysed for each synthesis technique. Comparing the synthesis algorithm outputs over the years, it can be observed that different approach has been used for the synthesis of reversible circuit. However, the improvements are not significant. Quantum cost and gate count has improved over the years, but arguments and debates are still on certain issues such as the issue of garbage outputs that remain the same. This paper provides the information of all heuristic based synthesis of reversible logic method proposed over the years. All techniques are explained in detail and thus informative for new reversible logic researchers and bridging the knowledge gap in this area.
Summary form only given, as follows. With the increasing emphasis on low-power design and quantum computation, research activities in the area of reversible logic synthesis and testing have gained momentum over the last couple of decades. It is expected that reversible logic will provide us with a viable alternative to building ultra-low power circuits and systems in not too distant future. In the classical works for synthesis of reversible circuits, gate libraries comprising of standard reversible gates like NOT, CNOT, TOFFOLI, FREDKIN, etc. are considered. To evaluate the goodness of a synthesized netlist, various metrics such as gate count, quantum cost, and equivalent transistor cost have been considered by various researchers. The synthesis approaches that have been reported can be broadly categorized into three groups: (a) exact synthesis approaches which try to obtain optimal reversible gate netlists, but can be used for small circuits only, (b) heuristic based approaches which try to utilize some domain knowledge intelligently to reduce the complexity of search, and can be used for somewhat larger circuits, and (c) synthesis approaches that rely on higher level functional representations like binary decision diagram (BDD) or exclusive sum-ofproducts (ESOP). The last approach is scalable to larger circuits (with 200 inputs or more), however, the synthesized netlist is not optimal and various rule-based heuristic approaches have been proposed to minimize the cost. There have been works also that report techniques for implementing sequential circuits with reversible properties, which will be useful for building complex systems containing finite-state machines. There are various transformations that are carried out as part of cryptographic algorithms that are inherently reversible in nature. For instance, any block cipher that uses a key K to transform a plaintext P into a ciphertext C during encryption must be reversible, because decryption will be doing just the reverse (C to P). Also, in standard symmetric block ciphers like DES or AES, there is a combinational block called substitution box or S-box which is also reversible in nature. In AES, the S-box has 8 inputs and 8 outputs, and implements a one-to-one onto mapping. The same reversibility requirements hold for stream ciphers and public-key ciphers like RSA. Although not much work has been carried out in the area of reversible implementations of cryptographic algorithms, this can be a very good area for future research. Similar considerations hold for various coding and decoding techniques used in communication, which are also inherently reversible in nature. Some examples of such coding/decoding are Manchester, Differential Manchester, Bipolar AMI, 4B/5B, 8B/10B, Hamming error correcting code, etc. All these techniques can potentially be implemented using reversible logic circuits. Specific case studies of some of the areas as mentioned will be reported, with synthesis results.
Abstract — Reversible logic is one of the most vital issue at present time and it has different areas for its application, those are low power CMOS, quantum computing, nanotechnology, cryptography, optical computing, DNA computing, digital signal processing (DSP), quantum dot cellular automata, communication, computer graphics. It is not possible to realize quantum computing without implementation of reversible logic. The main purposes of designing reversible logic are to decrease quantum cost, depth of the circuits and the number of garbage outputs. This paper provides the basic reversible logic gates, which in designing of more complex system having reversible circuits as a primitive component and which can execute more complicated operations using quantum computers. The reversible circuits form the basic building block of quantum computers as all quantum operations are reversible. This paper presents the data relating to the primitive reversible gates which are available in literature and helps researches in designing higher complex computing circuits using reversible gates.
Reversible logic is expanding grounds with its applicability to various upcoming technologies and quantum computation. Numerous reversible gates has also been proposed for designing logic circuits apart of basic quantum controlled Toffoli and Fredkin gates. A comparative study and analysis of a range of reversible gates from the literature is presented in this paper to obtain an optimal solution for designing these circuits. The gates are synthesized and implemented to obtain equivalent quantum circuits and operating cost in terms of number of inputs, gate cost, quantum cost, garbage output and ancilla input. The comparison is done at two subsequent levels i.e. gates structural level and circuit design level, providing a better solution for designing logic circuits. It is calculated that, basic gates are 50% efficient at gate level and 33% at design level analysis in terms of gate cost, as compared to the most efficient gates proposed in the literature.
Complex computing environment is switching from peta scale to exa scale. Conventional irreversible logic will not be going to sustain forever and power dissipation need to be controlled. Lot of research is going on to avoid power dissipation due to switching but only a few research efforts have been applied on power dissipation due to loss of bits. Reversible computing is found to be one of the emerging and promising technologies to overcome addressed power dissipation due to loss of bits. Quantum cost is one of important metric of comparison and required further for analyzing performance of one reversible logic based circuit over other. This paper proposes the algorithm to draw optimized quantum implementation of reversible logic gates and further utilized for investigation of quantum cost. The optimized quantum cost obtained from proposed method is verified using RCViewer+ tool.