Universal Reversible Logic Gate Research Articles

Fredkin gates in simple reversible cellular automata

In this paper, we give a survey on the problem of how a Fredkin gate, a universal reversible logic gate, is realised in various reversible cellular automata (RCAs). Models of RCAs considered here are two kinds of square partitioned cellular automata (SPCAs), and four kinds of elementary triangular partitioned cellular automata (ETPCAs). These six RCAs are very simple, in particular, ETPCAs are extremely simple, yet they are computationally universal in the sense any reversible Turing machine, which is composed of Fredkin gates, can be embedded in them. There are three key points for implementing a Fredkin gate in an RCA: (1) realising a signal, (2) routeing a signal, and (3) interacting two signals. We shall see that depending on the properties of the RCAs, different techniques are used to realise the above three functions. Based on these techniques, complete configurations of Fredkin gates in the six RCAs are given.

Power analysis attack resistable hardware cryptographical circuit design using reversible logic gate in quantum cellular automata

Quantum-dot cellular automata (QCA) technology leads to rapid high-density combinatory low power exploitation to realize the reversible logic circuit in the nanoscale era. Reversible logic is an alternative to overcome excess energy indulgence of irreversible process. This paper illustrates a cost-effective, energy-efficient Universal Reversible Logic Gate in QCA framework which is capable of designing power analysis attack resistable hardware cryptographical circuit. The proposed (URLGs: U1 and U2) has been tested with simulator QCADesigner V2.0.3, outshined the existing pattern relating to the area, gate count, garbage count, and quantum cost. We found 37.5% garbage minimization is achieved compared to NFT, which is utmost minimization of garbage ever reported in QCA literature. Thirteen three variable standard Boolean functions are considered as logic benchmarks to guesstimate the capability and efficiency of proposed URLG in QCA circuit implementation and synthesizing logic gates. In average, our proposed U2 achieved 36.66% improvement in energy dissipation for different kink energy ratios over early reported work.

Theoretical approach of developing a frequency-encoded reversible optical arithmetic and logic unit using semiconductor optical amplifier-based polarization switches

The reversible logic gate is a great choice for designing various types of optical processors due to so many advantageous aspects of it; such as low power consumption and the ability of data recovery. At first, the optical circuit of Fredkin gate, a universal reversible logic gate, is designed theoretically using a semiconductor optical amplifier (SOA)-based polarization switch, and the performance of the circuit is studied using simulated results. The frequency-encoded binary data are used to execute the operations. Subsequently, we propose the techniques of developing NOT, AND, OR, EX-OR, EX-NOR gates, and full adder circuit using reversible Fredkin gates. Finally, we develop an optical arithmetic logic unit using the proper combination of reversible Fredkin gates. The theory of nonlinear polarization rotation of the probe beam in the presence of the pump beam in SOA is adopted here. The simulated input–output spectra of the optical circuits enhance the admissibility of the proposed concept.

Valleytronics in merging Dirac cones: All-electric-controlled valley filter, valve, and universal reversible logic gate

Despite much anticipation of valleytronics as a candidate to replace the ageing CMOS-based information processing, its progress is severely hindered by the lack of practical ways to manipulate valley polarization all-electrically in an electrostatic setting. Here we propose a class of all-electric-controlled valley filter, valve and logic gate based on the valley-contrasting transport in a merging Dirac cones system. The central mechanism of these devices lies on the pseudospin-assisted quantum tunneling which effectively quenches the transport of one valley when its pseudospin configuration mismatches that of a gate-controlled scattering region. The valley polarization can be abruptly switched into different states and remains stable over semi-infinite gate-voltage windows. Colossal tunneling valley-pseudo-magnetoresistance ratio of over 10,000\% can be achieved in a valley-valve setup. We further propose a valleytronic-based logic gate capable of covering all 16 types of two-input Boolean logics. Remarkably, the valley degree of freedom can be harnessed to resurrect logical-reversibility in two-input universal Boolean gate. The (2+1) polarization states -- two distinct valleys plus a null polarization -- re-establish one-to-one input-to-output mapping, a crucial requirement for logical-reversibility, and significantly reduce the complexity of reversible circuits due to the built-in nature of valley degree of freedom. Our results suggest that the synergy of valleytronics and digital logics may provide new paradigms for valleytronic-based information processing and reversible computing.

Realization of an ultrafast all-optical Toffoli logic gate based on the phase relation between two second order nonlinear optical signals

A Toffoli logic gate (CCNOT gate) is a universal reversible logic gate from which all other reversible gates can be constructed. It has a three-bit input and output. The goal of our work was to realize a Toffoli gate where all inputs and outputs are realized optically, which allows for ultrafast switching processes. We demonstrate experimentally that a Toffoli logic gate can be created based on nonlinear multi-wave interactions of light with matter. Using femtosecond laser pulses, the all-optical Toffoli gate is based on the coherence of the optical signals produced via the nonlinear optical processes. Sum frequency (SF) and second harmonic (SH) generations are combined in such a way so as to yield the complete truth table of the universal reversible logic gate.

Constructing Online Testable Circuits Using Reversible Logic

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> With the advent of nanometer technology, circuits are more prone to transient faults that can occur during its operation. Of the different types of transient faults reported in the literature, the single-event upset (SEU) is prominent. Traditional techniques such as triple-modular redundancy (TMR) consume large area and power. Reversible logic has been gaining interest in the recent past due to its less heat dissipation characteristics. This paper proposes the following: 1) a novel universal reversible logic gate (URG) and a set of basic sequential elements that could be used for building reversible sequential circuits, with 25% less garbage than the best reported in the literature; (2) a reversible gate that can mimic the functionality of a lookup table (LUT) that can be used to construct a reversible field-programmable gate array (FPGA); and (3) automatic conversion of <emphasis emphasistype="italic">any</emphasis> given reversible circuit into an online testable circuit that can detect <emphasis emphasistype="italic">online</emphasis> any single-bit errors, including soft errors in the logic blocks, using theoretically proved minimum garbage, which is significantly lesser than the best reported in the literature. </para>

On figures of merit in reversible and quantum logic designs

Five figures of merit including number of gates, quantum cost, number of constant inputs, number of garbage outputs, and delay are used casually in the literature to compare the performance of different reversible or quantum logic circuits. In this paper we propose new definitions and enhancements, and identify similarities between these figures of merit. We evaluate these measures to show their strength and weakness. Instead of the number of gates, we introduce the weighted number of gates, where a weighting factor is assigned to each quantum or reversible gate, based on its type, size and technology. We compare the quantum cost with weighted number of gates of a circuit and show three major differences between these measures. It is proved that it is not possible to define a universal reversible logic gate without adding constant inputs. We prove that there is an optimum value for number of constant inputs to obtain a circuit with minimum quantum cost. Some reversible logic benchmarks have been synthesized using Toffoli and Fredkin gates to obtain their optimum values of number of constant inputs. We show that the garbage outputs can also be used to decrease the quantum cost of the circuit. A new definition of delay in quantum and reversible logic circuits is proposed for music line style representation. We also propose a procedure to calculate the delay of a circuit, based on the quantum cost and the depth of the circuit. The results of this research show that to achieve a fair comparison among designs, figures of merit should be considered more thoroughly.

Single spin Toffoli–Fredkin logic gate

The Toffoli–Fredkin (TF) gate is a universal reversible logic gate capable of performing logic operations without dissipating energy. Here, we show that a linear array of three quantum dots, each hosting a single electron, can realize the TF gate, if we encode logic bits in the spin polarization of the electrons and allow nearest neighbor exchange coupling. The dynamics of the TF gate is realized by selectively driving spin resonances in the coupled spin system with an ac magnetic field. The conditions for gate operation are established, and an estimate of the switching speed and gate error are provided.