Our computing era has been working long to get a solution for the problem of power dissipation in conventional digital circuitry.Towards this approach, reversible logic has received a significant attention in recent past.Power dissipation occurs due to the loss of information carrying bits during circuit simulation which consequently deteriorates the system performance.Reversible logic allows us to determine the outputs from the inputs and also the inputs can be appropriately recovered from the outputs by using one-to-one mapping.This results in reduced bit loss leading to reduced power dissipation.Reversible logic has been a research paradigm in the field of low-power CMOS, nanotechnology etc.This paper gives a brief description of few reversible logic gates and describes a mathematical derivation to verify how V and V+ gates are square root of NOT gate and Hermitian conjugate of V gate respectively, by using matrix manipulations.
Our computing era has been working long to get a solution for the problem of power dissipation in conventional digital circuitry.Towards this approach, reversible logic has received a significant attention in recent past.Power dissipation occurs due to the loss of information carrying bits during circuit simulation which consequently deteriorates the system performance.Reversible logic allows us to determine the outputs from the inputs and also the inputs can be appropriately recovered from the outputs by using one-to-one mapping.This results in reduced bit loss leading to reduced power dissipation.Reversible logic has been a research paradigm in the field of low-power CMOS, nanotechnology etc.This paper gives a brief description of few reversible logic gates and describes a mathematical derivation to verify how V and V+ gates are square root of NOT gate and Hermitian conjugate of V gate respectively, by using matrix manipulations.
This work presents the logical reversibility. The inputs and outputs of reversible logic gates can be uniquely retrievable from each other. The reversible logic operations can't erase information and dissipate zero heat. The circuit actually operates in a backward operation, allows reproducing the inputs from the outputs and consumes zero power. As the basic elements of any logic circuit, logic gates are used to realize Boolean functions. By combining reversible logic gates, reversible circuits can perform complex logical and arithmetic operations. A one-to-one mapping between inputs and outputs is realized. The logical operations run backwards by cascading a reversible logic gate with its dual (inverse). Reversible circuits are also called lossless circuits, as there is neither energy loss nor information loss. These circuits are very attractive for applications where extremely low power consumption, or heat dissipation, is desirable in areas ranging from communications, low power VLSI (very large-scale integration) technology, optical computing to nanotechnology. Reversible logic found to be very useful in quantum computing where the quantum evolution is inherently reversible.
Nowadays, reversible computing is more fascinative research area to curtail power dissipation in comparison of conventional computing. In conventional computing, logic circuit dissipates more power by losing bits of information. Reversible computing recovers from losing bits of information through same number of output vector from same number of input vector and thus decreases the power dissipation. Since there are different cost considerations such as garbage outputs, gate count, quantum cost methods for specific cost reductions may be established.
In recent years, reversible logic circuits have applications in the emerging field of digital signal processing, optical information processing, quantum computing and nano technology. Reversibility plays an important role when computations with minimal energy dissipation are considered. The main purpose of designing reversible logic is to decrease the number of reversible gates, garbage outputs, constant inputs, quantum cost, area, power, delay and hardware complexity of the reversible circuits. This paper reveals a comparative review on various reversible logic gates. This paper provides some reversible logic gates, which can be used in designing more complex systems having reversible circuits and can execute more complicated operations using quantum computers. Future digital technology will use reversible logic gates in order to reduce the power consumption and propagation delay as it effectively provides negligible loss of information in the circuit. Keywords: Garbage output, Power dissipation, quantum cost, Reversible Gate, Reversible logic,
Reversible logic is emerging as a promising computing paradigm with applications in ultralow power nanocomputing and emerging nanotechnologies such as quantum computing, quantum dot cellular automata (QCA), optical computing, etc. Reversible circuits are similar to conventional logic circuits except that they are built from reversible gates. In reversible gates, there is a unique, one-to-one mapping between the inputs and outputs, not the case with conventional logic. One of the primary motivations for adopting reversible logic lies in the fact that it can provide a logic design methodology for designing ultra-low power circuits beyond KTln2 limit for those emerging nanotechnologies in which the energy dissipated due to information destruction will be a significant factor of the overall heat dissipation. Further, logic circuits for quantum computers must be built from reversible logic components. Several important metrics need to be considered in the design of reversible circuits the importance of which needs to be discussed. Quantum computers of many qubits are extremely difficult to realize thus the number of qubits in the quantum circuits needs to be minimized. This sets the major objective of optimizing the number of ancilla inputs and the number of the garbage outputs in the reversible logic based quantum circuits. The constant input in the reversible quantum circuit is called the ancilla input, while the garbage output refers to the output which exists in the circuit just to maintain one-to-one mapping but is not a primary or a useful output. The reversible circuit has other important parameters of quantum cost and delay which need to be optimized.
At present days , reversible logic circuits have many applications in the field of optical information processing, digital signal processing , nano technology and quantum computing . Reversible logic plays an important role when computations with minimum energy dissipation are considered. The purpose of designing reversible logic is to decrease the number of area, power, garbage outputs , constant inputs, quantum cost, reversible gates, delay and hardware complexity . This paper reveals a review on some reversible logic gates, which is useful in designing more complex systems having reversible circuits and can do execution of more complex operations using quantum computers. In upcoming days digital technology will be using reversible logic gates in order to reduce the propagation delay and power consumption as it provides negligible loss of information in the circuit. Keywords: Reversible Gate, Garbage output, quantum cost, Reversible logic, Power dissipation
It has been realized that quantum computing is one of the latest technologies using reversible logic. It is observed that increasing growth of transistor density, power consumption will reach their limits in conventional technologies. In conventional Circuits during the logic operations bits of information is erased resulting dissipation of energy in significant amount. Thus, if Circuits are designed so that information bits can be preserved, the power use can be reduced. In case of reversible logic computation, the information bits are not lost. We can use reversible logic technology for minimizing the power consumption, heat dissipation, increasing speed etc. This paper describes various logic gates based on reversible logic like Toffoli, Peres, Fredkin, and Feynman etc. A comparative between classical and quantum logic gates is also given on various parameters along with limitations of conventional computing.