Contents
Are classical logic gates reversible?
It’s possible to perform all classical logic operations using only reversible gates. But in those cases, often it becomes necessary to use ancilla bits. For instance, the reversible Toffoli gate gate can implement all classical logic functions. The Toffoli gate has a quantum version too.
WHY NOT gate is reversible?
The OR gate is not reversible: there are four different possible input states (00, 01, 10, 11) and only two possible output states (0 and 1), so there isn’t enough information in the output to know for sure what the inputs were.
Is NAND gate reversible?
He goes on to describe the behaviour of what he calls a reversible NAND gate: It has three inputs and three outputs. Of the outputs, two, A’ and B’, are the same as two of the inputs, A and B, but the third input works this way. C’ is the same as C unless A and B are both 1, in which case C it changes whatever C is.
What is a reversible operation in logic gates?
Reversible logic gates are defined as systems in which each possible set of inputs maps into a unique pattern of outputs; such systems do not lead to the generation of heat (5, 6). In these two gates, any set of inputs is processed and results as a unique pattern of outputs.
Do quantum computers use logic gates?
In quantum computing and specifically the quantum circuit model of computation, a quantum logic gate (or simply quantum gate) is a basic quantum circuit operating on a small number of qubits. However, it is possible to perform classical computing using only reversible gates.
Is reversible computing possible?
And if you are doing computation using such reversible gates, it is reversible computing. It is theoretically possible to build a computer completely composed of such gates, and such a system will not dissipate any heat as per thermodynamics (at least the heat generated due to irreversible computing).
Which gate is not reversible?
From common logic gates, NOT is reversible, as can be seen from its truth table below. The common AND gate is not reversible, however. The inputs 00, 01 and 10 are all mapped to the output 0. Reversible gates have been studied since the 1960s.
Which reversible gate uses 2 input and 2 output?
Optical Feynman Gate
All-Optical Feynman Gate. The Feynman gate is a 2 × 2 reversible gate shown schematically in Figure 5(a). It has 2 inputs and 2 outputs, with one input variable which is also the output.
Why are logic gates reversible?
Reversible logic has various applications in various field like in Nanotechnology, quantum computing, Low power CMOS, Optical computing and DNA computing, etc. The reversible logic is design,main purposes are-decrease quantum cost, depth of the circuits & the number of garbage output.
Which one is reversible logic gate?
A reversible logic gate is a memory-less logic element that realizes an injective logical function. Fredkin gate, Toffoli gate, interaction gate, and switch gate are typical ones. Reducing the total amount of garbage signals is an important problem in designing reversible logic circuits.
Which logic gates are reversible?
A reversible logic gate is a memory-less logic element that realizes an injective logical function. Fredkin gate, Toffoli gate, interaction gate, and switch gate are typical ones. Here, we investigate basic properties of reversible logic gates and circuits, which are needed in the following chapters.
Can a non reversible classical gate be made reversible?
In logic circuits, the Toffoli gate (also CCNOT gate), invented by Tommaso Toffoli, is a universal reversible logic gate, which means that any classical reversible circuit can be constructed from Toffoli gates.
Can a quantum gate implement a reversible logic function?
For instance, the reversible Toffoli gate gate can implement all classical logic functions. The Toffoli gate has a quantum version too. Basically, all reversible classical logic operations can be directly mapped to quantum gate operations, which are unitary and reversible.
Why are reversible gates not used in real circuits?
There are several “advertised” advantages to fredkin gates that do not necessarily work as expected in real circuits. The energy savings of reversible logic gates is due mostly to the fact that they do not require entropy be created when an operation is performed.
Is there a reversible version of the XOR gate?
Interestingly, the reversible quantum version of the XOR gate is the CNOT gate. However, there are exceptions like the classical NOT gate. For the NOT gate, if you’re given that the output state 1, then you can unambiguously say the initial state of A was 0.