Why classical gates are irreversible?

In summary, the conversation discusses the concept of irreversibility in logic gates and the possibility of building reversible computers. The speaker notes that a NAND gate is irreversible due to the loss of one bit in the output, and suggests that considering one of the inputs as the output could make it reversible. They also mention the use of reversible computers in theory and as "toy" systems, but not in practical applications. The conversation ends with a thank you for the replies.
  • #1
markoX
28
0
Hi everybody.
I give you an example to clarify my question:
a NAND gate is irreversible becuase you can not find inputs from outputs and this is because of one bit is lost in output ( Antropy will increase ).the number of inputs and output are not the same in NAND gate.
ok...now my question is that we can consider one of input as output so we can make it reversible.why is'nt this true?

I have graduated in physics. thanks
 
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  • #2
markoX said:
Hi everybody.
I give you an example to clarify my question:
a NAND gate is irreversible becuase you can not find inputs from outputs and this is because of one bit is lost in output ( Antropy will increase ).the number of inputs and output are not the same in NAND gate.
ok...now my question is that we can consider one of input as output so we can make it reversible.why is'nt this true?

I have graduated in physics. thanks

There is a direction associated with the amplification that is used for the logic gate function. Look at the equivalent circuit for a logic gate, and it is apparent that the inputs are high-impedance controls (like FET gates), and the outputs are low-impedance drivers.
 
  • #3
Note that it IS of course possible to build reversible computers (in the computational sense) using classical components.
As far as I know there are no practical applications, but reversible comouters have been used as "toy" systems for a long time (this is one reason why quantum computing took off so quickly, much of the theory for reversible gates has been around for a long time).
 
  • #4
thanks for your replies.
 

1. Why are classical gates considered irreversible?

Classical gates are considered irreversible because once a gate operation has been applied to a set of inputs, it is impossible to determine the exact inputs that produced that specific output. This is due to the fact that the gate operation involves a loss of information and the output does not contain enough information to reverse the operation and retrieve the original inputs.

2. How do classical gates differ from quantum gates in terms of reversibility?

Unlike classical gates, quantum gates are reversible, meaning that the original inputs can be retrieved from the outputs by reversing the gate operation. This is possible because quantum gates use complex numbers and superposition to encode and process information, allowing for the preservation of information even after a gate operation has been applied.

3. What impact does the irreversibility of classical gates have on computing?

The irreversibility of classical gates has a significant impact on computing as it limits the potential for information storage and retrieval. This makes classical computers less efficient than quantum computers, which can perform reversible operations and potentially store and process more information.

4. Can classical gates be made reversible?

No, classical gates cannot be made reversible. The irreversibility is a fundamental property of classical gates and cannot be altered. However, there are methods such as error correction and redundancy that can be used to mitigate the effects of irreversibility in classical computing.

5. How does the irreversibility of classical gates affect the accuracy of computations?

The irreversibility of classical gates can lead to loss of information and errors in computations. This is because the outputs of gate operations do not contain enough information to determine the exact inputs, making it difficult to detect and correct errors. This is a significant challenge in classical computing, which relies on accuracy to produce reliable results.

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