Why does Landauer define erasure of information as resetting

It's not clear to me how this differentiates Bennett's proposal from Landauer's.In summary, Landauer's principle says that resetting a device to 0 before measuring it requires kBTln2 of heat production. Bennett's proposal says that measurement doesn't require any work at all.
  • #1
Hi. I hope this is the right forum for the question.

Landauer's principle says that the erasure of one bit of information (1 or 0) requires kBTln2 of heat production. When he talks about erasure, it means "resetting back to 0 (or 1)" after measuring. He says something along "this is needed as to not to bias the device". I guess this means "for the device to perform a measure, it needs to previously be in a given state". So that if you need to measure 0's and 1's, it intrinsically needs to be restored to 0 before each new measure. Why?
  • #4
I have an answer to the question, but still there's something quite open to me. Erasure means resetting so that it doesn't interfere the device operation. For example, if a device with a one bit memory controls a door and is instructed to "OPEN DOOR whenever a measure gives 1", it wouldn't work if it wasn't resetted to 0.

However, focus now on the picture I'm uploading:

The right side of the red line is the resetting procedure, which resets a bit to 0 no matter what its state is. Calculations have shown this procedure implies, on average, a work of W=kTln2 on the particle (particle is brownian, and so disippates it into heat).

The left side is what Bennett proposed for a measure of a bit of information, saying measurement requires no work done. Worry not about the procedure he thought of, the important part is that it can be represented as a double well potential being modulated like is indicated next to the figure.

...Notice something similar? I find both modulations of the potential to be quite the same, yet the left one is an example of no expenditure of energy and the right one is just the opposite. What am I missing?

Edit: "Medida" means measurement.


  • Doble pozo medida Bennet-Borrado de Landauer.png
    Doble pozo medida Bennet-Borrado de Landauer.png
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  • #6
Yes, I know. A process where the memory of the device takes a state (1 or 0 if its a one bit memory) which corresponds to a given physical variable of the system being measured.

1. Why does Landauer define erasure of information as resetting?

Landauer defines erasure of information as resetting because it involves the process of eliminating or removing a specific state or value that represents information. This is similar to resetting a computer or device to its original state, erasing any existing data or information.

2. How does erasure of information relate to the concept of entropy?

Erasure of information is closely related to the concept of entropy, which is a measure of the disorder or randomness in a system. When information is erased, the system becomes more ordered and the entropy decreases. This is because the number of possible states or configurations of the system decreases as information is removed.

3. Can erasure of information be reversed?

In theory, erasure of information can be reversed by restoring the system to its previous state or value. However, in practice, it is often impossible to completely reverse the erasure process, as some information may be lost or become irretrievable.

4. How does the Landauer principle apply to erasure of information?

The Landauer principle states that there is a minimum amount of energy required to erase a bit of information. This means that erasure of information is not a completely reversible process, as some energy is always lost in the form of heat. The Landauer principle also helps to explain the connection between information and thermodynamics.

5. Is erasure of information important in modern technology?

Yes, erasure of information is a crucial concept in modern technology and plays a role in many devices and systems, such as computer memory, hard drives, and data storage. Understanding erasure of information is essential for designing efficient and reliable technologies that can store and manipulate information accurately.

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