Spooky

Nice video! Bigger font and more zoom next time please!

Very very well explained. Moreover, what is this minimum entropy cost?

@qiskit

Жыл бұрын

Thank you! The minimum entropy cost of erasing 1 bit of information is ln2, where ln is the natural logarithm (log to base e). In the classical case, this is equal to the Shannon entropy of a random coin; see the definition of Shannon entropy here: www.quantiki.org/wiki/classical-information) And in the quantum case, this is equal to the von Neumann entropy of a maximally mixed qubit; see the definition of von Neumann entropy here: www.quantiki.org/wiki/von-neumann-entropy#:~:text=and%20if%20%CE%BBi%20are,of%201%20for%20a%20qubit. The definitions of these entropies are also at the end of the Jupyter Notebook: github.com/maria-violaris/quantum-paradoxes/blob/main/quantum-maxwells-demon.ipynb. Hope that helps!

@laxmiprasadnaik7348

Жыл бұрын

@@qiskit Thankyou

In the sub-atomic scale, the deamon wouldn't be able to measure speed AND position of the particle at the same time. Heisenberg forbids this. So, there's no way to distinguish slow and fast particles, or left and right side of the box. This experiment makes lots of assumptions. According Mr. Gibbs, the entropy even increases, if you put water into a cup filled with water. Gibbs-Paradox. So, we also have to clearify the problem with indistinguishable particles. In other words, can we label these particles? For me, this rises more questions than answers.

@anothercreatureofthesea1412

Жыл бұрын

The rabbit hole you are pointing to is fascinating and has been the subject of quite a bit of research. Keep sitting with those questions! You might want to read about quantum feedback control (e.g. based on continuous measurement, in which the observer takes on a role analogous to Maxwell's demon), and/or look into any of the existing proposals for quantum engines driven by measurements; there are many in the recent literature beyond Szilard!

@Maria How do we know that whether it is a slow particle or fast moving particle if we are using a single particle?

@maria_violaris

10 ай бұрын

In the single-particle version of the thought experiment, instead of using information about whether the particle is slow-moving or fast-moving to decrease the entropy of the box, we use a different piece of information: whether the particle is on the Left of the box, or on the Right. (We could do a similar thing with many particles, and use information about their positions to get all the particles on one side of the box and create a pressure difference instead of a temperature difference. The conclusions are the same!) Hope that makes sense.

@muskankushwah2256

10 ай бұрын

@maria_violaris thanks for the reply.

rad

Isn't what Maxwell's demon does just the same as evaporative cooling?

💀

These papers which are independently claiming reversing entropy by mixing Raoult's law with osmosis principle and Extended Gibbs Donnan Equilibrium . Title of the papers: Experimental Demonstration of Energy Harvesting by Maxwell's Demon Device DOI: 10.20944/preprints202403.1698.v1 .... An Autonomous Mechanical Maxwell's Demon DOI: 10.14293/S2199-1006.1.SOR-.PP5S6NK.v1