How/why decoherence rather than how/why coherence

In summary, the conversation discusses the concept of decoherence and its relation to coherence in quantum entities. The speakers question whether the focus should be on explaining coherence rather than decoherence, and suggest that decoherence is a natural state of affairs while coherence is puzzling. They also touch on the idea of entanglement and its connection to decoherence.
  • #1
Gerinski
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Many discussions get around the subject of how / why does decoherence happen. Interaction with the environment, getting to macroscopic scale, irreversible change of information... Somehow they seem to imply that the natural state of things in the Universe is quantum coherence and then they ask for the mechanism which collapses that into a decoherent state (wavefunction collapse).

I wonder whether the question should not be the other way around, not so much why / how does decoherence happen but rather the opposite, why / how / what does it mean that quantum entities sometimes display coherence.

Decoherence somehow seems to be the logical state of affairs, things having definite positions, momentums, definite histories. It is rather coherence which is puzzling, things being in a superposition of different possible realities. Should we not be looking at the issue from this point of view? Not 'things are fundamentally coherent but decoherence turns them into fixed realities' but rather 'things are normally concrete realities but under certain conditions we may make several of those coexist in a superposition for a short time'? And then ask 'how / why is it so'?
 
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  • #2
If one starts from the Schrodinger equation as the starting point, then coherence is something normal and decoherence something that needs to be explained. So effectively, you ask: Why Schrodinger equation in the first place?
 
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  • #3
Gerinski said:
It is rather coherence which is puzzling, things being in a superposition of different possible realities.

Well you are reading things into it the theory is silent about.

But leaving that aside decoherence is nothing mysterious - its simply a kind of entanglement. Its pretty obvious with all the interactions we have in the world around us its very very difficult to stop happening.

Thanks
Bill
 

FAQ: How/why decoherence rather than how/why coherence

How does decoherence occur?

Decoherence is a process in which quantum systems lose their coherence and become classical. This can happen when a quantum system interacts with its environment, causing the system to become entangled with the environment and losing its quantum properties.

Why does decoherence happen?

Decoherence occurs due to the sensitive nature of quantum systems. Any interaction with the environment can cause the system to lose its coherence and behave classically. This is because the environment acts as a measuring device, constantly interacting with the system and causing it to collapse into a classical state.

How does decoherence affect quantum computing?

Decoherence is one of the major challenges in quantum computing. It can cause errors in quantum calculations and limit the ability to maintain and manipulate quantum states. Therefore, techniques such as error correction and quantum error correction codes are used to mitigate the effects of decoherence in quantum computing.

Why is decoherence important in understanding the quantum world?

Decoherence is important because it helps explain the transition from the quantum world to the classical world. It also plays a crucial role in understanding the measurement problem in quantum mechanics. Decoherence provides a bridge between the abstract concepts of quantum mechanics and the familiar classical world we experience.

How can we control decoherence?

Controlling decoherence is a major goal in quantum information science. Some techniques that have been developed to control decoherence include quantum error correction, quantum feedback control, and quantum error mitigation. Additionally, choosing suitable materials and designing quantum systems with minimal interactions with the environment can also help reduce the effects of decoherence.

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