Does decoherence prevent 100% of quantum tunneling of macro object?

In summary, the article explores whether decoherence can completely prevent quantum tunneling in macroscopic objects. It discusses how decoherence, which involves the loss of quantum coherence due to interactions with the environment, does reduce the probability of tunneling but does not eliminate it entirely. The phenomenon is analyzed within the context of quantum mechanics, emphasizing that while decoherence plays a significant role in suppressing tunneling events, it cannot fully negate the underlying quantum mechanical principles that allow for tunneling to occur, even in larger systems.
  • #1
Kinker
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Does quantum decoherence absolutely prevent quantum tunneling of macroscopic objects?
(Decoherence) macro world and quantum world difference
Isn't the quantum tunneling probability of macroscopic objects always zero due to quantum decoherence? It may be possible in the microscopic world, but I always think it is impossible in the macroscopic world due to countless interactions. Isn't this the same in a universe with infinite time? So isn't the probability of a macroscopic object tunneling by chance always zero, regardless of the duration?
 
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Kinker said:
So isn't the probability of a macroscopic object tunneling by chance always zero, regardless of the duration?
No, it is a very very small non-zero probability.

Consider a similar purely classical setup: There is a table sitting on the floor in front of me, my feet are resting on it. The air molecules above and below it are randomly bouncing around from thermal motion. There is a very very small non-zero probability that all the air molecules above and below the table will just randomly happen to all be moving upwards at the same moment, and if this happens the table will blast its way through the roof like an artillery shell, ripping my feet off and leaving me with bloody stumps at the ends of my legs. The probability of this happening is something like ##2^{(10^{24})}##, we are comfortable saying that it's not going to happen.

The probability of a chair-sized macroscopic object tunneling through a wall is much much less than that.
 
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  • #3
Nugatory said:
No, it is a very very small non-zero probability.

Consider a similar purely classical setup: There is a table sitting on the floor in front of me, my feet are resting on it. The air molecules above and below it are randomly bouncing around from thermal motion. There is a very very small non-zero probability that all the air molecules above and below the table will just randomly happen to all be moving upwards at the same moment, and if this happens the table will blast its way through the roof like an artillery shell, ripping my feet off and leaving me with bloody stumps at the ends of my legs. The probability of this happening is something like ##2^{(10^{24})}##, we are comfortable saying that it's not going to happen.

The probability of a chair-sized macroscopic object tunneling through a wall is much much less than that.
Does that mean that macroscopic objects can also accidentally experience quantum coherence?
 
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  • #4
@Kinker You are trying to distinguish between the propositions “It could happen but it won’t” and “It can’t happen”. I’m not sure they are distinguishable.
 

FAQ: Does decoherence prevent 100% of quantum tunneling of macro object?

What is quantum decoherence?

Quantum decoherence is the process by which a quantum system loses its quantum coherence, meaning it transitions from a superposition state to a mixture of states due to interactions with its environment. This effectively causes the system to behave more classically, as the interference effects that are characteristic of quantum systems are suppressed.

Can decoherence completely prevent quantum tunneling for macroscopic objects?

Decoherence can significantly reduce the probability of quantum tunneling for macroscopic objects, but it does not completely prevent it. The probability becomes so small that for all practical purposes, it is effectively zero. However, in principle, quantum tunneling is a fundamental quantum mechanical process and cannot be entirely ruled out.

How does the size of an object affect its susceptibility to quantum tunneling and decoherence?

The larger the object, the more it interacts with its environment, leading to faster decoherence. This makes quantum tunneling extremely unlikely for macroscopic objects because the coherence time (the time over which quantum effects are significant) is very short. For microscopic particles, decoherence is much slower, allowing quantum tunneling to be a more observable phenomenon.

What role does the environment play in decoherence and quantum tunneling?

The environment plays a crucial role in decoherence by interacting with the quantum system and causing it to lose coherence. These interactions can include collisions with particles, electromagnetic radiation, and other forms of noise. As decoherence increases, the likelihood of observing quantum tunneling decreases, especially for larger systems that have more environmental interactions.

Are there any experiments that demonstrate the effects of decoherence on quantum tunneling of macroscopic objects?

While direct experiments on macroscopic objects tunneling are extremely challenging due to the rapid decoherence, there have been experiments on mesoscopic systems (systems that are larger than atoms but not quite macroscopic) that show the effects of decoherence. These experiments often involve superconducting circuits or large molecules where quantum effects can still be observed, but decoherence plays a significant role in their behavior.

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