Quantum decoherence is the process where a quantum system loses its quantum characteristics due to interactions with its surrounding environment. In simpler terms, it is the process by which quantum systems lose their "quantumness" and begin to behave more like classical systems.
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| Image: AI generated conceptual illustration representing phase decoherence in quantum mechanics. |
To clarify it more, imagine a perfectly balanced spinning top.
While it's spinning, it can be thought of as being in multiple states at once – it's kind of blurry and you can't pinpoint its exact position. That's similar to how things are in the quantum world, where particles can be in multiple states at the same time (called "superposition").
Now, imagine that spinning top starts bumping into things – maybe some dust particles or air currents. Those little bumps will disrupt its perfect spin making it to wobble. Eventually, it falls over and is in one definite state i.e. not spinning at all.
Quantum decoherence is like those little bumps. It's when a quantum system (like a tiny particle) interacts with its environment (like air, light, or even just the container it's in) which will "disturb" the delicate quantum state.
We can also compare it with a bubble - delicate and can easily be popped. In the quantum world, particles are like those bubbles – they're in a fragile state where they can be in multiple states at once. Now when they actually interact with their surroundings - the bubble popps. And they are in one state and become more definite.
Types
The common types of Quantum Decohorence includes
Environmental Decoherence: Caused by interactions with the surrounding environment.
Dynamical Decoherence: Due to the system's internal dynamics.
Thermal Decoherence: Resulting from thermal interactions
Applications
Quantum decoherence is a major obstacle to the development of quantum technology (such as the computers). It's because quantum computers rely on the superposition of states to perform calculations. However, if the quantum states decohere, the quantum computer will lose its ability to perform these calculations.
Examples
One of the most famous examples of quantum decoherence is Schrödinger's cat. In this thought experiment, a cat is placed in a box with a radioactive atom. If the atom decays, it will trigger a device that releases a deadly poison. According to quantum mechanics, the cat is in a superposition of being both alive and dead until the box is opened and the cat's state is measured.
However, in the real world, the cat would quickly decohere due to interactions with its environment. This means that the cat would be in a definite state of either alive or dead long before the box is opened.
The Whispering Gallery
Now, imagine you introduce some obstacles into the room: maybe some tapestries hanging on the walls, or some furniture scattered around. When you whisper, the sound waves still travel along the walls, but they now also bump into these obstacles. Each of this bump scatters the sound waves in different directions, disrupting their smooth, coherent flow.
By the time the sound reaches the other side of the room, it's much weaker and muffled, perhaps even inaudible. The original "whisper" has lost its coherence.