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StarsRuler
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¿ What´s the matter if after decoherence the measured system coherences again with the bath ¿ Is measure erased
mfb said:Decoherence cannot be reversed, otherwise it is not a proper decoherence.
"This entropy can increase but never decrease with a projective measurement, however generalized measurements can decrease entropy. The entropy of a pure state is zero, while that of a proper mixture always greater than zero. Therefore a pure state {entropy zero} may be converted into a mixture by a measurement, but a proper mixture can never be converted into a pure state. Thus the act of measurement induces a fundamental irreversible change on the density matrix; this is analogous to the "collapse" of the state vector, or wavefunction collapse."
Coherence after decoherence is a phenomenon in quantum mechanics where a system that was initially in a superposition state (i.e. having multiple possible states at the same time) becomes entangled with its environment, causing the superposition to collapse into a single state. This process is known as decoherence, and the resulting state is referred to as coherence after decoherence.
Decoherence destroys the superposition state and reduces the system to a single state. This loss of quantum coherence also leads to the loss of certain quantum properties, such as interference and entanglement, which are essential for many quantum applications.
No, coherence after decoherence cannot be reversed. Once decoherence occurs, the system is in a classical state and cannot return to a superposition state. This is due to the irreversible nature of quantum measurement, which causes the collapse of the wave function.
Coherence after decoherence can be a significant challenge in quantum computing applications. It limits the amount of time that quantum systems can maintain their superposition states, making it difficult to perform complex calculations. Scientists are currently researching ways to mitigate the effects of decoherence and improve coherence times in quantum computers.
No, coherence after decoherence can also have beneficial effects in certain cases. For example, in some quantum sensing applications, decoherence can provide a way to measure and detect tiny changes in the environment that would otherwise be undetectable. Additionally, decoherence can also help to protect quantum systems from external disturbances, which is crucial for building robust quantum technologies.