DAY 8: My learning #Quantum30 Challenge
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Quantum Entanglement:
Quantum entanglement is a fundamental phenomenon in quantum physics where two or more particles become correlated in such a way that the state of one particle is dependent on the state of another, even when they are separated by large distances. This correlation is often referred to as "spooky action at a distance" by Albert Einstein.
Example: Consider a pair of entangled electrons. If one electron's spin is measured to be "up," the other electron's spin will instantaneously become "down," even if they are light-years apart. This phenomenon occurs regardless of the distance between the particles, which violates classical notions of locality.
EPR Paradox:
The EPR paradox, named after its inventors Einstein, Podolsky, and Rosen, is a thought experiment that highlights the strange consequences of quantum entanglement. It questions whether quantum mechanics provides a complete description of physical reality.
Example: Imagine two entangled particles, such as electrons, initially in a state where their total angular momentum is zero. If we measure the spin of one particle and find it to be "up," we instantly know that the other particle's spin is "down," even if it's far away. This implies that information about one particle is transmitted to the other instantly, seemingly violating the theory of relativity, which suggests that information cannot travel faster than the speed of light.
Bell's Experiment:
In Bell's experiment, when entangled quantum particles, such as electrons, pass through two detectors which have three measures in 3 directions set 120 degrees apart and each measurer get activated randomly and makes the measurement in both the detectors, and their spins are measured, an intriguing phenomenon emerges. According to the Einstein-Podolsky-Rosen (EPR) argument, if these particles harbored hidden information and detector orientations were chosen at random, there should be a 55% chance that both detectors display opposite spin directions.
Before, that observe these clearly:
Also note this diagram:
Here P is the probability measure.
Let's illustrate this with an example of hidden information for Detector A, represented as UUD (signifying "Up," "Up," "Down"), and for Detector B, it's DDU ("Down," "Down," "Up"). As measurement angles are randomly selected, nine possible combinations emerge: UD, UD, UU, UD, UD, UU, DD, DD, DU.
Out of these nine possibilities, five of them result in different spins between the detectors (UD, UD, UD, DU, DU). This would indeed yield a 55% probability of obtaining different results if classical hidden variables were responsible. However, the experimental outcomes consistently demonstrate that only 50% of measurements differ between the detectors.
This result unmistakably underscores the quantum behavior of entanglement. In entanglement, both particles share the same wave function, and measuring one particle instantaneously determines the properties of the other, even when separated by considerable distances. This contradicts the classical notion of independent hidden variables and underscores the profound interconnectedness of quantum particles through entanglement.
For more about quantum challenges and knowledge, Do visit the Quantum Computing India