A post about quantum entanglement.
(this is just a copy from my X/Twitter post for those who do not have access)
Someone sent this message referencing quantum entanglement. Seems like a great lead in to a post about quantum entanglement.
This is some paraphrasing of the article in the second tweet: Quantum entanglement is one of the most fascinating and perplexing phenomena in quantum mechanics, where two or more particles become linked in such a way that the state of one particle directly affects the state of the other, even when separated by vast distances.
This strange connection persists no matter how far apart the particles are, leading to instantaneous effects that seemingly violate the principles of classical physics.
The foundation of quantum entanglement is the concept of superposition, where particles can exist in multiple states simultaneously.
Imagine flipping a coin. While the coin is spinning in the air, it is in a state where it could land as either heads or tails, but it doesn’t assume a definite outcome until observed or measured.
In quantum mechanics this superposition means that the coin isn’t merely undecided, it is both heads and tails at the same time until it’s observed.
Quantum entanglement builds on superposition, but now it involves two or more particles. When particles become entangled, the measurement of one particle instantly determines the state of the other, no matter how far apart they are.
This connection occurs even if the particles are separated by distances as vast as billions of light-years. If you measure the state of one particle, the entangled partner will immediately reflect the corresponding state, as if the two were communicating faster than the speed of light.
In 1964, physicist John Bell developed what is now known as Bell’s Theorem, which demonstrated that if quantum mechanics were correct, entangled particles influence each other instantaneously across space.
This idea seemed to challenge Einstein’s theory of relativity, which holds that nothing can travel faster than the speed of light. Einstein himself referred to this instantaneous influence as “spooky action at a distance,” expressing discomfort with the implications of quantum mechanics.
Yet, numerous experiments have since validated Bell's Theorem, proving that entangled particles do behave in this "spooky" manner.
The randomness of quantum mechanics ensures that you cannot use entanglement to transmit information in a way that would violate the speed limit set by the speed of light. One of the coolest examples of quantum entanglement involves light particles, or photons.
When two photons are emitted from the same source, they can become entangled. If we measure the polarization (the direction in which the light waves oscillate) of one photon, it will tell us the polarization of the second photon, even if it’s on the other side of the universe.
Polarization refers to how the electric field of a light wave oscillates as it moves. Example: a photon can be polarized vertically or horizontally. In an entangled state, if photon A is found to have vertical polarization, photon B will also exhibit vertical polarization, even though the direction of polarization for each individual photon was entirely random before the measurement.
The key to entanglement is that the measurement outcomes of entangled particles are correlated. Even if the results seem random individually, the connection between the two particles ensures that one measurement always determines the outcome of the other. This happens even though the photons are far apart and have no way of "communicating" with each other in the conventional sense.
One of the most interesting areas of quantum physics is is quantum cryptography, where entanglement ensures secure communication. Because any attempt to measure or eavesdrop on an entangled system would disturb the particles and reveal the presence of the intruder, it offers an unprecedented level of security.
Another application is in quantum computing, where entanglement allows for vastly more powerful computations. In a traditional computer, bits can be in one of two states, 0 or 1. However, in a quantum computer, qubits can exist in superposition.
This means they represent both 0 and 1 simultaneously. When qubits are entangled, they can process a massive amount of information in parallel, far beyond what classical computers are capable of.
Entanglement has also been explored for deep-space communications. For instance, NASA’s Lunar Atmosphere Dust and Environment Explorer (LADEE) mission demonstrated the potential for sensitive superconducting nanowire single-photon detectors (SNSPDs) to improve data transmission in space. By leveraging quantum entanglement, future communication systems could allow data to be sent across vast interstellar distances much more efficiently.
Even with all of that, quantum entanglement remains a deeply mysterious and not fully understood phenomenon. The universe is far more interconnected than we previously imagined.
(this was a paraphrasing of material based on this article): https://www.space.com/31933-quantum-entanglement-action-at-a-distance.html