QUANTUM
Quantum tunnelling (or tunneling) is the quantum-mechanical effect of transitioning through a classically-forbidden energy state. Consider rolling a ball up a hill. If the ball is not given enough velocity, then it will not roll over the hill. This makes sense classically. But in quantum mechanics, objects do not behave like classical objects, such as balls, do. On a quantum scale, objects exhibit wavelike behavior. For a quantum particle moving against a potential hill, the wave function describing the particle can extend to the other side of the hill. This wave represents the probability of finding the particle in a certain location, meaning that the particle has the possibility of being detected on the other side of the hill. This behavior is called tunneling; it is as if the particle has 'dug' through the potential hill.Wave/particle duality is a quantum phenomenon usually confined to photons, electrons, protons, and other ultra-tiny objects. Quantum mechanics shows that such objects sometimes behave like particles, sometimes behave like waves, and sometimes like a little of both.
All objects exhibit wave/particle duality to some extent, but the larger the object the harder it is to observe. Even individual molecules are often too large to show the quantum mechanical behavior.
Now physicists at the Université de Paris have demonstrated wave/particle duality with a droplet made of trillions of molecules.
The experiment involved an oil droplet bouncing on the surface of an agitated layer of oil. The droplet created waves on the surface, which in turn affected the motion of the droplet. As a result, the droplet and waves formed a single entity that consisted of a hybrid of wave-like and particle-like characteristics.
When the wave/droplet bounced its way through a slit, the waves allowed it to interfere with its own motion, much as a single photon can interfere with itself via quantum mechanics.
Although the wave/droplet is clearly a denizen of the classical world, the experiment provides a clever analogue of quantum weirdness at a scale that is much easier to study and visualize than is typical of many true quantum experiments.Quantum teleportation has been experimentally demonstrated by physicists at the University of Innsbruck. First proposed in 1993 by Charles Bennett of IBM and his colleagues, quantum teleportation allows physicists to take a photon (or any other quantum-scale particle, such as an atom), and transfer its properties (such as its polarization) to another photon -- even if the two photons are on opposite sides of the galaxy.
Note that this scheme transports the particle's properties to the remote location and not the particle itself. And as with Star Trek's Captain Kirk, whose body is destroyed at the teleporter and reconstructed at his destination, the state of the original photon must be destroyed to create an exact reconstruction at the other end.
In the Innsbruck experiment, the researchers create a pair of photons A and B that are quantum mechanically "entangled": the polarization of each photon is in a fuzzy, undetermined state, yet the two photons have a precisely defined interrelationship. If one photon is later measured to have, say, a horizontal polarization, then the other photon must "collapse" into the complementary state of vertical polarization.
In the experiment, one of the entangled photons A arrives at an optical device at the exact time as a "message" photon M whose polarization state is to be teleported. These two photons enter a device where they become indistinguishable, thus effacing our knowledge of M's polarization (the equivalent of destroying Kirk).
What the researchers have verified is that by ensuring that M's polarization is complementary to A's, then B's polarization would now have to assume the same value as M's. In other words, although M and B have never been in contact, B has been imprinted with M's polarization value, across the whole galaxy, instantaneously.
This does not mean that faster-than-light information transfer has occurred. The people at the sending station must still convey the fact that teleportation had been successful by making a phone call or using some other light-speed or sub-light-speed means of communication. While physicists don't foresee the possibility of teleporting large-scale objects like humans, this scheme will have uses in quantum computing and cryptography.
All objects exhibit wave/particle duality to some extent, but the larger the object the harder it is to observe. Even individual molecules are often too large to show the quantum mechanical behavior.
Now physicists at the Université de Paris have demonstrated wave/particle duality with a droplet made of trillions of molecules.
The experiment involved an oil droplet bouncing on the surface of an agitated layer of oil. The droplet created waves on the surface, which in turn affected the motion of the droplet. As a result, the droplet and waves formed a single entity that consisted of a hybrid of wave-like and particle-like characteristics.
When the wave/droplet bounced its way through a slit, the waves allowed it to interfere with its own motion, much as a single photon can interfere with itself via quantum mechanics.
Although the wave/droplet is clearly a denizen of the classical world, the experiment provides a clever analogue of quantum weirdness at a scale that is much easier to study and visualize than is typical of many true quantum experiments.Quantum teleportation has been experimentally demonstrated by physicists at the University of Innsbruck. First proposed in 1993 by Charles Bennett of IBM and his colleagues, quantum teleportation allows physicists to take a photon (or any other quantum-scale particle, such as an atom), and transfer its properties (such as its polarization) to another photon -- even if the two photons are on opposite sides of the galaxy.
Note that this scheme transports the particle's properties to the remote location and not the particle itself. And as with Star Trek's Captain Kirk, whose body is destroyed at the teleporter and reconstructed at his destination, the state of the original photon must be destroyed to create an exact reconstruction at the other end.
In the Innsbruck experiment, the researchers create a pair of photons A and B that are quantum mechanically "entangled": the polarization of each photon is in a fuzzy, undetermined state, yet the two photons have a precisely defined interrelationship. If one photon is later measured to have, say, a horizontal polarization, then the other photon must "collapse" into the complementary state of vertical polarization.
In the experiment, one of the entangled photons A arrives at an optical device at the exact time as a "message" photon M whose polarization state is to be teleported. These two photons enter a device where they become indistinguishable, thus effacing our knowledge of M's polarization (the equivalent of destroying Kirk).
What the researchers have verified is that by ensuring that M's polarization is complementary to A's, then B's polarization would now have to assume the same value as M's. In other words, although M and B have never been in contact, B has been imprinted with M's polarization value, across the whole galaxy, instantaneously.
This does not mean that faster-than-light information transfer has occurred. The people at the sending station must still convey the fact that teleportation had been successful by making a phone call or using some other light-speed or sub-light-speed means of communication. While physicists don't foresee the possibility of teleporting large-scale objects like humans, this scheme will have uses in quantum computing and cryptography.
diposting oleh ANDIK MEINDRA @ 23.24
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