A look at the light in a new light: Scientists have created an unprecedented form of matter. (translation of the article)
Scientists at Harvard and the Massachusetts Institute of Technology (MIT-MIT) change the generally accepted viewpoint about light and for this they did not have to fly to another far-away galaxy.
Working with colleagues from the Harvard-Massachusetts Center of Ultracold Atoms, a group of professor of physics at Harvard Mikhail Lukin and professor of physics at MIT Vladan Vuletic was able to start talking photons so that they would join together in the form of a molecule - a state of matter that was formerly only in pure theory. The work is described in the article Nature on September 25.
According to Lukin, the discovery reveals the ten-year generally accepted contradiction underlying the nature of light. “Photons have long been considered massless particles that do not interact with each other — after all, the glow of two laser beams just passes through each other,” he says.
“Photonic molecules,” however, do not behave quite like traditional lasers, but to a greater extent, like lightsaber in the pages of science fiction.
"Most of the known properties of light come from the fact that photons have no mass and do not interact with each other. What we did was create a special type of medium in which photons began to interact with each other so much that they begin to act as if they have mass and are bound together in molecules.
This type of state of the photon bond was theoretically discussed for a long time, but so far it has not been observed.
You should not make a direct analogy with light swords, ”adds Lukin. “When these photons interact with each other, they repel and reflect each other. The physics of what happens in these molecules is similar to what we see in the movies. ”
But it was not possible to use “The Force” to Lukin and his colleagues, including Ofer Fisterberg, Alexey Gorshkov, Tibo Peyronel and Chi-Yu Lien, had to use a set of extreme conditions.
The researchers started by pumping rubidium atoms in a vacuum chamber, then using a laser to cool a cloud of atoms to a minimum, just above absolute zero, using extremely weak laser pulses, they fired one photon into the cloud of atoms.
“After the photon leaves the environment, it retains its identity,” - Lukin. “This is similar to the effect of light refraction that we see when light passes through a glass of water. Light penetrates into the water and splashes a part of its energy in the medium, but inside it it exists as light and matter joined together, and when it comes out it continues to be light. Approximately the same process takes place here, only steeper - the light slows down a lot and releases much more energy than it does when refracted. ”
When Lukin and his colleagues released two photons into the cloud, they were surprised that the photons at the exit merged into one molecule.
What made them form an unprecedented molecule?
')
“This effect is called Rydberg’s blockade,” said Lukin, “which describes the state of the atoms when the atom is excited — neighboring atoms cannot be excited to the same extent. In practice, the effect means that as soon as two photons enter the atomic cloud, the first excites an atom, but must be ahead before the second photon can excite neighboring atoms. "
As a result, from his words, it turns out that two photons seem to be pulling and pushing each other through the cloud, while their energy spreads from one atom to another.
“This photon interaction is mediated by atomic interaction,” says Lukin. “It forces photons to behave like molecules, and when they come out of the medium, most likely they will do this together, and not as single photons.”
Although the effect is unusual for him, practical application is possible.
“We did this for fun (for fun), well, and because we are pushing the boundaries of science,” says Lukin.
“But this is included in a broader picture of what we are doing, because photons remain the best possible means for transmitting quantum information. The main disadvantage was that the photons do not interact with each other.
To build a quantum computer, ”he explains,“ researchers need to build a system that can store quantum information and process it using quantum logic operations.
But the problem was that quantum logic required interaction between individual quanta, so that these quantum systems could switch to perform information processing.
What we have demonstrated in this process will allow us to go further, ”said Harvard professor Mikhail Lukin.
“Before we get to the practical application of a quantum switch or photon logic converter, we need to improve performance, so this is still at the level of proof of concept, but this is an important step.
The physical principles we have established here are important. The system can also be useful in classical calculations, to reduce the loss of power that chip manufacturers are currently experiencing.
Some companies, including IBM, developed systems based on optical routers that convert light signals into electrical ones, but they had certain difficulties. ”
Lukin also suggested that the system could one day be used even to create a complex three-dimensional structure — such as a crystal — entirely out of light.
“For what it will be useful, we still don’t really know, but this is a new state of matter, so we are hopeful that it can be used in the process of continuing our research on the properties of these photon molecules,” he said.
Harvard University (2013, September 25). Scientists create never-before-seen form of matter. ScienceDaily. Retrieved September 25, 2013, from www.sciencedaily.com/releases/2013/09/130925132323.htm
Working with colleagues from the Harvard-Massachusetts Center of Ultracold Atoms, a group of professor of physics at Harvard Mikhail Lukin and professor of physics at MIT Vladan Vuletic was able to start talking photons so that they would join together in the form of a molecule - a state of matter that was formerly only in pure theory. The work is described in the article Nature on September 25.
According to Lukin, the discovery reveals the ten-year generally accepted contradiction underlying the nature of light. “Photons have long been considered massless particles that do not interact with each other — after all, the glow of two laser beams just passes through each other,” he says.
“Photonic molecules,” however, do not behave quite like traditional lasers, but to a greater extent, like lightsaber in the pages of science fiction.
"Most of the known properties of light come from the fact that photons have no mass and do not interact with each other. What we did was create a special type of medium in which photons began to interact with each other so much that they begin to act as if they have mass and are bound together in molecules.
This type of state of the photon bond was theoretically discussed for a long time, but so far it has not been observed.
You should not make a direct analogy with light swords, ”adds Lukin. “When these photons interact with each other, they repel and reflect each other. The physics of what happens in these molecules is similar to what we see in the movies. ”
But it was not possible to use “The Force” to Lukin and his colleagues, including Ofer Fisterberg, Alexey Gorshkov, Tibo Peyronel and Chi-Yu Lien, had to use a set of extreme conditions.
The researchers started by pumping rubidium atoms in a vacuum chamber, then using a laser to cool a cloud of atoms to a minimum, just above absolute zero, using extremely weak laser pulses, they fired one photon into the cloud of atoms.
“After the photon leaves the environment, it retains its identity,” - Lukin. “This is similar to the effect of light refraction that we see when light passes through a glass of water. Light penetrates into the water and splashes a part of its energy in the medium, but inside it it exists as light and matter joined together, and when it comes out it continues to be light. Approximately the same process takes place here, only steeper - the light slows down a lot and releases much more energy than it does when refracted. ”
When Lukin and his colleagues released two photons into the cloud, they were surprised that the photons at the exit merged into one molecule.
What made them form an unprecedented molecule?
')
“This effect is called Rydberg’s blockade,” said Lukin, “which describes the state of the atoms when the atom is excited — neighboring atoms cannot be excited to the same extent. In practice, the effect means that as soon as two photons enter the atomic cloud, the first excites an atom, but must be ahead before the second photon can excite neighboring atoms. "
As a result, from his words, it turns out that two photons seem to be pulling and pushing each other through the cloud, while their energy spreads from one atom to another.
“This photon interaction is mediated by atomic interaction,” says Lukin. “It forces photons to behave like molecules, and when they come out of the medium, most likely they will do this together, and not as single photons.”
Although the effect is unusual for him, practical application is possible.
“We did this for fun (for fun), well, and because we are pushing the boundaries of science,” says Lukin.
“But this is included in a broader picture of what we are doing, because photons remain the best possible means for transmitting quantum information. The main disadvantage was that the photons do not interact with each other.
To build a quantum computer, ”he explains,“ researchers need to build a system that can store quantum information and process it using quantum logic operations.
But the problem was that quantum logic required interaction between individual quanta, so that these quantum systems could switch to perform information processing.
What we have demonstrated in this process will allow us to go further, ”said Harvard professor Mikhail Lukin.
“Before we get to the practical application of a quantum switch or photon logic converter, we need to improve performance, so this is still at the level of proof of concept, but this is an important step.
The physical principles we have established here are important. The system can also be useful in classical calculations, to reduce the loss of power that chip manufacturers are currently experiencing.
Some companies, including IBM, developed systems based on optical routers that convert light signals into electrical ones, but they had certain difficulties. ”
Lukin also suggested that the system could one day be used even to create a complex three-dimensional structure — such as a crystal — entirely out of light.
“For what it will be useful, we still don’t really know, but this is a new state of matter, so we are hopeful that it can be used in the process of continuing our research on the properties of these photon molecules,” he said.
Harvard University (2013, September 25). Scientists create never-before-seen form of matter. ScienceDaily. Retrieved September 25, 2013, from www.sciencedaily.com/releases/2013/09/130925132323.htm
Source: https://habr.com/ru/post/195280/
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