Physicists Irreversibly Split Photons By Freezing Them In a Bose-Einstein Condensate (phys.org) 50
Physicists from the University of Bonn and the University of Cologne have succeeded in cooling photons down to a Bose-Einstein condensate, causing the light to collect in optical "valleys" from which it can no longer return. The findings have been published in the journal Science. Phys.Org reports: A light beam is usually divided by being directed onto a partially reflecting mirror: Part of the light is then reflected back to create the mirror image. The rest passes through the mirror. "However, this process can be turned around if the experimental set-up is reversed," says Prof. Dr. Martin Weitz from the Institute of Applied Physics at the University of Bonn. If the reflected light and the part of the light passing through the mirror are sent in the opposite direction, the original light beam can be reconstructed. The physicist investigates exotic optical quantum states of light. Together with his team and Prof. Dr. Achim Rosch from the Institute for Theoretical Physics at the University of Cologne, Weitz was looking for a new method to generate optical one-way streets by cooling the photons: As a result of the smaller energy of the photons, the light should collect in valleys and thereby be irreversibly divided. The physicists used a Bose-Einstein condensate made of photons for this purpose, which Weitz first achieved in 2010, becoming the first to create such a "super-photon."
A beam of light is thrown back and forth between two mirrors. During this process, the photons collide with dye molecules located between the reflecting surfaces. The dye molecules "swallow" the photons and then spit them out again. "The photons acquire the temperature of the dye solution," says Weitz. "In the course of this, they cool down to room temperature without getting lost." By irradiating the dye solution with a laser, the physicists increase the number of photons between the mirrors. The strong concentration of the light particles combined with simultaneous cooling causes the individual photons to fuse to form a "super-photon," also known as Bose-Einstein condensate. "Perhaps quantum computers might one day use this method to communicate with each other and form a kind of quantum Internet," says Weitz.
A beam of light is thrown back and forth between two mirrors. During this process, the photons collide with dye molecules located between the reflecting surfaces. The dye molecules "swallow" the photons and then spit them out again. "The photons acquire the temperature of the dye solution," says Weitz. "In the course of this, they cool down to room temperature without getting lost." By irradiating the dye solution with a laser, the physicists increase the number of photons between the mirrors. The strong concentration of the light particles combined with simultaneous cooling causes the individual photons to fuse to form a "super-photon," also known as Bose-Einstein condensate. "Perhaps quantum computers might one day use this method to communicate with each other and form a kind of quantum Internet," says Weitz.
Computers might communicate with this (Score:2)
and it'll a provide a faster, more secure way to transfer lolcat videos, furry porn, humongous javascript-infested web pages, ads and corporate surveillance data. I just can't wait.
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and it'll a provide a faster, more secure way to transfer lolcat videos, furry porn, humongous javascript-infested web pages, ads and corporate surveillance data. I just can't wait.
You think that's bad, wait until Ticketmaster gets hold of this ...
But light already is bosons! (Score:1)
Maybe I'm misreading this but the beginning of TFS makes no sense.
A BEC is when you turn fermions, as in, matter, into something that acts like bosons, aka force-carriers with no Pauli exclusion. It makes zero sense to say you condensed photons into a BEC, as they already are bosons!
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The first successful experiments with photons that were called a BEC were achieved in the 90's.
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https://scholar.google.com/sch... [google.com]
Well, do you have any arguments with that statemem (Score:2)
Like a definition that differs from the one I was given from (the German edition of) Scientific American articles, PBS SpaceTime and Wikipedia.
Because we can hit each other with argumentum ad populum fallacied all day, but it will not be very useful. ;)
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Someone notes that your definition is not used and cites the preferred one so it must be an ad populum.
With that logic I suppose vaccines also do cause autism and Earth is flat after all.
If you manage to pull out your head out of your own ass, at the end of the day you will realize that we need definitions that are accepted by many for successful communication.
That's what protocols do in technical communication.
That's why we have conventions and official notations in mathematics, eve
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Interesting take. Someone notes that your definition is not used and cites the preferred one so it must be an ad populum. With that logic I suppose vaccines also do cause autism and Earth is flat after all
Hold up, I'm pretty sure autism actually causes vaccines. Also, the earth obviously isn't flat, I used my phone app and it said -3deg. How these aren't the populist opinion, I'll never know.
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You must have misread at least one of those definitions. From Wikipedia [wikipedia.org]:
A Bose-Einstein condensate (BEC) is a state of matter of a dilute gas of low densities called bosons cooled to temperatures very close to absolute zero (-273.15 degC). Under such conditions, a large fraction of bosons occupy the lowest quantum state, at which point microscopic quantum phenomena, particularly wavefunction interference, become apparent macroscopically. A BEC is formed by cooling a gas of extremely low density, about one-hundred-thousandth (1/100000) the density of normal air, to ultra-low temperatures.
The only situation where this involves fermions is in superconductivity (or equivalent), where electrons (which are fermions) form Cooper pairs and these pairs (which are bosons) condense in the BEC state.
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I think the question which arises from the original article is what is the difference between a laser beam and a bose einstein condensate.
In other words: Photons always form a BEC. (Score:2)
As they have no Pauli exclusion. Due to being bosons.
What would non-bosonic photons even be?
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It's complicated. Photons do not interact with each other, only themselves, except maybe in this condensate form. I don't know, that's well beyond my quantum fu. Just one thing to think about: according to relativity, no two photons can have the same velocity because each is moving at the speed of light in relation to the other. Makes it kind of hard to interact, and gives some hint why this condensate is special.
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"Bose–Einstein condensation (BEC)—the macroscopic ground-state accumulation of particles with integer spin (bosons) at low temperature and high density—has been observed in several physical systems1,2,3,4,5,6,7,8,9, including cold atomic gases and solid-sta
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Obviously when you split a photon you will get two fermions because of conservation of spin. TFS makes zero sense so it is a boson itself hence if you split the article in two you will get two fermions which will cancel out with the photons above and the leftover will have sense.
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Nobody splits a photon, photons are indivisible. If that text appears in the article, it is wrong.
gobbledygook buzzword soup (Score:4, Interesting)
I have not read the scientific paper but this write up of it makes it sure sound like a load of rubbish. Emission of photons from excited dye molecules imples a population inversion which isn't usually how one describes cooling in a conventional sense. One might consider these even to be negative temperatures but that's ill defined thermodynamic where many conventional conceptions go wrong and the language we normally use introduces confusion.
Additionally people conflate so many ideas about what is a photon? When photon is interacting with matter we might call this a photon but thats sort of a factorization of the shrodinger equation into terms that look like a conventional photon, terms that look like matter and a whole bunch of cross terms we hope are really small so that terms like "dipole" and "polarization" are useful to describe the additional phenomena that happens beyond just plain ole photons and ye olde matter. BUt when all those cross terms get as big as the ordinary terms then it's not really a photon. All sorts of weird shit happens and if you keep saying it's a photon then you are fitting a square peg into a round hole language wise.
And when describing coupled entangledments of photons, singling out the photon again gets goofy.
Reminds me of all the nonsense spoken about Vortex light. Vortex light does not have orbital angular momentum because photon orbital angular moment is something entirely different. Yet people talk that way and it's confusing. There's a simple irrefutable proof that vortex light isn't a new form of light with orbital angular momentum, its just a different basis set with the same number of degrees of freedom as ordniary light. Yet the aura of mystery in discussing becomes buzzword enriched. beyond comprehension
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Almost like nobody really understands quantum mechanics, particularly journalists, hmm?
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A BEC is when you turn fermions, as in, matter, into something that acts like bosons, aka force-carriers with no Pauli exclusion. It makes zero sense to say you condensed photons into a BEC, as they already are bosons!
No, you're thinking of something else. A Bose-Einstein condensate is made from bosons, it refers to what happens when all (or most) the bosons in a gas occupy the lowest possible quantum state [wikipedia.org]. You may be thinking of Cooper pairs [wikipedia.org], which is a different phenomenon were paired fermions form bosons (which could then go on to form a BEC if you want).
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It makes zero sense to say you condensed photons into a BEC, as they already are bosons!
They make it clear that this "super photon" is a boson made out of multiple photons. Not much else is clear to me, but at least that is clear.
Speaking as a lay person (Score:1)
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No, because mass is equivalent to energy, and energy has an appropriately equivalent mass. (A hypothetically perfectly reflective box with pure vacuum inside will weigh less than an identical box which contains only massless photons. The photons have energy, and are constantly bouncing around inside; This trapped energy has a real effective mass, which changes the mass of the system.)
https://physics.stackexchange.... [stackexchange.com]
As long as neither the energy of the combined system, or the mass of the combined system (a
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What? (Score:2)
What does it mean to "reconstruct the beam"? Align the photons so they act like waves again as if in a slit experiment? What property is now impossible by being in this BEC?
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Just finished reading the paper (Score:1)
I just finished reading the paper and I only have one question: what is a "photon"? I'm sure after I understand that I will understand all the rest.
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Solve that one and the Nobel Prize for Physics is yours for the taking.
Particle, wave, both depending on circumstance or something we can't really comprehend, no one really knows.
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I can't even understand the summary, so I think a Nobel Prize might be better off with someone else.
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I suspect the further down the rabbit hole of physics we go the less our monkey brains will understand it until eventually we get to a point that even geniuses simply Don't Get It. Perhaps super intelligent AI in the future will take understanding further, who knows.
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Fermi; Feynman, Tomogawa and Schwinger; Hansch, Glauber and Hall already got their Nobel prizes. All did work that more and more precisely defined the photon and the quantum mechanical states involved in electromagnetism.
Plus of course Einstein who started it all off by inventing the idea and maybe the name, and the theory of the laser.
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Well, a photon is a unit of light.
You see, you get a wavelength and it exists as a wave.
Either that or you get a particle and it exists as a moving particle.
Or you realize the very act of measurement changes things, and knowing the position means you don't know the energy levels and motion and vice versa.
Think of this as a Barney song: "Every photon likes to dance. It can either wear some pants, or it can just dance and dance."
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In classical electromagnetics there is a vector valued electric and magnetic field everywhere in space. Depending on the boundary conditions you can make a summation expansion of the 'modes' of the fields consisting of complex-valued coefficients and spatially extended waves.
In Maxwell's classical electrodynamics, those coefficients can take on any value, but in quantum mechanics, that's no longer true. There are certain discrete values that will exist. No
Quantum magic (Score:4, Funny)
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Question (Score:2)
What does it mean to "cool" a photon? Since the magnitude of its velocity is constant, does this just mean that a high-energy (i.e., short-wavelength) photon becomes a low-energy (i.e., long-wavelength) photon?
Or is there a subtlety I am missing?
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> or at least hidden
It seems to be available here:
https://sci-hub.tw/10.1126/sci... [sci-hub.tw]
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Although photons do have energy E=h*v (Planck's constant times the photon frequency). That energy you could a thermal energy E=kB*T (Boltzmann constant times absolute temperature) and solve for T=(h*v)/(kB). You know, the same 'nonsense' they do when they assign photons a momentum that is expressed in mass times velocity, although the invariant mass of a photon is zero.
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What does it mean to "cool" a photon?
Lower its frequency?
Interesting (Score:1)
"causing the light to collect in optical "valleys" from which it can no longer return. "
I always thought only farts could never return.
Body gas (Score:2)
I always thought that you could call one back in by breathing heavily and filtering it through your lungs?
Can no longer return (Score:2)
I do not think that word means what you think it means.
Try running an experiment that lasts a few million years, repeatedly, and I might believe you.
Layman's Terms (Score:2)
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Bose Einstein condensation is interesting because usually the quantum mechanical effects that distinguish quantum behavior from classical physics (stuff engineering usually uses) are tiny and only observable in fine, detailed exp
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. What is a practical example of what this can do?
Generate money for future research.