Scientists examine possibility of a phonon laser, or 'phaser'

Sep 07, 2010 By Lisa Zyga feature
In the three physical processes of the phonon laser scheme, (a) a red-detuned laser cools the gas, (b) a blue-detuned laser pumps the ultra-cold gas, and (c) the atoms in the gas emit coherent phonons and then decay into a lower energy state. The process is similar to how an optical laser generates coherent photons. Image credit: J. T. Mendonca, et al. ©2010 Institute of Physics.

(PhysOrg.com) -- While the optical laser celebrated its 50th anniversary earlier this year, some scientists have been working on a new type of coherent beam amplifier for sound rather than light. Scientists theorize that phonons, which are the smallest discrete unit of vibrational energy, can be amplified by a phonon laser to generate a highly coherent beam of sound (particularly, high-frequency ultrasound), similar to how an optical laser generates a highly coherent beam of light. However, phonon laser research is still a relatively new area. In a new study, scientists have for the first time demonstrated the possibility that phonons can be collectively excited in an ultra-cold atomic gas in a way that is similar to how an optical laser excites photons, prompting the scientists to call the proposed device a "phaser."

The first theoretical laser was proposed one year ago, in 2009, by a team of scientists (Kerry Vahala, et al.) from the Max Planck Insitute and Caltech. In that study, the scientists outlined for the first time how a single magnesium ion can be cooled to a temperature of about 1 milli-Kelvin in an electromagnetic trap, and be used to create a single-ion phonon laser. However, the single-ion phonon laser works somewhat differently than an , since the phonon frequency is determined by the single-atom oscillation frequency rather than corresponding to a collective oscillation.

In the new study, scientists J. T. Mendonca from the Instituto Superior Tecnico (IST) in Lisbon, Portugal, and colleagues from the IST and Umea University in Umea, Sweden, have extended the concept of the single-ion phonon laser to the case of a large ensemble of atoms. In doing so, they have shown that an ultra-cold atomic gas can enable collective phonon excitations. In contrast with the single-ion case, here the phonon frequency is determined by the internal oscillations of the atoms in the gas, similar to how the photon frequency in a laser is determined by internal vibrations of the optical cavity.

“Neither coherent electromagnetic waves, nor coherent sound waves are necessarily difficult to generate,” Mendonca told PhysOrg.com. “It depends on the system of consideration, the frequency range, etc. The difficulty that has been addressed in our work is to copy the laser mechanism, but now generating quanta of sound - phonons - rather than quanta of light - photons. We have shown that cold atom systems can be controlled in great detail, enabling emissions of coherent phonons in a manner copying the celebrated laser mechanism.”

In the new method, the gas is confined in a magneto-optical trap. Three physical processes are used to create the phonon laser instability. First, a red-detuned laser beam cools the atomic gas to ultra-cold temperatures. Then, a blue-detuned laser pumps the ultra-cold to create a population inversion, which is also a standard requirement for optical lasers. Finally, the atoms produce a coherent emission of phonons and then decay into a lower kinetic energy state. The scientists note that the resulting acoustic oscillations can then be coupled to the outside world by mechanical or electromagnetic means, where they could be used to provide a source of coherent acoustic radiation.

Regarding the name of a future phonon laser, scientists have previously considered the term “saser” (Sound Amplification by Stimulated Emission of Radiation). But Mendonca and coauthors suggest that “phaser” (where “phonon” is used instead of “sound”) may be more appropriate, since the proposed phonon laser would excite phonons in a way that is very similar to the laser.

“Using the word 'phonon' emphasizes the quantum nature of the process,” Mendonca said. “Saser is certainly an adequate name as well, but we think phaser has a better ring to it.”

A phonon laser could have some useful applications for researchers, although it's likely that more applications are yet to be found. One possible use of a highly coherent beam of ultrasound is that it could allow researchers to greatly improve the imaging resolution in tomography and other imaging techniques.

“It took a while to discover the many applications of the laser - at first it was considered as an invention without a problem to solve,” Mendonca said. “In our work we have been concerned with the basic science issues rather than applications, but hopefully the case of the phaser could be similar to that of the .”

Explore further: Cold Atom Laboratory creates atomic dance

More information: J. T. Mendonca, et al. “A phonon laser in ultra-cold matter.” Europhysics Letters, 91 (2010) 33001. DOI:10.1209/0295-5075/91/33001

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User comments : 25

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rgwalther
4.1 / 5 (7) Sep 07, 2010
This guy 'et al' seems to be involved in a lot of scientific and legal activities.
Modernmystic
2 / 5 (4) Sep 07, 2010
Yes, very exciting for the medical field...however:

We all can read between the lines here and see how easily something like this could be a weapon, especially a non-lethal.

I'm NOT a big fan of non-lethal weapons, I think due to their very nature they tend to be WAY overused...if you don't believe me look at you-tube videos under the subject. If there were more strictly adhered to guidelines by which these weapons were used by law enforcement my opinion would reverse.

As it stands now I think "over tazing" is a real problem that tends to be scoffed at because after all "he could have been shot", "he was ONLY tazed"...uh no.
TheWalrus
5 / 5 (10) Sep 07, 2010
Phonon torpedos away!

-or-

Set phasers on "shrill."

That is all.
Musashi
4.2 / 5 (5) Sep 07, 2010
I think due to their very nature they tend to be WAY overused...


As opposed to guns used by criminals...
zslewis91
4.2 / 5 (5) Sep 07, 2010


Set phasers on "shrill."



SHRILL HAHAHAHA i love it

MaxwellsDemon
5 / 5 (1) Sep 07, 2010
Phasers will bring acoustic levitation out of the lab and into the marketplace. Next best thing to anti-gravity. If you haven't seen acoustic levitation demonstrated, turn off your volume and marvel at this video made by the brilliant Dr. David Deak, working on contract at NASA in the 80's: http://www.youtub...zmB2bI7s
muggins
1 / 5 (1) Sep 07, 2010
This guy 'et al' seems to be involved in a lot of scientific and legal activities.


lol you gotta be joking?
BloodSpill
not rated yet Sep 07, 2010
Is this going to lead to more or less noise pollution?
DamienS
not rated yet Sep 08, 2010
This guy 'et al' seems to be involved in a lot of scientific and legal activities.


lol you gotta be joking?

Yes, that was the whole point!
DamienS
5 / 5 (1) Sep 08, 2010
Phasers will bring acoustic levitation out of the lab and into the marketplace. Next best thing to anti-gravity. If you haven't seen acoustic levitation demonstrated, turn off your volume and marvel at this video made by the brilliant Dr. David Deak, working on contract at NASA in the 80's: http://www.youtub...zmB2bI7s

Very cool indeed, but I think the audio byproduct might be an issue in practical applications (of levitation).
OKilic
not rated yet Sep 08, 2010
We already have devices that can create extremely coherent (both spatial and temporal) acoustic beams. They are called "speakers".
MaxwellsDemon
not rated yet Sep 08, 2010
@DamienS: Maybe. But when phasers come out, the acoustic energy will be confined to a narrow beam, unlike conventional sound sources that broadcast the energy all over the place. But we can take a step beyond that, and consider the fact that lasers don't create practical radiation pressure effects, but phasers will, because acoustic radiation doesn't tend to melt metal and/or human flesh. So instead of standing wave levitation (per the video), we can employ acoustic beam levitation like this: http://www.google...;f=false

With powerful enough phasers, you could lift lights, robots, people, maybe even cars...planes...all with nice reliable solid state transducers. All we need now is a powerful portable energy source.
MaxwellsDemon
5 / 5 (3) Sep 08, 2010
We already have devices that can create extremely coherent (both spatial and temporal) acoustic beams. They are called "speakers".

That's like saying: "Who needs lasers? We already have extremely coherent (both spatial and temporal) photon beams. They're called "flashlights."
Modernmystic
1 / 5 (2) Sep 08, 2010
I think due to their very nature they tend to be WAY overused...


As opposed to guns used by criminals...


I'm usually pretty toned down on these boards, but honestly what the f*** are you talking about? This has absolutely nothing to do with my point whatsoever, and reminds me of a ape grunting and clicking at something it doesn't understand.

So is your "brilliant" philosophical insight that two wrongs make a "right"?

Please tell me there was something more profound you were trying to say than that tired old fallacy.

The vast majority of people these non-lethals are used on are UNARMED. You DO know what unarmed means don't you?
Skeptic_Heretic
2.3 / 5 (3) Sep 08, 2010
The vast majority of people these non-lethals are used on are UNARMED. You DO know what unarmed means don't you?
The vast majority of unarmed people have the potential to injure or kill an officer of the law. I'd prefer they diffuse the situation immediately with a non-lethal than elevate the situation to a point where gun violence is a potential.

Those officers make between 50 and 100 k a year to potentially lose their life in the defense of people and property. I don't mind if they get a little loose with the taser. It sure beats getting a little loose with the sidearm.
Modernmystic
not rated yet Sep 08, 2010
The vast majority of unarmed people have the potential to injure or kill an officer of the law. I'd prefer they diffuse the situation immediately with a non-lethal than elevate the situation to a point where gun violence is a potential.



The problem is that they tend to shoot 80 year old men sitting on their couch or 13 year old girl skateboarders.

Sell the BS to someone who's buying it, I'm not.

Moreover this kind of lose play with non-lethals tends to escalate the general tension between the general populace and law enforcement and tends to erode the already thin line of respect that exists for many people...which in turn makes violent confrontation MORE likely.

Just as a general question to you SH, is it possible in your view that the government CAN make a mistake, or are you like marjon just as blinded by your statist bias as she by her "Randroid" corporatism?

It wouldn't bother me if the officers who did make mistakes were actually held accountable.
Skeptic_Heretic
not rated yet Sep 08, 2010
Just as a general question to you SH, is it possible in your view that the government CAN make a mistake, or are you like marjon just as blinded by your statist bias as she by her "Randroid" corporatism?
Oh yes. The government is composed of people, and we all make mistakes.

The problem comes in when we say that something is an absolute, or is absolutely true or an absolute authority. That is what should be railed against.
Modernmystic
1 / 5 (1) Sep 08, 2010
Have you ever been shot with a taser SH? Don't lie, your "conscience" is watching.

I have been, and had CS gas used on me...and no I've never been arrested all done in "the line of duty". It's not a trivial experience at all. And when I hear these idiotic gorillas in uniform yelling "stop resisting" to someone they're tasing I REALLY get my hackles up, because I know they've been tased before and there is ZERO possibility of "resisting" anything when you have 50k + volts running through you...

It's just too easy for some of these people to use as a FIRST resort instead of a last. Instead of using the skills they had to use before to talk people down, and take their time with people it's just easier to shock the hell out of them.

If I'm the only one that disturbs then so be it, I'll happily wear any moniker anyone places on me for it.
ereneon
not rated yet Sep 08, 2010
I want ultrasound laser acoustic levitating high speed trains! Or at least a feasibility study...
Ravenrant
2.3 / 5 (3) Sep 08, 2010
Those officers make between 50 and 100 k a year to potentially lose their life in the defense of people and property. I don't mind if they get a little loose with the taser. It sure beats getting a little loose with the sidearm.


Their first priority is to protect themselves not us. That's why there are so many shootings of unarmed and innocent people. Cops are cowards. Watch the video of the pizza guy with the bomb around his neck begging for someone to try and disarm it. The cops just hid and waited for it to go off. Every one of them should be fired and jailed for not doing their job or trying to save the guy. They get paid to protect citizens first, not themselves. No one told them the job was safe when they took it.
Skeptic_Heretic
3 / 5 (2) Sep 08, 2010
Have you ever been shot with a taser SH? Don't lie, your "conscience" is watching.
Shot no, tased at point blank, yes.
I have been, and had CS gas used on me...and no I've never been arrested all done in "the line of duty".
Same, however they didn't tase me in boot or any supplimental. What course did they tase you on?
because I know they've been tased before and there is ZERO possibility of "resisting" anything when you have 50k + volts running through you...
Well that's not really true. Many drugs and certain phenotypical characteristics reduce the effectiveness of tasers. For example, rather fat people don't take too much of a jolt.

It's just too easy for some of these people to use as a FIRST resort instead of a last. Instead of using the skills they had to use before to talk people down, and take their time with people it's just easier to shock the hell out of them.
This is, of course, dependant on circumstance.
Ricochet
not rated yet Sep 08, 2010
If I'm the only one that disturbs then so be it, I'll happily wear any moniker anyone places on me for it.


No, I'd say you're not the only one... One of our local radio personalities, Russ Martin, talked about it on his morning show for about 2 days.
Taps
not rated yet Sep 09, 2010
The vast majority of people these non-lethals are used on are UNARMED. You DO know what unarmed means don't you?
The vast majority of unarmed people have the potential to injure or kill an officer of the law. I'd prefer they diffuse the situation immediately with a non-lethal than elevate the situation to a point where gun violence is a potential.

Those officers make between 50 and 100 k a year to potentially lose their life in the defense of people and property. I don't mind if they get a little loose with the taser. It sure beats getting a little loose with the sidearm.


Just so you know, police officers do not have a super dangerous job. It's not even on the top 10 on the most conservative of studies.

http://hubpages.c...ous_Jobs

As noted on the above URL, Law enforcement in ranks 12th.

Watching a 72 elderly woman on youtube get tassed is just one filmed example. http://www.youtub...0tH5VES0 Yeah, WTH?
iWander
4 / 5 (1) Sep 11, 2010
Some applications depending on strength:

1. Wrecking ball (Demolitions)
2. Air pump for scram jet
3. Drill
4. Non-lethal weapon (stun gun, crowd control)
5. Compactors
6. Water pump (sonic piston)
7. Electricity generation (turbine pressure - hydro)
8. Blast testing
9. Heaters (compress gas)
10. Crash barriers (sonic cushion - think Kevlar meets airbag)
11. Car/Aircraft/train crash protection (sonic cushion)

I'm sure there are plenty more potential applications.
htercass
not rated yet Sep 13, 2010
Pretty possible, indeed. The ideia was, at the moment, to envisage an instability mechanism able to produce coherent emission of photons. Nothing else.