New particle might make quantum condensation at room temperature possible

Oct 18, 2013
Schematic representation of the system investigated. An array of silver nanorods is covered by a thin layer (grey) of silicon nitride to protect the silver from oxidising, and by a thicker layer of polymer and organic molecules (orange) that emit light. The light field from the nanorods (red tails) couples to the molecules (letters e and h enclosed by an ellipse), thereby forming plasmon-exciton-polaritons (PEPs). By increasing the density of PEPs, the researchers observed their effective cooling, which paves the way towards their quantum condensation. Credit: Fundamental Research on Matter (FOM)

Researchers from FOM Institute AMOLF, Philips Research, and the Autonomous University of Madrid have identified a new type of particle that might make quantum condensation possible at room temperature. The particles, so called PEPs, could be used for fundamental studies on quantum mechanics and applications in lasers and LEDs. The researchers published their results on 18 October in Physical Review Letters.

In quantum condensation (also known as Bose-Einstein condensation) microscopic with different energy levels collapse into a single macroscopic quantum state. In that state, particles can no longer be distinguished. They lose their individuality and so the matter can be considered to be one 'superparticle'.

Quantum condensation was predicted in the 1920s by Bose and Einstein, who theorised that particles will form a condensate at very low temperatures. The first experimental demonstration of the quantum condensate followed in the 1990s, when a gas of atoms was cooled to just a few billionths of a degree above absolute zero (-273°C). The need for such an extremely low temperature is related to the mass of the particles: the heavier the particles, the lower the temperature at which condensation occurs. This motivated an ongoing search for that may condense at higher temperatures than atoms. The eventual goal is to find particles that form a condensate at .

PEPs

The researchers have created a particle that is a potential candidate for fulfilling the quest: the extremely light plasmon-exciton-polariton (PEP). This particle is hybrid between light and . It consists of photons (light particles), plasmons (particles composed of electrons oscillating in metallic nanoparticles) and excitons (charged particles in ).

The researchers made PEPs using an array of metallic nanoparticles coated with molecules that emit light. This system generates PEPs when it is loaded with energy. Through a careful design of the coupling between plasmons, excitons and photons, the researchers created PEPs with a mass a trillion times smaller than the mass of atoms.

Because of their small mass, these PEPs are suitable candidates for quantum condensation even at room temperature. However, due to losses in the system (such as absorption in the metal) PEPs have a short lifespan, which makes keeping them around long enough to condense a challenge.

First steps

The researchers have shown the first steps towards condensation of PEPs, demonstrating that PEPs cool down as their density increases. However, in the current system cooling down is limited by properties of the organic molecules used in the experiments, which lead to a saturation of the PEP density before sets in. The researchers envisage that it should be possible to overcome these challenges in the future.

Applications

To a large extent, PEPs are composed of photons. Therefore, their decay results in the emission of light. This emitted light has unique properties, which could constitute the basis of new optical devices. In view of recent advances from AMOLF and Philips Research towards improving white LEDs with similar systems, the researchers suggest that from a Bose-Einstein condensate might illuminate our living rooms in the future.

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shavera
5 / 5 (2) Oct 18, 2013
nb: these aren't particles in the "fundamental" sense, like nothing is made of PEPs like they're made of quarks and electrons and stuff. The system of these materials arranged in this way has certain "excitations" that behave like other quantum particles.
Egleton
1.4 / 5 (19) Oct 18, 2013
This is definate evidence that we are trading body parts with aliens for advanced technologies.
Bose Einstein condensates are zero entrophy systems. Zero entrophy is a prerequisite for ex-nihilo energy, as witness the conditions of the big bang.
(Big Bang only if we can believe the red shift= distance malarky. Proof by verbal repetition is not proof at all. Evidence is mounting that the Constants are not. There are many ways to get the foundations of our edifice wrong. Question everything.)
Urgelt
1 / 5 (2) Oct 18, 2013
This article has me shaking my head.

For one thing, PEPs are not new particles. They aren't even particles, but a particular type of short-lived interaction between particles and photons.

For another, it's not at all clear that you can form a Bose-Einstein condensate out of these interactions. The article treats it as an engineering problem, as if the theory behind the idea is settled. It isn't settled, as no-one has ever achieved a condensate made out of PEPs at *any* temperature, let alone room temperature.

And yet another: the article says, "Therefore, their decay results in the emission of light. This emitted light has unique properties, which could constitute the basis of new optical devices." Yet the article doesn't mention what those 'unique properties' are or what sort of new optical devices might arise from those properties.

I can't help but conclude that this is an unhelpful, hyperventilating, and credulous article.
LarryD
1 / 5 (8) Oct 18, 2013
Quite! As a layman I'm aware of 'quasi particles' and immediately recognised the three mentioned in the article. However, I don't have the knowledge to understand how a Polariton,
photon mixed with other quasiparticles, a Exciton, bound state of an electron and hole and a Plasmon, plasma excitation are brought together to form a 'new quasi particle'. Since the latter 2 are 'q-particles' anyway why doesn't a Polariton fit the overall description instead of using PEP? Just my ignorance.
I seem to remember reading somewhere that in the latter half of the last decade Magnon condensate was achieved at close to room temp...excuse my lacking memory and knowledge!
TheGhostofOtto1923
1.8 / 5 (5) Oct 19, 2013
yet the article doesn't mention
I can't fathom why someone would think they can draw conclusions such as yours from reading a press release of what must be a very detailed paper about a very involved series of experiments based on very complex science. Why don't you do some research first to try and find the original paper?
EnricM
1.4 / 5 (10) Oct 20, 2013
This is definate evidence [...]


DEFINITE / DEFINITIVE

Never question grammar.