Quantum optics breakthrough: New method generates photon triplets

Jul 29, 2010

(PhysOrg.com) -- A significant breakthrough spearheaded by University of Queensland, Canadian and Austrian researchers is featured in the latest issue of the journal Nature.

The breakthrough was made by Thomas Jennewein, Hannes Hübel, Deny Hamel and Kevin Resch of the University of Waterloo, Canada, along with Alessandro Fedrizzi of the University of Queensland, Australia and Sven Ramelow of the Austrian Academy of Sciences.

The international research team achieved a longstanding milestone in quantum optics research — the direct generation of photon triplets. This result has been sought for years but never achieved until now.

“This is going to open a new frontier of quantum optics and allow a new class of experiments in using photons,” lead investigator Associate Professor Thomas Jennewein said.

In the past, the generation of pairs of photons (particles of light) revolutionized and made possible emerging technologies such as and quantum computing with photons.

Typically, these photon pairs were created from strong lasers sent through a crystal — a process known as “parametric down-conversion.”

In the new approach, researchers created photon triplets by producing a first pair of photons using an optical crystal, then splitting one of the photon pairs further into two additional photons inside a second crystal.

It’s a process that was first conceived 20 years ago, but had never before been experimentally observed.

Because each triplet originates from a single pump photon, the quantum correlations will extend over all three in a manner not achievable when using independently created photon pairs.

It is expected that this photon-triplet source will allow tests of novel quantum correlations, and will greatly advance photonic quantum computing.

“It shows the value of a very strong team and a great environment for allowing breakthroughs to happen,”Dr Jennewein said.

In their publication, titled “Direct generation of photon triplets using cascaded photon-pair sources,” the researchers explain that these tripartite will significantly advance quantum information research.

Explore further: Symphony of nanoplasmonic and optical resonators produces laser-like light emission

More information: Hübel H. et al. Nature 466, 601-603 (2010). www.nature.com/nature/journal/… abs/nature09175.html

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danman5000
4 / 5 (2) Jul 29, 2010
Are they talking about three-particle entanglement? If so, how would this work with "binary" properties like spin? i.e. for two particles, if you measure one particle as spin up, you know the other must be spin down so it balances to zero. How would that work with three particles?
Branden520
not rated yet Jul 29, 2010
0 1 2 ? If the 2 was a set probability and 0 and 1 were the same as they are today, wouldn't this allow for actual cognizant AI development? The ability to evaluate a situation and get a probability of failure or success would allow for decisions to be based off of the desired result. I would hate to program this though. I'll leave that to the physics / computer science majors.
Jigga
1 / 5 (5) Jul 29, 2010
How would that work with three particles?
The Pauli's exclusion principle is valid for electrons - not photons, which obey the Bose-Einstein statistics and have no quantum numbers defined.
PinkElephant
3 / 5 (3) Jul 29, 2010
Are they talking about three-particle entanglement? If so, how would this work with "binary" properties like spin? i.e. for two particles, if you measure one particle as spin up, you know the other must be spin down so it balances to zero. How would that work with three particles?
Photons are bosons; they have no spin. The only properties they have are phase, frequency, direction of propagation, and polarization. In this case, the photon triplet isn't entangled: the 3 photons are literally duplicates (clones) of each other, in all respects with the possible exception of propagation vector.
El_Nose
not rated yet Jul 30, 2010
@Branden520

wouldn't this allow for actual cognizant AI development? The ability to evaluate a situation and get a probability of failure or success would allow for decisions to be based off of the desired result.


Short answer: no.

systems you are describing already exist. There are computer programs out there that factor in uncertaintiy in very novel ways- such as voting on decisions between 5 programs all evaulating the same data. They each come to a decision and then a poll is taken and the super majority wins, if only the simple majority reach the conclusion it is assumed one of them made a mistake and they evaluate the data again.

and in creating a cognizant AI -- no because you are thinking about creating sentience and that is now considered an engineering issue due to parallelism. we suspect that sentience might necesitate data being communicated between thousands of connections near simulatneaously.