Quantum paradox directly observed -- a milestone in quantum mechanics

Mar 04, 2009
Quantum image

In quantum mechanics, a vanguard of physics where science often merges into philosophy, much of our understanding is based on conjecture and probabilities, but a group of researchers in Japan has moved one of the fundamental paradoxes in quantum mechanics into the lab for experimentation and observed some of the 'spooky action of quantum mechanics' directly.

Hardy's Paradox, the axiom that we cannot make inferences about past events that haven't been directly observed while also acknowledging that the very act of observation affects the reality we seek to unearth, poses a conundrum that quantum physicists have sought to overcome for decades. How do you observe quantum mechanics, atomic and sub-atomic systems that are so small-scale they cannot be described in classical terms, when the act of looking at them changes them permanently?

In a journal paper published in the New Journal of Physics, 'Direct observation of Hardy's paradox by joint weak measurement with an entangled photon pair', today, Wednesday, 4 March, authored by Kazuhiro Yokota, Takashi Yamamoto, Masato Koashi and Nobuyuki Imoto from the Graduate School of Engineering Science at Osaka University and the CREST Photonic Quantum Information Project in Kawaguchi City, the research group explains how they used a measurement technique that has an almost imperceptible impact on the experiment which allows the researchers to compile objectively provable results at sub-atomic scales.

The experiment, based on Lucien Hardy's thought experiment, which follows the paths of two photons using interferometers, instruments that can be used to interfere photons together, is believed to throw up contradictory results that do not conform to our classical understanding of reality. Although Hardy's Paradox is rarely refuted, it was only a thought experiment until recently.

Using an entangled pair of photons and an original but complicated method of weak measurement that does not interfere with the path of the photons, a significant step towards harnessing the reality of quantum mechanics has been taken by these researchers in Japan.

As the researchers write, "Unlike Hardy's original argument, our demonstration reveals the paradox by observation, rather than inference. We believe the demonstrated joint weak measurement is useful not only for exploiting fundamental quantum physics, but also for various applications such as quantum metrology and quantum information technology."

More information: Journal paper: www.iop.org/EJ/abstract/1367-2630/11/3/033011/

Source: Institute of Physics

Explore further: New approach to form non-equilibrium structures

add to favorites email to friend print save as pdf

Related Stories

A tree may have the answers to renewable energy

41 minutes ago

Through an energy conversion process that mimics that of a tree, a University of Wisconsin-Madison materials scientist is making strides in renewable energy technologies for producing hydrogen.

Recommended for you

New approach to form non-equilibrium structures

4 hours ago

Although most natural and synthetic processes prefer to settle into equilibrium—a state of unchanging balance without potential or energy—it is within the realm of non-equilibrium conditions where new possibilities lie. ...

Nike krypton laser achieves spot in Guinness World Records

5 hours ago

A set of experiments conducted on the Nike krypton fluoride (KrF) laser at the U.S. Naval Research Laboratory (NRL) nearly five years ago has, at long last, earned the coveted Guinness World Records title for achieving "Highest ...

Chemist develops X-ray vision for quality assurance

10 hours ago

It is seldom sufficient to read the declaration of contents if you need to know precisely what substances a product contains. In fact, to do this you need to be a highly skilled chemist or to have genuine ...

The future of ultrashort laser pulses

10 hours ago

Rapid advances in techniques for the creation of ultra-short laser pulses promise to boost our knowledge of electron motions to an unprecedented level.

IHEP in China has ambitions for Higgs factory

Jul 23, 2014

Who will lay claim to having the world's largest particle smasher?. Could China become the collider capital of the world? Questions tease answers, following a news story in Nature on Tuesday. Proposals for ...

User comments : 13

Adjust slider to filter visible comments by rank

Display comments: newest first

itistoday
4 / 5 (4) Mar 04, 2009
Thanks for the link to the paper at the end of the article, this summary unfortunately isn't very helpful, but that's understandable as it's a hard topic to distill into plain terms.
superhuman
3 / 5 (4) Mar 04, 2009
This is not a "quantum image" but a random photoshop garbage.
Question
1.5 / 5 (6) Mar 04, 2009
It appears to be circular double talk straight from 1984 that proves nothing.
el_gramador
3 / 5 (2) Mar 04, 2009
The image is most likely just that. An image from off the web. However, I can say that I do believe they can observe the reactions they state. After all a workaround was found to observe quantum phenomena a few months back.
nxtr
1 / 5 (4) Mar 04, 2009
I just want to make sure that someone has considered shooting two photons at something from exactly opposite directions. so that the net effect of the collision would be zero, due to the forces directly contradicting each other. I am not a physicist, and hope that this suggestion is not too mundane. It would seem to ne that this would be an efficient way of locating something without disturbing its original position.
benbenny
1 / 5 (1) Mar 05, 2009
Depending on the particle and the medium, it will have different forms of inherent energy such as rotational energy and vibrational energy, and not only kinetic energy which is what you are talking about. When you shoot a photon at a particle you excite it - again depending on the available degrees of freedom. So shooting a pair of photons at a particle from opposite directions will not create a zero affect at all.
out7x
1 / 5 (4) Mar 05, 2009
This article is gibberish. It seems to be about using entangled photons in the classic double slit experiment.
tkjtkj
3 / 5 (6) Mar 05, 2009
This article is a total waste of space. Not one word is included that might let us comprehend what they claim to have observed. No data, nothing except unsubstantiated, unrevealed, undocumented, and, consequently, useless word-salad.
Shame on you, physorg, for publishing this!
superhuman
3 / 5 (2) Mar 05, 2009
I just want to make sure that someone has considered shooting two photons at something from exactly opposite directions. so that the net effect of the collision would be zero, due to the forces directly contradicting each other. I am not a physicist, and hope that this suggestion is not too mundane. It would seem to ne that this would be an efficient way of locating something without disturbing its original position.


Photon cancellation could perhaps be achieved but there are also two other problems with such approach, first photons are in reality formed by oscillations of electric and magnetic fields and for them to exactly cancel the phase of those oscillations has to be opposite for both photons in collision point. The phase depends on original phase and distance so you would have to know where the particle is to adjust distance so that both phases are opposite in location where the collision with the particle takes place.

Besides even if you managed to do it if the photons perfectly canceled out on the particle the particle would not interact with them at all, the photons would just past as through the vacuum and not detect the particle.

To locate something you have to send in a photon and this photon needs to bounce off (scatter) that object, you can then compute where this scattering took place by detecting the scattered photon and comparing it's direction with that of incident photon.

Unfortunately just as the photon is affected by bouncing off so is the particle, it will change it's speed and direction as a result so the information we get only informs us about past particle position or speed.
glaubel
not rated yet Mar 07, 2009
Yes yes, more spooky action and joint weak measurement! I think very interesting article and thanks for the link at the end, on something which is only superficially like particle physics (photons having no rest mass)

KBK
1 / 5 (1) Mar 08, 2009
Ah. Now I finally get it.

Forest for the trees and all that.

Photons are mis-labeled.

They are the reflection of the interactive energy point between forces (infinite amplitude fields from this dimensional egress viewing point-which devolve into interactive vortex at their junctive meeting point-thus frequency and oscillation of structure and their inherent stability and unwillingness to change-they are stressed into stability via the infinite 2-dimensional amplitude fields from the higher dimension), not a particle at all.

Turn the whole thing around - and it will make more sense.

Incidentally, this also explains why..that when the given military groups fired lasers (for distance and measurement calculations) at the given alien craft--that their propulsive fields would fail and the craft would crash.

Meaning..that laser light is merely a differential organization as reflective point off static field conditions that are different elsewhere-ie, outside of the 'light source'.
bluehigh
1 / 5 (1) Mar 08, 2009
Although Hardy's Paradox is rarely refuted ...

Einstein among eminent scientists suggested it arises because QM (esp. the Copenhagen interp.) was an incomplete theory. Besides suggesting that hidden variables are at work, he is famously quoted as suggesting he did not accept this "spooky action at a distance".

EPR is still widely debated and Hardy's Paradox is a nonsenscal maths game. The attributes of entanglement are more likely artifacts of the experiment caused by unknown (hidden) variables.

KBK
1 / 5 (1) Mar 09, 2009
Just remember-Einstein's UFT --WAS-- published.

It was published for three weeks.

It was near immediately --pulled from publication.

Good luck finding it.