Opposites interfere

July 26, 2007

In a classic physics experiment, photons (light particles), electrons, or any other quantum particles are fired, one at a time, at a sheet with two slits cut in it that sits in front of a recording plate. For photons, a photographic plate reveals an oscillating pattern (bands of light and dark) – a sign that each particle, behaving like a wave, has somehow passed through both slits simultaneously and interfered, canceling the light in some places and enhancing it in others.

If single quantum particles can exist in two places at once, and interfere with themselves in predictable patterns, what happens when there are two quantum particles? Can they interfere with each other?

Prof. Mordehai Heiblum of the Weizmann Institute’s Condensed Matter Physics Department and his research team have been experimenting with electrons fired across special semiconductor devices.

Quantum mechanics predicts that two electrons can indeed cause the same sort of interference as that of a single electron – on one condition: that the two are identical to the point of being indistinguishable. Heiblum and his team showed that, because of such interference, these two particles are entangled – the actions of one are inextricably tied to the actions of the other – even though they come from completely different sources and never interact with each other.

The team’s findings recently appeared in the journal Nature.

Dr. Izhar Neder and Nissim Ofek, together with Dr. Yunchul Chung, Dr. Diana Mahalu and Dr. Vladimir Umansky, fired such identical electron pairs from opposite sides of their device, toward detectors that were placed two to a side of the device.

In other words, each pair of detectors could detect the two particles arriving in one of two ways: particle 1 in detector 1 and particle 2 in detector 2, or, alternatively, particle 2 in detector 1 and particle 1 in detector 2. Since these two 'choices' are indistinguishable, the 'choices' interfere with each other in the same way as the two possible paths of a single quantum particle interfere.

The scientists then investigated how the 'choice' of one particle affected the pathway taken by the other, and found strong correlations between them. These correlations could be affected by changing, for example, the length of the path taken by one particle. This is the first time an oscillating interference pattern between two identical particles has been observed, proving, once again, the success of quantum theory.

Source: Weizmann Institute of Science

Explore further: New method allows for quick, precise measurement of quantum states

Related Stories

Recommended for you

Flexible ferroelectrics bring two material worlds together

January 17, 2017

Until recently, "flexible ferroelectrics" could have been thought of as the same type of oxymoronic phrase. However, thanks to a new discovery by the U.S. Department of Energy's (DOE) Argonne National Laboratory in collaboration ...

First-ever X-ray image capture of material defect process

January 17, 2017

From blacksmiths forging iron to artisans blowing glass, humans have for centuries been changing the properties of materials to build better tools – from iron horseshoes and swords to glass jars and medicine vials.

Theory lends transparency to how glass breaks

January 16, 2017

Over time, when a metallic glass is put under stress, its atoms will shift, slide and ultimately form bands that leave the material more prone to breaking. Rice University scientists have developed new computational methods ...

A novel way to put flame retardant in a lithium ion battery

January 16, 2017

(Phys.org)—A team of researchers at Stanford University has found a novel way to introduce flame retardant into a lithium ion battery to prevent fires from occurring. In their paper published in the journal Science Advances, ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.