Imaging Quantum Entanglement

September 21, 2007
Diagnosing Entanglement Using Neutrons
For simplicity, the team focused on a square of spins, the tiny bar magnets associated with the electrons in the copper atoms in the organometallic material studied by the researchers. The left (c) shows a calculated neutron image for these spins when they behave as classical objects (a), while the right (d) shows the image when they are entangled (b). The images are dramatically different in the two cases, taking the form of a nearly circular spot for the classical case and a cross for the quantum, entangled state. Credit: London Centre for Nanotechnology

An international team including scientists from the London Centre for Nanotechnology (LCN) today publishes findings in the journal Proceedings of the National Academy of Sciences demonstrating the dramatic effects of quantum mechanics in a simple magnet. The importance of the work lies in establishing how a conventional tool of material science – neutron beams produced at particle accelerators and nuclear reactors – can be used to produce images of the ghostly entangled states of the quantum world.

At the nano scale, magnetism arises from atoms behaving like little magnets called ‘spins’. In ferromagnets – the kind that stick to fridge doors – all of these atomic magnets point in the same direction. In antiferromagnets, the spins were thought to spontaneously align themselves opposite to the adjacent spins, leaving the material magnetically neutral overall.

The new research shows that this picture is not correct because it ignores the uncertainties of quantum mechanics. In particular, at odds with everyday intuition, the quantum-mechanical physical laws which operate on the nano-scale allow a spin to simultaneously point both up and down. At the same time, two spins can be linked such that even though it is impossible to know the direction of either by itself, they will always point in opposite directions – in which case they are ‘entangled’.

With their discovery, the researchers demonstrate that neutrons can detect entanglement, the key resource for quantum computing.

One of the lead authors of the work, Professor Des McMorrow from the LCN, comments: “When we embarked on this work, I think it is fair to say that none of us were expecting to see such gigantic effects produced by quantum entanglement in the material we were studying. We were following a hunch that this material might yield something important and we had the good sense to pursue it.”

The researchers’ next steps will be to pursue the implications for high temperature superconductors, materials carrying electrical currents with no heating and which bear remarkable similarities to the insulating antiferromagnets they have studied, and the design of quantum computers.

Source: University College London

Explore further: Is Hawking any closer to solving the puzzle of black holes?

Related Stories

Team claims to have created a sample of stanene

August 5, 2015

(Phys.org)—A team of researchers with members from Stanford University and several institutions in China is claiming to have found a way to create a sample of stanene—a one-atom thick mesh (buckled honeycomb) of tin that ...

Unusual magnetic behavior observed at a material interface

August 18, 2015

An exotic kind of magnetic behavior, driven by the mere proximity of two materials, has been analyzed by a team of researchers at MIT and elsewhere using a technique called spin-polarized neutron reflectometry. They say the ...

Caltech announces discovery in fundamental physics

August 10, 2015

When the transistor was invented in 1947 at Bell Labs, few could have foreseen the future impact of the device. This fundamental development in science and engineering was critical to the invention of handheld radios, led ...

Recommended for you

Seeing quantum motion

August 28, 2015

Consider the pendulum of a grandfather clock. If you forget to wind it, you will eventually find the pendulum at rest, unmoving. However, this simple observation is only valid at the level of classical physics—the laws ...

A little light interaction leaves quantum physicists beaming

August 24, 2015

A team of physicists at the University of Toronto (U of T) have taken a step toward making the essential building block of quantum computers out of pure light. Their advance, described in a paper published this week in Nature ...

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.