Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

A single photon reveals quantum entanglement of 16 million atoms

16.10.2017

Researchers at UNIGE have demonstrated the entanglement between 16 million atoms in a crystal crossed by a single photon, confirming the theory behind the quantum networks of the future

Quantum theory is unequivocal: it predicts that a vast number of atoms can be entangled and intertwined by a very strong quantum relationship even in a macroscopic structure.


This is a partial view of the source producing the single photons that were stored in the quantum memory to produce entanglement between many atoms inside the memory.

Credit: UNIGE

Until now, however, experimental evidence has been mostly lacking, although recent advances have shown the entanglement of 2,900 atoms. Scientists at the University of Geneva (UNIGE), Switzerland, recently reengineered their data processing, demonstrating that 16 million atoms were entangled in a one-centimetre crystal. Find out all about their research in the journal Nature Communications.

The laws of quantum physics allow to emit signals and immediately detect when they are intercepted by a third party. This property is crucial for data protection, especially in the encryption industry, which can now guarantee that customers will be aware of any interception of their messages. These signals also need to be able to travel long distances using some rather special relay devices, known as quantum repeaters: crystals whose atoms are entangled and unified by a very strong quantum relationship.

When a photon penetrates this small crystal block enriched with rare earth atoms and cooled to 270 degrees below zero (barely three degrees above absolute zero), entanglement is created between the billions of atoms it traverses. This is explicitly predicted by the theory, and it is exactly what happens as the crystal fulfils its function and re-emits -- without reading the information it has received -- in the form of a single photon.

Light analysis: the keystone of the research

It is relatively easy to entangle two particles: splitting a photon, for example, generates two entangled photons that have identical properties and behaviours. «But,» explains Florian Fröwis, a researcher in the applied physics group in UNIGE's science faculty, «it's impossible to directly observe the process of entanglement between several million atoms since the mass of data you need to collect and analyse is so huge.» As a result, Fröwis and his colleagues chose a more indirect route, pondering what measurements could be undertaken and which would be the most suitable ones.

They examined the characteristics of light re-emitted by the crystal, as well as analysing its statistical properties and the probabilities, following two major avenues: that the light is re-emitted in a single direction rather than radiating uniformly from the crystal; and that it is made up of a single photon. In this way, the researchers succeeded in showing the entanglement of 16 million atoms when previous observations had a ceiling of a few thousand.

In a parallel work, scientists at University of Calgary, Canada, demonstrated entanglement between many large groups of atoms. «We haven't altered the laws of physics,» points out Mikael Afzelius, a member of Professor Nicolas Gisin's applied physics group. «What has changed is how we handle the flow of data.»

Particle entanglement is a prerequisite for the quantum revolution that is on the horizon, which will also affect the volumes of data circulating on the networks of the future together with the power and operating mode of quantum computers. Everything, in fact, depends on the relationship between two particles at the quantum level -- a relation that is much stronger than the simple correlations proposed by the laws of traditional physics.

Two socks in the quantum world

Although the concept of entanglement can be hard to grasp, it can be illustrated using two socks! Imagine a physicist who always wears two socks of different colours. When you spot a red sock on his right ankle, you also immediately learn something about the left sock: it is not red. There is a correlation, in other words, between the two socks. This is a reasonably prosaic and quite intuitive occurrence; but when we switch to the world of quantum physics, a new type of correlation -- infinitely stronger and more mysterious -- emerges: entanglement. Now, imagine there are two physicists in their own laboratories, with a great distance separating the two. Each scientist has a quantum particle, a photon, for example.

If these two photons are in an entangled state, the physicists will see non-local quantum correlations, which conventional physics is unable to explain. They will find that the polarisation of the photons is always opposite (as with the socks in the above example), and that the photon has no intrinsic polarisation. The polarisation measured for each photon is, therefore, entirely random and fundamentally indeterminated before being measured. What we are dealing with here is an unsystematic phenomenon that occurs simultaneously in two locations that are far apart... and this is the mystery of quantum correlations!

Media Contact

Florian Fröwis
Florian.Froewis@unige.ch
41-223-790-534

 @UNIGEnews

http://www.unige.ch 

Florian Fröwis | EurekAlert!

More articles from Physics and Astronomy:

nachricht UNLV study unlocks clues to how planets form
13.12.2018 | University of Nevada, Las Vegas

nachricht Unprecedented Views of the Birth of Planets
13.12.2018 | Universität Heidelberg

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: An energy-efficient way to stay warm: Sew high-tech heating patches to your clothes

Personal patches could reduce energy waste in buildings, Rutgers-led study says

What if, instead of turning up the thermostat, you could warm up with high-tech, flexible patches sewn into your clothes - while significantly reducing your...

Im Focus: Lethal combination: Drug cocktail turns off the juice to cancer cells

A widely used diabetes medication combined with an antihypertensive drug specifically inhibits tumor growth – this was discovered by researchers from the University of Basel’s Biozentrum two years ago. In a follow-up study, recently published in “Cell Reports”, the scientists report that this drug cocktail induces cancer cell death by switching off their energy supply.

The widely used anti-diabetes drug metformin not only reduces blood sugar but also has an anti-cancer effect. However, the metformin dose commonly used in the...

Im Focus: New Foldable Drone Flies through Narrow Holes in Rescue Missions

A research team from the University of Zurich has developed a new drone that can retract its propeller arms in flight and make itself small to fit through narrow gaps and holes. This is particularly useful when searching for victims of natural disasters.

Inspecting a damaged building after an earthquake or during a fire is exactly the kind of job that human rescuers would like drones to do for them. A flying...

Im Focus: Topological material switched off and on for the first time

Key advance for future topological transistors

Over the last decade, there has been much excitement about the discovery, recognised by the Nobel Prize in Physics only two years ago, that there are two types...

Im Focus: Researchers develop method to transfer entire 2D circuits to any smooth surface

What if a sensor sensing a thing could be part of the thing itself? Rice University engineers believe they have a two-dimensional solution to do just that.

Rice engineers led by materials scientists Pulickel Ajayan and Jun Lou have developed a method to make atom-flat sensors that seamlessly integrate with devices...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

ICTM Conference 2019: Digitization emerges as an engineering trend for turbomachinery construction

12.12.2018 | Event News

New Plastics Economy Investor Forum - Meeting Point for Innovations

10.12.2018 | Event News

EGU 2019 meeting: Media registration now open

06.12.2018 | Event News

 
Latest News

Foxes in the city: citizen science helps researchers to study urban wildlife

14.12.2018 | Ecology, The Environment and Conservation

Magic number colloidal clusters

13.12.2018 | Life Sciences

UNLV study unlocks clues to how planets form

13.12.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>