Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Quantum entanglement only dependent upon area

16.09.2013
Two researchers at UCL Computer Science and the University of Gdansk present a new method for determining the amount of entanglement – a quantum phenomenon connecting two remote partners, and crucial for quantum technology - within part of a one-dimensional quantum system.

In their paper, published this week in Nature Physics, Dr Fernando Brandão (UCL Computer Science) and Dr Michał Horodecki (Institute for Theoretical Physics and Astrophysics, University of Gdansk) demonstrate when the correlation between particles in a sample reduces exponentially with distance, the entanglement between one region and the rest of the sample only depends on the area of the boundary between them.

Characterising entangled states is essential for technologies such as quantum computation, quantum communication and quantum cryptography. Entanglement is also the difficulty behind making computer simulations of quantum systems. This finding shows that a large class of quantum systems (those with exponential decay of correlations) has only limited entanglement and so can be simulated easily.

The relationship between area and entanglement was suspected by researchers in this field based on the intuitive argument that if the correlation between particles in a system dropped off rapidly with distance, only nearby particles would be entangled with each other. Therefore, particles far away from a boundary would not participate in entanglement and only the boundary area would be relevant.

However, this tempting idea was undermined by the existence of a counterexample. This seemed to show that even when two regions could be separated by a layer wide enough to cut off nearly all correlation between them, observers would not be able to know as much about each region as they would if they were genuinely isolated. This 'data hiding' phenomenon is a key characteristic of entangled states, where a lack of knowledge of one partner affects what can be measured of the other.

This work resolves the apparent difficulty by combining recent findings from quantum information theory, originally developed for analyzing quantum communication protocols, showing that data hiding cannot hold once exponential decaying correlations are found in all different regions of the system.

Dr Brandão says: "We're very excited to have produced this method. It proves something that seemed to be intuitively true, but the reason why it is true has turned out to be quite different from the original intuition. The result also helps us identify cases where there is low entanglement. These are often good candidates for simulation using classical computers not capable of modeling the consequences of quantum phenomena."

Dr Horodecki says: "What I especially like about our result, is that, perhaps for the first time in this domain, we used solely information-theoretic techniques without assuming any specific physical properties of the system other than exponential decaying correlations. This makes the result very general."

Notes to editors:

The work is published on the Nature Physics website at http://dx.doi.org/10.1038/nphys2747

Contacts:

Dr Fernando Brandao
Lecturer, UCL Computer Science
fgslbrandao@gmail.com
Dr Michał Horodecki
University of Gdansk
fizmh@ug.edu.pl
About UCL (University College London)

Founded in 1826, UCL was the first English university established after Oxford and Cambridge, the first to admit students regardless of race, class, religion or gender and the first to provide systematic teaching of law, architecture and medicine.

We are among the world's top universities, as reflected by our performance in a range of international rankings and tables. According to the Thomson Scientific Citation Index, UCL is the second most highly cited European university and the 15th most highly cited in the world.

UCL has nearly 27,000 students from 150 countries and more than 9,000 employees, of whom one third are from outside the UK. The university is based in Bloomsbury in the heart of London, but also has two international campuses – UCL Australia and UCL Qatar. Our annual income is more than £800 million.

David Weston | EurekAlert!
Further information:
http://www.ucl.ac.uk

More articles from Physics and Astronomy:

nachricht Gamma-ray flashes from plasma filaments
18.04.2018 | Max-Planck-Institut für Kernphysik

nachricht How does a molecule vibrate when you “touch” it?
17.04.2018 | Universität Regensburg

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: Gamma-ray flashes from plasma filaments

Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.

The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...

Im Focus: Basel researchers succeed in cultivating cartilage from stem cells

Stable joint cartilage can be produced from adult stem cells originating from bone marrow. This is made possible by inducing specific molecular processes occurring during embryonic cartilage formation, as researchers from the University and University Hospital of Basel report in the scientific journal PNAS.

Certain mesenchymal stem/stromal cells from the bone marrow of adults are considered extremely promising for skeletal tissue regeneration. These adult stem...

Im Focus: Like a wedge in a hinge

Researchers lay groundwork to tailor drugs for new targets in cancer therapy

In the fight against cancer, scientists are developing new drugs to hit tumor cells at so far unused weak points. Such a “sore spot” is the protein complex...

Im Focus: The Future of Ultrafast Solid-State Physics

In an article that appears in the journal “Review of Modern Physics”, researchers at the Laboratory for Attosecond Physics (LAP) assess the current state of the field of ultrafast physics and consider its implications for future technologies.

Physicists can now control light in both time and space with hitherto unimagined precision. This is particularly true for the ability to generate ultrashort...

Im Focus: Stronger evidence for a weaker Atlantic overturning

The Atlantic overturning – one of Earth’s most important heat transport systems, pumping warm water northwards and cold water southwards – is weaker today than any time before in more than 1000 years. Sea surface temperature data analysis provides new evidence that this major ocean circulation has slowed down by roughly 15 percent since the middle of the 20th century, according to a study published in the highly renowned journal Nature by an international team of scientists. Human-made climate change is a prime suspect for these worrying observations.

“We detected a specific pattern of ocean cooling south of Greenland and unusual warming off the US coast – which is highly characteristic for a slowdown of the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

IWOLIA: A conference bringing together German Industrie 4.0 and French Industrie du Futur

09.04.2018 | Event News

 
Latest News

Improved stability of plastic light-emitting diodes

19.04.2018 | Power and Electrical Engineering

Enduring cold temperatures alters fat cell epigenetics

19.04.2018 | Life Sciences

New capabilities at NSLS-II set to advance materials science

18.04.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>