Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Researchers demonstrated violation of Bell's inequality on frequency-bin entangled photon pairs

08.05.2017

Quantum entanglement, one of the most intriguing features of multi-particle quantum system, has become a fundamental building block in both quantum information processing and quantum computation. If two particles are entangled, no matter how far away they are separated, quantum mechanics predicts that measurement of one particle leads to instantaneous wave-function collapse of the other particle.

Such "spooky action at a distance" seems contradictory to our common belief and, in 1935, Einstein attempted to use entanglement to criticize quantum mechanics -- that the quantum description of physical reality is incomplete.


This is quantum entanglement.

Credit: Physics Department, HKUST

Einstein believed that no information could travel faster than light, and suggested that there might be some local hidden variable theories that could explain the world in a deterministic way, if and only if they obey realism and locality.

In 1964, J. S. Bell showed that the debate can be experimentally resolved by testing an inequality; by measuring correlations between entangled parties, the result calculated from local hidden variable theories should be constrained by the Bell inequality, which on the other hand can be violated in the prediction of quantum mechanics.

Making use of a specifically-developed slow light technique to reduce the velocity of light dramatically, researchers at the Hong Kong University of Science and Technology implemented a Bell Test and were able to generate frequency-bin entangled narrowband biphotons from spontaneous four-wave mixing (SFWM) in cold atoms with a double-path configuration, where the phase difference between the two spatial paths can be controlled independently and nonlocally.

Their findings were published in the journal Optica on April 15, 2017 (doi: 10.1364/OPTICA.4.000388).

"We tested the CHSH Bell inequality and registered |?|=2.52±0.48|S|=2.52±0.48, which violates the Bell inequality |?|?2," said Shengwang Du, professor of Physics at HKUST and the leader of the research team.

"We have unambiguously demonstrated the generation of frequency-bin entangled narrowband (about 1 MHz) biphotons, which can efficiently interact with stationary atomic quantum nodes in an atom-photon quantum network. Because of their narrow bandwidth, these biphotons can be stored and retrieved from a quantum memory with high efficiency."

"Our result, for the first time, tests the Bell inequality in a nonlocal temporal correlation of frequency-bin entangled narrowband biphotons with time-resolved detection," said Xianxin Guo, a co-author of the paper. "This will have applications in quantum information processing involving time-frequency entanglement."

The study revealed the temporal details that agree well with theory calculation based on quantum mechanics, and implies the possibility of encoding and decoding qubit information in the time domain.

"Our narrowband frequency-bin entangled biphoton source in this work can be ideally implemented to produce pure heralded single photons in a two-color qubit state with a tunable phase, making use of entanglement, linear optics, and time-resolved detection," said Guo.

Media Contact

Clare Chan
clarechan@ust.hk
852-235-86306

http://www.ust.hk 

Clare Chan | EurekAlert!

More articles from Physics and Astronomy:

nachricht Exoplanet stepping stones
21.11.2018 | W. M. Keck Observatory

nachricht First diode for magnetic fields
21.11.2018 | Universität Innsbruck

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: First diode for magnetic fields

Innsbruck quantum physicists have constructed a diode for magnetic fields and then tested it in the laboratory. The device, developed by the research groups led by the theorist Oriol Romero-Isart and the experimental physicist Gerhard Kirchmair, could open up a number of new applications.

Electric diodes are essential electronic components that conduct electricity in one direction but prevent conduction in the opposite one. They are found at the...

Im Focus: Nonstop Tranport of Cargo in Nanomachines

Max Planck researchers revel the nano-structure of molecular trains and the reason for smooth transport in cellular antennas.

Moving around, sensing the extracellular environment, and signaling to other cells are important for a cell to function properly. Responsible for those tasks...

Im Focus: UNH scientists help provide first-ever views of elusive energy explosion

Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.

Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...

Im Focus: A Chip with Blood Vessels

Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.

Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...

Im Focus: A Leap Into Quantum Technology

Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.

In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Optical Coherence Tomography: German-Japanese Research Alliance hosted Medical Imaging Conference

19.11.2018 | Event News

“3rd Conference on Laser Polishing – LaP 2018” Attracts International Experts and Users

09.11.2018 | Event News

On the brain’s ability to find the right direction

06.11.2018 | Event News

 
Latest News

Removing toxic mercury from contaminated water

21.11.2018 | Life Sciences

New China and US studies back use of pulse oximeters for assessing blood pressure

21.11.2018 | Medical Engineering

Exoplanet stepping stones

21.11.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>