Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Light’s improbable connection mapped

11.10.2013
Ultrafast laser pulses and precisely cut optical crystals could control the quantum properties of light

Quantum optics scientists and engineers are striving to harness the properties of small packets of light called photons to improve communications and computational devices. Vital to these efforts is an invisible connection between pairs of photons; understanding this effect is therefore crucial.

By mapping the connections, researchers at the A*STAR Data Storage Institute, Singapore, and in Russia have shown that the properties of each photon in a pair, which were created in the same time and place, are governed by statistics1. The maps could aid future quantum optics engineering efforts.

Many of the early experiments studying the quantum properties of photons used a process called spontaneous parametric down-conversion (SPDC). In SPDC, a photon striking the front of a slab of a crystalline material with specific nonlinear optical properties decays into two lower-energy photons. These photons, referred to as the signal and the idler, are ‘entangled’ — intimately coupled in a way that classical physics cannot describe.

The properties of the photons are determined not when they leave the back of the slab, but when a measurement is made on one of them. At this moment, the properties of the other photon are immediately determined, even though the two may be separated by a long distance.

The situation is more complicated, however, when short laser pulses are used to control the timing of the process. The SPDC emission from the back of the slab consists of photon pairs, or biphotons, across a broad spectrum of wavelengths. A full understanding of the strength of the connection between any two photons in this complex emission profile is important for optimizing the entangled-photon source, and thus improving optical tests of quantum mechanics.

Dmitry Kalashnikov and co-workers fully plotted the correlations of SPDC-generated photons by carefully tailoring the properties of a nonlinear crystal of â-barium borate and the parameters of the ultrafast laser exciting it. “We fixed the frequency of the signal photon and scanned the frequency of the idler photon to find the maximum correlation between the two,” explains Kalashnikov. “We found that the maximum of the correlation is reached at two distinct frequencies.” This unusual ‘double-peak’ structure occurs only under certain conditions — when the crystal is thick enough (5 millimeters) and the exciting laser pulse length is short (less than 110 femtoseconds).

“The effect is harmful as it decreases the quality of entanglement,” says Kalashnikov. “Scientists and engineers will have to pay attention to this when constructing their quantum optics setups and devices in the future.”

The A*STAR-affiliated researchers contributing to this research are from the Data Storage Institute

Journal information

Kalashnikov, D. A., Fedorov, M. V. & Krivitsky, L. A. Experimental observation of double-peak structure of coincidence spectra in ultrafast spontaneous parametric down-conversion. Physical Review A 87, 013803 (2013)

A*STAR Research | Research asia research news
Further information:
http://www.a-star.edu.sg
http://www.researchsea.com

More articles from Physics and Astronomy:

nachricht UNH scientists help provide first-ever views of elusive energy explosion
16.11.2018 | University of New Hampshire

nachricht NASA keeps watch over space explosions
16.11.2018 | NASA/Goddard Space Flight Center

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: 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...

Im Focus: Research icebreaker Polarstern begins the Antarctic season

What does it look like below the ice shelf of the calved massive iceberg A68?

On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.

Im Focus: Penn engineers develop ultrathin, ultralight 'nanocardboard'

When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure

Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
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

European Space Talks: Weltraumschrott – eine Gefahr für die Gesellschaft?

23.10.2018 | Event News

 
Latest News

Purdue cancer identity technology makes it easier to find a tumor's 'address'

16.11.2018 | Health and Medicine

Good preparation is half the digestion

16.11.2018 | Life Sciences

Microscope measures muscle weakness

16.11.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>