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 Writing and deleting magnets with lasers
19.04.2018 | Helmholtz-Zentrum Dresden-Rossendorf

nachricht Ultrafast electron oscillation and dephasing monitored by attosecond light source
19.04.2018 | Yokohama National University

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: Writing and deleting magnets with lasers

Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...

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...

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

Diamond-like carbon is formed differently to what was believed -- machine learning enables development of new model

19.04.2018 | Materials Sciences

Electromagnetic wizardry: Wireless power transfer enhanced by backward signal

19.04.2018 | Physics and Astronomy

Ultrafast electron oscillation and dephasing monitored by attosecond light source

19.04.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>