Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Quantum optics allows us to abandon expensive lasers in spectroscopy

22.11.2017

Lomonosov Moscow State University scientists have invented a new method of spectroscopy

An international research group together with scientists from the MSU have developed a time-resolved spectroscopy method that allows studying fast processes in samples. The new method works by analyzing quantized light transmitted through a sample, without the use of femtosecond lasers and complex detection systems. This design is much cheaper than the one used currently and, moreover, allows you to study a sample without destroying it. The research has been published in the Scientific Reports journal.


Interferometer developed at Moscow State University.

Credit: Elizaveta Melik-Gaikazyan

One of the most common ways of investigating interactions and processes occurring in a substance is based on measuring the time in which a sample responds to external electromagnetic fields affecting it. According to this temporal response, it is possible to judge which connections exist between the components of the substance. As these times are often measured by femtoseconds (10-15 sec), in such experiments it is customary to use femtosecond lasers capable of generating ultrashort pulses.

The problem is that, firstly, femtosecond lasers have high power, and therefore can damage the object under investigation, and secondly, these lasers are expensive. To solve this problem, the researchers have developed a scheme that allows studying samples with single photons and using ordinary lasers for producing them.

The setup consists of the simplest interferometer that makes it possible to accurately measure the interference of light. In the assembled circuit, a nonlinear crystal is located on the laser path. In it, pairs of entangled photons are created and fly off at a certain angle. The phenomenon of quantum entanglement arises in two or more particles, which can be separated by arbitrarily long distances, but continue to "feel" each other, meaning that an attempt to measure the parameters of one particle leads to an instant determination of the state of the other.

"Thanks to this design, we can measure femtosecond times without a femtosecond laser, using single photons," explained the co-author of the article, a graduate student at the Faculty of Physics of Lomonosov Moscow State University, Elizaveta Melik-Gaykazyan.

The test sample is set inside one arm of the interferometer. One photon of the pair passes through it and hit the beam splitter, where it meetsits counterpart that has passed through the second arm. After that, the photons fall on one of two detectors, which react to single photons. That makes it possible to construct a coincidence circuit: if both photons go to the same detector, it is zero coincidence; if they go to different detectors, it is one. At the moment when the delay between the two arms becomes absolutely identical, the effect of quantum interference occurs - coincidence completely disappears, since photons never fall on both detectors simultaneously.

If the sample is set into the photons' path, pattern of the quantum interference starts to change. In this case, the pairs of entangled photons that come to the splitter become less "identical" than in a situation without a sample. Because of this, the photon reception statistics on the two detectors changes, and from the change in this statistics one can judge the nature of the interactions in the substance under study, for example, estimate the transition time from the excited state to the unexcited state.

For her work, Melik-Gaikazyan received support in the framework of the SIPGA scholarship program, established by the Agency for Science, Technology and Research (Republic of Singapore). She has built an experimental setup, measured the interference pattern with and without the test sample, obtained experimental data and analyzed it.

The researchers have tested and verified the developed method on two samples: a Nd:YAG crystal (an aluminum-yttrium garnet with neodymium) and a matrix of dielectric nanoparticles.

"The new method of analyzing unknown substances can be used in chemistry, biology, and materials science," Melik-Gaykazyan said. "In addition, it can be useful when creating a quantum computer, and when trying to understand how to use quantum light in information technology."

Media Contact

Yana Khlyustova
science-release@rector.msu.ru

http://www.msu.ru 

Yana Khlyustova | EurekAlert!

More articles from Physics and Astronomy:

nachricht What happens when we heat the atomic lattice of a magnet all of a sudden?
17.07.2018 | Forschungsverbund Berlin

nachricht Subaru Telescope helps pinpoint origin of ultra-high energy neutrino
16.07.2018 | National Institutes of Natural Sciences

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 evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Microscopic trampoline may help create networks of quantum computers

17.07.2018 | Information Technology

In borophene, boundaries are no barrier

17.07.2018 | Materials Sciences

The role of Sodium for the Enhancement of Solar Cells

17.07.2018 | Power and Electrical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>