Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Russian physicists create a high-precision 'quantum ruler'

24.06.2016

Physicists have devised a method for creating a special quantum entangled state

Physicists from the Russian Quantum Center (RQC), MIPT, the Lebedev Physical Institute, and L'Institut d'Optique (Palaiseau, France) have devised a method for creating a special quantum entangled state. This state enables producing a high-precision ruler capable of measuring large distances to an accuracy of billionths of a metre. The results of the study have been published in Nature Communications.


Alexander Ulanov is in the Laboratory of Quantum Optics, Russian Quantum Center.

Credit: Russian Quantum Center

"This technique will enable us to use quantum effects to increase the accuracy of measuring the distance between observers that are separated from one another by a medium with losses. In this type of medium, quantum features of light are easily destroyed," says Alexander Lvovsky, a co-author of the paper, the head of the RQC scientific team that conducted the research, and a professor of the University of Calgary.

The study focused on what is known as N00N states of photons in which there is a superposition of spatial positions of not one, but several photons. That is, a multiphoton laser pulse is at two points at the same time.

These states could be important for metrology, or, more precisely, they could significantly improve the capabilities of optical interferometers, such as those used to detect gravitational waves in the LIGO project.

In optical interferometers, laser beams from two mirrors "mix" with each other and interference occurs - the light waves either strengthen or cancel each other - depending on the exact position of the mirrors. This allows their microscopic displacements to be measured, because the distance between the interferometric fringes is the same as the wavelength - approximately 0.5-1 microns. However, many experiments require even greater precision. Detecting gravitational waves, for example, required measurements of displacements comparable to the diameter of a proton.

"Though such extremely high sensitivities have already be achieved, N00N states could be useful to increase the accuracy even further, because the interference fringes they create are much narrower than the wavelength." - says Philippe Grangier, another co-author of the study, a professor of L'Institut d'Optique.

"The problem is that N00N states are extremely susceptible to losses. When travelling over long distances -in either atmospheric or fiber channels - a light beam inevitably loses intensity. For ordinary, classical light, that does not matter too much. But if an entangled state of light passes through a medium with even small losses, it "disentangles" and is no longer useful," says Lvovsky.

He and his colleagues found a way of solving this problem.

"There is a phenomenon called entanglement swapping. Suppose that Alice and Bob have an entangled state. If I then take one part of Alice's entangled state, and another part from Bob, and I do a joint measurement on them, the remaining parts of Alice's and Bob's states will also become entangled even though they never interacted" says Lvovsky.

"In our experiment conducted at the RQC laboratory, Alice and Bob create two entangled states. The send one of the parts to a medium with losses, which in our experiment is simulated by darkened glass. A third observer, midway between Alice and Bob, conducts joint measurements on these parts. This results in entanglement swapping: the remaining parts of Alice and Bob's states are in the N00N state. And as these parts did not experience losses, they exhibit their quantum properties in full," explains the lead author of the paper, Alexander Ulanov, a researcher at RQC and MIPT postgraduate student.

According to him, the level of losses in the glass corresponds to an atmospheric thickness of approximately 50 kilometres. The same method could also be used for light propagating in vacuum, either in the current ground-based interferometers such as LIGO, or in future space-based ones such as LISA.

Media Contact

Sergey Divakov
divakov@phystech.edu
7-925-834-0978

 @phystech

https://mipt.ru/english/ 

Sergey Divakov | EurekAlert!

More articles from Physics and Astronomy:

nachricht Further Improvement of Qubit Lifetime for Quantum Computers
09.12.2016 | Forschungszentrum Jülich

nachricht Electron highway inside crystal
09.12.2016 | Julius-Maximilians-Universität Würzburg

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: Electron highway inside crystal

Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.

Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Researchers identify potentially druggable mutant p53 proteins that promote cancer growth

09.12.2016 | Life Sciences

Scientists produce a new roadmap for guiding development & conservation in the Amazon

09.12.2016 | Ecology, The Environment and Conservation

Satellites, airport visibility readings shed light on troops' exposure to air pollution

09.12.2016 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>