Russian physicists restore the entanglement of 'untangled' quantum light

By: John Wallace | laserfocusworld.com | Posted: 13 Oct 2015, 17:16

Professor Alex Lvovsky (left) and PhD student Alexander Ulanov (right) are pictured with their quantum-entanglement setup. (Credit: Russian Quantum Center)

Scientists from the Russian Quantum Center (Moscow, Russia) have developed a method to restore quantum entanglement and have tested this method in an experiment in which they restored the level of quantum correlation between pulses of light in two optical channels. This research significantly broadens the possibilities of quantum communication and quantum cryptography. The work is a step towards building a quantum repeater.

The phenomenon of quantum entanglement (or quantum correlation) plays a particularly important role in secure quantum communication systems. However, entangled states are very fragile, breaking easily during transmission due to noise or optical losses. In addition, the very creation of entanglement is quite a difficult process. Existing equipment is only capable of transferring data at a distance of no more than 100 km. Many research groups are now looking for ways to increase this limited distance.

Recovery after 20-fold optical loss

Alexander Lvovsky’s group in the Quantum Optics Laboratory at the Russian Quantum Center conducted a series of experiments in which they restored the level of quantum correlation between pulses of light after it was almost completely destroyed after passing through a 20-fold optical loss. This corresponds to the level of loss in 65 km of ordinary fiber-optic cable.

A nonlinear optical crystal of periodically poled potassium titanyl phosphate was used as the source of entangled photons. Picosecond pulses of light generated by a titanium:sapphire laser were fired at the crystal. As a result, entangled photon pairs were produced in the crystal and directed into two different optical channels. In one of them, the light was subjected to 20-fold attenuation using darkened glass, causing the level of entanglement to fall almost to zero. Then an amplification procedure was applied, restoring the quantum properties of light in the channel to levels close to those that occurred before the loss.

The procedure is to mix the light pulse in the channel with a single auxiliary photon in a beamsplitter. A single-photon detector is placed at one of the outputs of the beamsplitter. If the detector clicks, this means that the photon has entered the beamsplitter and left. It would seem that the state of the second pulse to enter the beamsplitter (a part of the entangled state) should not change. But, because of paradoxical properties of quantum interference, the state changes in towards the strengthening of its quantum properties.

This phenomenon, discovered by Lvovsky and colleagues in 2002 (doi: 10.1103/PhysRevLett.88.250401), has been named quantum catalysis, because the auxiliary photon, like a chemical catalyst, is not itself involved in the reaction, but changes the state of light in the other channel.

Source: Russian Quantum Center

REFERENCE:

1.  Alexander E. Ulanov et al., Nature Photonics (2015); doi: 10.1038/nphoton.2015.195

Laser

Nonlinear optical crystal changes the color of laser light on the femtosecond time scale

Nonlinear optical crystal changes the color of laser light on the femtosecond time scale

Nonlinear optical crystal changes the color of laser light on the femtosecond time scale.

Diamond lenses make materials-processing laser optics lighter

Diamond lenses make materials-processing laser optics lighter

Diamond lenses make materials-processing laser optics lighter.

IPG Photonics to acquire Innovative Laser Technologies

IPG Photonics to acquire Innovative Laser Technologies

Laser systems maker IPG Photonics has signed an agreement to acquire Innovative Laser Technologies (ILT) for $40 million in cash.

Clemson Receives Funding from DoD for Laser Weaponry Research

Clemson Receives Funding from DoD for Laser Weaponry Research

Two researchers at Clemson University are taking different but complementary approaches to creating a high-energy laser that could be used as a weapon. The engineers are receiving a combined $3.2 million from the U.S. Department of Defense (DoD) to help fund the research.

Power-scalable semiconductor laser is focus of UTA research grant

Power-scalable semiconductor laser is focus of UTA research grant

Conventional high-power lasers are bulky and require equipment that makes them difficult to use in portable platforms, but a University of Texas at Arlington engineer is working to develop a semiconductor laser that addresses these issues.

IPG Photonics acquires volume Bragg gratings maker OptiGrate

IPG Photonics acquires volume Bragg gratings maker OptiGrate

IPG Photonics has acquired OptiGrate, whose volume Bragg grating (VBG)-based components improve performance, miniaturization, and cost reduction of ultrafast lasers for micromachining, medical, and other applications.

Graphene may serve as fast saturable absorber

Graphene may serve as fast saturable absorber

Graphene may serve as fast saturable absorber.

XFEL Generates First Laser Light

XFEL Generates First Laser Light

The European X-ray Free-Electron Laser (XFEL), the largest x-ray laser in the world, has generated its first laser light, reaching the last major milestone before its official opening in September.

Focuslight completes acquisition of micro-optics maker LIMO

Focuslight completes acquisition of micro-optics maker LIMO

High-power laser diode maker Focuslight Technologies has completed its acquisition of LIMO Lissotschenko Mikrooptik (Dortmund, Germany), a supplier of micro-optics and beam shaping systems. The transaction was funded by issuing shares of stock to investors.

University of Strathclyde acquires 350 TW laser from Thales

University of Strathclyde acquires 350 TW laser from Thales

One of the world's most powerful lasers--capable of bursts of light equivalent to twenty times all the power consumed on Earth, captured in fraction of a second--has been acquired by the University of Strathclyde.

LaserBond ships first laser cladding system to China

LaserBond ships first laser cladding system to China

LaserBond has shipped its first customized laser cladding system to China in a AU$1.4 million (US$1.03 million) deal.

Researchers develop automated laser process for cutting sheet piling underwater

Researchers develop automated laser process for cutting sheet piling underwater

Researchers at Laser Zentrum Hannover (LZH), in collaboration with the Institute of Materials Science at the Leibniz University of Hannover (both in Hannover, Germany), is developing a laser-based, automated process for cutting sheet piling underwater.

MicroVision Signs Laser Beam Scanning System Contract

MicroVision Signs Laser Beam Scanning System Contract

Display and sensor developer MicroVision Inc. has signed a contract with a major technology company to develop a laser beam scanning (LBS) display system and produce specific components.

LightFab to introduce selective laser etching to US market

LightFab to introduce selective laser etching to US market

PhotoMachining and LightFab have begun a collaborative effort to promote selective laser etching (SLE) using femtosecond lasers in the US market.

Research team develops visible light-activatable drug to treat pain

Research team develops visible light-activatable drug to treat pain

A team of researchers at the Institute of Neurosciences of the University of Barcelona (Spain) and colleagues has developed a light-activated drug for pain treatment.

Necsel Acquires NGI Assets

Necsel Acquires NGI Assets

Laser developer Necsel IP Inc. has acquired the assets of Nathaniel Group Inc. (NGI), a medical illuminator manufacturer.

Lab-scale laser device prototype discerns between healthy and damaged skin tissue

Lab-scale laser device prototype discerns between healthy and damaged skin tissue

Researchers from the Technical University of Madrid, in collaboration with the Polytechnic University of Valencia and the Centro de Investigación Biomédica en Red's Bioengineering, Biomaterials and Nanomedicine, have designed a laser device specifically designed for optical hyperthermia applications

Waveguide Device Transmits Laser Light Through Direct Contact With Skin

Waveguide Device Transmits Laser Light Through Direct Contact With Skin

A device that transmits laser light into human tissue through direct contact, rather than open-air transmission, could help reduce safety concerns in laser-based dermatological procedures and improve targeted laser transmission through surface layers of the skin.

Changing the Shape of CQDs Could Enable Continuous QD Lasing

Changing the Shape of CQDs Could Enable Continuous QD Lasing

A novel method for fabricating lasers uses saucer-shaped quantum dots (QDs) to produce continuous laser light that could be brighter, less expensive and more tuneable than current devices.

Ultrafast laser-activated gold pyramids could deliver drugs, DNA into cells harmlessly

Ultrafast laser-activated gold pyramids could deliver drugs, DNA into cells harmlessly

Researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences have developed a method that uses gold microstructures to deliver various molecules—such as drugs or DNA—into cells with high efficiency and no lasting damage.

Electrons used to control ultrashort laser pulses

Electrons used to control ultrashort laser pulses

Researchers at Lund University and Louisiana State University have developed a tool that makes it possible to control extreme UV light - light with much shorter wavelengths than visible light. The new method uses strong laser pulses to direct the short bursts of light.

TRUMPF develops high-power ultrafast laser system

TRUMPF develops high-power ultrafast laser system

TRUMPF has joined a recently established research project named ScULPT,with the objective of developing an efficient, powerful, ultrafast laser system to enable micromachining of different types of glass and metals with a tenfold increase in throughput.

Selective Laser Melting Produces Safer Automotive Components

Selective Laser Melting Produces Safer Automotive Components

Using selective laser melting (SLM), engineers are creating lightweight automotive components that boost vehicle fuel efficiency, cut noise and lessen CO2 emissions.

 Ultrafast lasers enable rapid, photo-magnetic optical storage

Ultrafast lasers enable rapid, photo-magnetic optical storage

Andrzej Stupakiewicz from the University of Bialystok in Poland and colleagues used precisely tuned laser pulses to store information on garnet crystal at speeds 1000 times faster than magnetic hard drives with very little heat.

Tiny Laser Created Using Nanoparticles

Tiny Laser Created Using Nanoparticles

Using “dark lattice modes,” researchers at Aalto University have created a plasmonic nanolaser that operates at visible light frequencies.

Panasonic acquires all shares of TeraDiode

Panasonic acquires all shares of TeraDiode

On January 2, 2017, diverse electronics technologies developer Panasonic (Osaka, Japan) signed a contract to acquire all shares of TeraDiode (Wilmington, MA), a global supplier of high-brightness direct diode lasers for industrial use.

Four laser companies to exceed $1 billion revenue in 2016

Four laser companies to exceed $1 billion revenue in 2016

The year is closing and it looks like a good one for most players in laser industry.

Laser irradiation produces vesicle explosions to mimic cellular reactions

Laser irradiation produces vesicle explosions to mimic cellular reactions

A team of researchers from the Centre National De La Recherche Scientifique and the Polytechnic Institute of Bordeaux used laser irradiation to control the explosion of polymersomes.

Nanocrystal can Transform Light to Visible Spectrum

Nanocrystal can Transform Light to Visible Spectrum

A novel nanocrystal, 500 times smaller than a human hair, is capable of changing the intensity, shape and color of light. Developed by researchers at The Australian National University (ANU), the nanocrystal was built on glass so that light could pass through it.

TRUMPF opens technology and laser center in Silicon Valley

TRUMPF opens technology and laser center in Silicon Valley

Laser system manufacturer TRUMPF (Ditzingen, Germany), which supplies laser processing solutions for micromachining applications and coating technology, has opened a new technology and laser center in Santa Clara, CA.

Retrofit Table Laser System

Retrofit Table Laser System

The Micro-LAM Optimus T+1 Laser from Novotech Inc. is a retrofit table system to standard diamond turning machines.

Pulsed Laser Wavelength Meters

The 871 Series of Pulsed Laser Wavelength Meters from Bristol Instruments Inc. can measure accuracies as high as ± 0.2...

High-Power Laser Modules

High-Power Laser Modules

The LCW/SCW series of high-power laser modules from OSI Laser Diode Inc. is designed for optical testing.

QDH20 Optical Encoder

QDH20 Optical Encoder

The QDH20 industrial-grade optical encoder from Quantum Devices Inc. provides an improved feedback solution in applications...