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
1. Alexander E. Ulanov et al., Nature Photonics (2015); doi: 10.1038/nphoton.2015.195
Industrial Lasers Process Fiber Reinforced Plastics
Laser-based technologies that overcome the challenges of processing composite materials — which offer high strength and light weight — hold promise for the automotive and aviation sectors, as well as new applications.
Step towards 'holy grail' of silicon photonics
A group of researchers from the UK, including academics from Cardiff University, has demonstrated the first practical laser that has been grown directly on a silicon substrate.
Acal BFi, Quantum Light Sign Distribution Deal
Advanced electronic supplier Acal BFi Ltd. has signed a pan-European distribution agreement with laser developer Quantum Light Instruments Ltd., covering most of western Europe.
Jena laser system sets another world record
A team of physicists under the leadership of Prof. Dr Malte Kaluza at the Institute of Optics and Quantum Electronics has now improved POLARIS' performance significantly
Ultrafast-laser startup Novae gets 1 million Euros in financing
Novae,a startup company that develops and manufactures ultrafast pulsed lasers for scientific, industrial, and medical applications, has closed a financing round for 1 million Euros through investment Funds including IRDInov, DYNALIM, and Finance Utile.
China Laser Online Expo 2015 Successfully Concluded
China Laser Online Expo 2015 Successfully Concluded.
Pulsed laser ablation improves holographic lens fabrication
Researchers from the University of Birmingham in England and Harvard Medical School and Wellman Center for Photomedicine have developed a one-step rapid holographic recording technique that enables optical structures to be printed on transparent substrates coated with light-absorbing materials.
Renewable NRG Systems to Supply NY State with Doppler Lidar
Windcube 100SRenewable NRG Systems has secured a contract with the state of New York to supply up to 17 Windcube 100S 3D scanning Doppler lidar systems for the Mesonet, an advanced weather network dedicated to improving the detection and prediction of severe weather events.
Laser Welding Improves Temperature Sensors by Peak Sensors
UK-based Peak Sensors has recently invested in the latest laser welding machine from Rofin-Baasel UK. The new installation is intended to further improve temperature sensors made by Peak Sensors.
Metasurface Encodes IR Images
Irregular metasurfaces can be made to encode multiple images at IR frequencies in much the same way as the pixels in a television screen can form a visible-light image.
Optical Resonators Probed with Ion Beams
Ion beams can subtly measure and adjust the performance of microscale optical resonators, a finding that could help refine production of such cavities for applications in sensing and quantum computing.
Laser Measurements Simplify Electronics Testing
Femtosecond lasers may provide a cost-effective alternative to conventional vector network analyzers for high-frequency measurements involved in electronics testing.
Microscopic Laser Printing Method Could Hide Data, Simplify Production
A printing method using nanostructured surfaces and laser pulses has yielded a microscopic image with a resolution of 127,000 dots per inch.
Route des Lasers attracts new firms to French cluster
Startups Moria Lase, Irisiome and Spark Lasers join Aquitaine’s growing photonics and optics group.
The economic impact of additive manufacturing
The economic impact of additive manufacturing could be quite significant.
Cascade laser systems set to ramp, says analyst Tematys
Market set to achieve sales of around $1.7 billion in 2024.
Google patents surgical laser ablation system
Though establishing a patent is only the first step toward the system’s development, the surgical laser could one day be used to fight cancer and indicates an expansion of Google Life Sciences’ (GLS) biomedical interests.
Samsung Ventures invests in Amplitude Laser Group
French maker of ultrafast solid-state lasers to develop solutions for global consumer electronics giant.
Researchers make diamond at room temperature
By using different substrates and changing the duration of the laser pulse, the researchers can also control how quickly the carbon cools.
Femtosecond lasers: Japanese scientists create touchable holograms
Japanese scientists have created technology that can project touchable holograms.
New app allows laser processing simulation
Individual parameters can be adjusted using sliders—the simulation result appears in an adjacent window and changes in real time.
Google patents a system for removing biological tissue with a laser
Google has applied for a patent on a surgical system for removing biological tissue with a laser that delivers electromagnetic radiation.
Leica and NKT Photonics sign supercontinuum laser deal
Laser maker to supply optical device developer with source for specialized FLIM and super resolution imaging and more.
UK creates ￡13M Photonics Manufacturing Hub
The Future Photonics Hub will provide national leadership in manufacturing for next-generation photonics technologies for applications in defense and security, communications, space, semiconductor manufacturing and health care.
New Chinese laser weapon stars on TV
An extreme solution to paparazzi drones.
Stratasys puts 3D printers to work for brain surgery practice
The Israeli tech firm teamed with a medical research facility in Buffalo, New York, to 3D print anatomical models of a patient's entire brain vessel anatomy before she underwent a medical procedure to treat an aneurysm.
Lawrence Livermore has the world's highest peak power laser diodes
The diode arrays, which were developed and fabricated by Lasertel, will act as the primary pump source for the High-Repetition-Rate Advanced Petawatt Laser System (HAPLS), currently under construction at LLNL.
Generating kilotesla magnetic fields with petawatt lasers
A team succeeded in laboratory generation of a magnetic field of 1.5 kilotesla (about 50 million times that of terrestrial magnetism).
Germanium-tin laser for silicon photonics is CMOS compatible
A silicon-based direct-bandgap germanium-tin (GeSn) microdisk laser was reported to emit at a lasing wavelength of 2.5 μm at a power output of 221 kW/cm2.1
Stanford-led team gets $13.5M to develop working laser 'accelerator on a chip' prototype
In the technique, laser light propels electrons through a series of structured glass chips.
Most Popular in News
Surface Mount Semiconductor Laser
Excelitas Technologies Corp. has announced the surface-mount, 905-nm, pulsed semiconductor laser (SMD Laser), offering the...
For applications which do not require the high reflectivity of a dielectric coating, metal mirrors serve as an inexpensive...
Two Component Non-Drip Epoxy Paste
Master Bond EP21NDCL is a unique two component epoxy system that cures optically clear in thin sections, even though Part A...
VI Systems launches 64 Gbps PAM-4
VI Systems GmbH has unveiled a fiber-coupled 850-nm vertical cavity surface emitting laser (VCSEL) transmitter module for...