Free Newsletters - Space - Defense - Environment - Energy - Solar - Nuclear
..
. 24/7 Space News .




TIME AND SPACE
Scientists Find Way to Maintain Quantum Entanglement in Amplified Signals
by Staff Writers
Moscow, Russia (SPX) Jul 24, 2014


Optical fiber. Normally, transmission of entangled photons through optical fiberruins the entanglement.

Physicists Sergei Filippov (MIPT and Russian Quantum Center at Skolkovo) and Mario Ziman (Masaryk University in Brno, Czech Republic, and the Institute of Physics in Bratislava, Slovakia) have found a way to preserve quantum entanglement of particles passing through an amplifier and, conversely, when transmitting a signal over long distances. Details are provided in an article published in the journal Physical Review A(see preprint).

Quantum entangled particles are considered to be the basis of several promising technologies, including quantum computers and communication channels secured against tapping. Quantum entangled particles are quantum objects that can be described in terms of a common quantum state.

Two quantum entangled particles can be in different places, at any distance from each other, but they still are to be considered as a whole. This effect has no analogues in classical physics, and it has been actively studied for the past few decades.

Physicists have learned to entangle photons and have found application for them, including opticalfiber communication channels which are impossible to tap. When trying to intercept the transmission of data over such a channel, quantum entanglement of photons is inevitably destroyed and the legitimate recipient of the message immediately detects interference.

In addition to this, quantum entanglement allows for carrying out quantum teleportation, wherein a quantum object, for example, an atom, in a certain state in one laboratory transmits its quantum state to another object in another laboratory.

It is quantum entangled particles that play the key role in this process, and it is not necessarily about the quantum entanglement of the atoms between which the transmission of the state takes place.

The latter atom becomes absolutely identical to the former one, which in its turn transfers into a different state during the teleportation. If all atoms of an object were transferred like this, the second laboratory would have its exact copy.

The laws of quantum mechanics do not allow for the teleportation of objects and people, but it is already possible to quantum teleport single photons and atoms, which opens up exciting opportunities for the creation of new computing devices and communication lines.

Due to specific quantum effects, a quantum computer will be able to efficiently solve certain problems, for example, hacking codes used in banking, but for now it is still just a theoretical possibility. In practice, quantum computing and teleportation are obstructed by a process called decoherence.

Decoherence is the destruction of the quantum state due to the interaction of a quantum system with the outside world. For experiments in quantum computing, scientists use single atoms caught in magnetic traps and cooled to temperatures close to absolute zero. After going through kilometers of fiber, photons cease to be quantum entangled in most cases and become ordinary, unrelated light quanta.

To create an effective quantum computing system, scientists have to solve a number of problems, including preserving quantum entanglement when the signal abates and when it passes through an amplifier.

Fiber-optic cables on the ocean bed contain a great deal of special amplifiers composed of optical glass and rare earth elements. It is these amplifiers that make it possible to watch high-resolution videos stored on a server in California from the MIPT campus or a university in Beijing.

In their article, Filippov and Ziman say that a certain class of signals can be transmitted so that the risk ofruining quantum entanglement becomes much lower. In this case, neither the attenuation nor the amplification of a signal ruins the entanglement.

To achieve this effect, it is necessary to have the particles in a special, non-Gaussian state, or, as physicists put it, "the wave function of the particles in the coordinate representation should not be in the form of a Gaussian wave packet."

A wave function is a basic concept of quantum mechanics, and Gaussian distribution is a major mathematical function used not only by physicists but also by statisticians, sociologists and economists.

Quantum mechanics differs from classical mechanics in that there are neither material points, nor clearly specified boundaries for bodies in it. Each object can be described by a wave function - each point in space corresponds to a complex number at each moment.

If this number is squared* one may find an object at a given point. To get information on the momentum, energy, or other physical characteristic, the same wave function has to be exposed to a so-called operator.

* In fact, since the amplitude is expressed as a complex number, it is necessary to multiply the numberby a complex conjugate. This detail was omitted due to reader unfamiliarity with complex numbers.

Link for English version of complex number explanation

Gaussian distribution is a function that in its simplest form (without additional coefficients) looks like e-x2. In diagrams, it appears as a bell curve. Many processes in nature are described via this function when the results of observations are processed using mathematical methods.

Ordinary photons, which are used in most quantum entanglement experiments, are also described by a Gaussian function. The probability of finding a photon at a given point (a translation of the expression "in the coordinate representation") first increases and then decreases according to the rule of the Gaussian bell curve. In this case "it would be impossible to send the entanglement far, even if the signal is very strong," Sergei Filippov told MIPT's press service.

Using photons whose wave function has a different shape should increase the number of entangled photon pairs reaching the destination. However, this does not mean that a signal could be transmitted through a very opaque environment and at very long distances. If the signal/noise ratio falls below a certain critical threshold, quantum entanglement vanishes in any case.

MIPT's press office would like to thank Dr. Sergei Filippov for his invaluable help in writing this article.

.


Related Links
Moscow Institute of Physics and Technology
Understanding Time and Space






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News





TIME AND SPACE
Is The Universe A Bubble? Let's Check
Waterloo, Canada (SPX) Jul 23, 2014
Never mind the big bang; in the beginning was the vacuum. The vacuum simmered with energy (variously called dark energy, vacuum energy, the inflation field, or the Higgs field). Like water in a pot, this high energy began to evaporate - bubbles formed. Each bubble contained another vacuum, whose energy was lower, but still not nothing. This energy drove the bubbles to expand. Inevitably, s ... read more


TIME AND SPACE
China's biggest moon challenge: returning to earth

Lunar Pits Could Shelter Astronauts, Reveal Details of How 'Man in the Moon' Formed

Manned mission to Moon scheduled by Roscosmos for 2020-2031

Landsat Looks to the Moon

TIME AND SPACE
India could return to Mars as early as 2017

Curiosity's images show Earth-like soils on Mars

NASA Seeks Proposals for Commercial Mars Data Relay Satellites

Emirates paves way for Middle East space program with mission to Mars

TIME AND SPACE
Voyager Spacecraft Might Not Have Reached Interstellar Space

New Fort Knox: A means to a solar-system-wide economy

Sierra Nevada Completes Major Dream Chaser NASA CCiCap Milestone

NASA Partners Punctuate Summer with Spacecraft Development Advances

TIME AND SPACE
Lunar rock collisions behind Yutu damage

China to launch HD observation satellite this year

China's Fast Track To Circumlunar Mission

Chinese moon rover designer shooting for Mars

TIME AND SPACE
Next ISS Cargo Spacecraft Rolls Out to Pad

Russian cargo craft docks with ISS, science satellite fails

Russian Cargo Craft Launches for 6-Hour Trek to ISS

ATV-5: loaded and locked

TIME AND SPACE
SpaceX Soft Lands Falcon 9 Rocket First Stage

China to launch satellite for Venezuela

SpaceX Falcon 9 v1.1 Flights Deemed Successful

ISS 'space truck' launch postponed: Arianespace

TIME AND SPACE
'Challenges' in quest to find water on Earth-like worlds: study

Transiting Exoplanet with Longest Known Year

Brown Dwarfs May Wreak Havoc on Orbits of Nearby Planets

NASA Mission To Reap Bonanza of Earth-sized Planets

TIME AND SPACE
New material puts a twist in light

Efficient structures help build a sustainable future

Future Electronics May Depend on Lasers, Not Quartz

USAF orders ground approach radar for Saudi Arabia




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.