Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Dissipation desired

21.07.2009
Novel concept for universal quantum computers exploits dissipative processes.

Classical computers are not powerful enough to describe even simple quantum systems. All the more it is difficult to understand complex many body systems. Quantum computers which use quantum particles instead of classical bits may help to overcome this problem.

Up to now complete isolation of the quantum system from the environment has been considered to be a precondition for the realisation of a universal quantum computer - a high challenge for experimental physics.

A new concept, developed by Prof. Ignacio Cirac, director at Max Planck Institute of Quantum Optics and head of the Theory Division, and two former members of the Theory Division, Dr. Michael Wolf (now at Nils Bohr Institute in Copenhagen), and Prof. Frank Verstraete (now at the University of Vienna) turns these ideas upside down. As the scientists report in Nature Physics (AOP 20 July 2009, DOI 10.1038/NPHYS1342), quantum systems that are coupled to the environment by dissipative processes can be used for efficient universal quantum computation as well as the preparation of exotic quantum states.

Furthermore, these systems exhibit some inherent robustness. Though still being a proof-of-principle demonstration the concept can in principle be verified with systems such as atomic gases in optical lattices or trapped ions.

Standard quantum computation is based on a system of quantum particles such as atoms or ions that serve at storing and encoding information. It exploits the unique property of these particles to take on not only states like '1' or '0' but also all kinds of superposition of these states. Manipulations acting on these qubits are always reversible, dubbed 'unitary'. Standard circuits consist of quantum gates that entangle two qubits at a time. However, this concept faces a strong adversary: once the system starts leaking information to the environment the quantum effects that give rise to the power of computing, cryptography and simulation - superposition and entanglement of states - get destroyed. Therefore the system has to be extremely well isolated from the environment.

On the contrary, the new concept of Cirac, Verstraete and Wolf makes use of these dissipative processes to perform efficient quantum computation and state engineering. In order to do so the dissipation dynamics has to be engineered such that it drives the system towards a steady state. This steady state can then represent the ground state of the system, it could be a particular exotic state, or it could encode the result of the computation. An advantage is the fact that, given the dissipative nature of the process, the system is driven towards its steady state independently of the initial state and hence of eventual perturbation along the way. That's why 'Disspative Quantum Computation' (DQC) exhibits an inherent robustness.

Though neither state preparation nor unitary dynamics are required DQC turns out to obtain a computational power that is equivalent to that of standard quantum circuits. Furthermore, this method is particularly suited for preparing interesting quantum states: for example, topological systems give rise to exotic states that play an important role in novel quantum effects like the fractional quantum Hall-effect.

Right now this concept is a proof-of-principle demonstration that dissipation provides an alternative way of carrying out quantum computations or state engineering. It aims however at being adapted in experiments with systems that use atomic gases in optical lattices or trapped ions. "This way of performing quantum computation defies most of the requirements that were thought to be necessary to build such a device", Prof. Cirac points out. "This may lead to different kinds of realizations of quantum computers that are either most robust or easy to implement. But what is more important, it gives a completely different perspective to the way a quantum computer may work in practice." [Olivia Meyer-Streng]

Original publication:
Frank Verstraete, Michael M.Wolf and J. Ignacio Cirac
Quantum computation and quantum-state engineering driven by dissipation
Nature Physics, Advance Online Publication, 20. Juli 2009, DOI 10.1038/NPHYS1342
Contact:
Prof. Dr. Ignacio Cirac
Professor of Physics, TU München
Max Planck Institute of Quantum Optics
Hans-Kopfermann-Straße 1
85748 Garching
Phone: +49 - 89 / 32905 705 / 736
Fax: +49 - 89 / 32905 336
E-mail: ignacio.cirac@mpq.mpg.de
www.mpq.mpg.de/cirac
Dr. Olivia Meyer-Streng
Press & Public Relations
Max Planck Institute of Quantum Optics
Phone: +49 - 89 / 32905 213
Fax: +49 - 89 / 32905 200
E-mail: olivia.meyer-streng@mpq.mpg.de

Dr. Olivia Meyer-Streng | idw
Further information:
http://www.mpq.mpg.de/cirac

More articles from Physics and Astronomy:

nachricht Heating quantum matter: A novel view on topology
22.08.2017 | Université libre de Bruxelles

nachricht Engineering team images tiny quasicrystals as they form
18.08.2017 | Cornell University

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: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

Molecular volume control

22.08.2017 | Life Sciences

When fish swim in the holodeck

22.08.2017 | Life Sciences

Biochemical 'fingerprints' reveal diabetes progression

22.08.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>