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 Studying fundamental particles in materials
17.01.2017 | Max-Planck-Institut für Struktur und Dynamik der Materie

nachricht Seeing the quantum future... literally
16.01.2017 | University of Sydney

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: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

Im Focus: How to inflate a hardened concrete shell with a weight of 80 t

At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).

Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...

Im Focus: Bacterial Pac Man molecule snaps at sugar

Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.

The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

Nothing will happen without batteries making it happen!

05.01.2017 | Event News

 
Latest News

Satellite-based Laser Measurement Technology against Climate Change

17.01.2017 | Machine Engineering

Studying fundamental particles in materials

17.01.2017 | Physics and Astronomy

Multiregional brain on a chip

16.01.2017 | Power and Electrical Engineering

VideoLinks
B2B-VideoLinks
More VideoLinks >>>