Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Improved interface for a quantum internet

15.01.2015

A quantum network requires efficient interfaces over which information can be transferred from matter to light and back. In the current issue of Physical Review Letters, Innsbruck physicists led by Rainer Blatt and Tracy Northup show how this information transfer can be optimized by taking advantage of a collective quantum phenomenon.

Quantum computers are no longer just a theoretical concept. In recent years, researchers have assembled and successfully tested the building blocks for a future quantum computer in the laboratory.


The experimental apparatus in which the researchers demonstrate a quantum interface.

Photo: IQOQI/Lackner


Two particles are positioned between highly reflective mirrors and entangled with one another by means of a laser.

Graphic: U. Innsbruck

More than a dozen candidate technologies are currently being studied; of these, ion traps are arguably the most advanced. In an ion trap, single atoms can be confined and precisely controlled by means of lasers. This idea was developed by theorists Ignacio Cirac and Peter Zoller, and a team of Innsbruck experimental physicists under Rainer Blatt has been at the forefront of its implementation.

Based at the University of Innsbruck’s Institute for Experimental Physics, the team first demonstrated in 2013 that quantum information stored in a trapped ion can be deterministically mapped onto a photon, that is, a quantum of light. Thus, they were able to construct an interface between quantum processors and optical fiber-based communication channels. Now the physicists have improved this interface, making use of so-called superradiant states.

A reliable interface

“In order to build a quantum network with trapped ions, we need an efficient interface that will allow us to transfer quantum information from ions to photons,” explains Tracy Northup, project leader in Rainer Blatt’s team. “In our interface, we position two ions between two highly reflective mirrors, which form an optical resonator. We entangle the ions with one another and couple both of them to the resonator.”

The collective interaction between the particles and the resonator can now be tuned in order to enhance the creation of single photons. “This is known as a superradiant state,” explains Bernardo Casabone, the article’s first author. In order to demonstrate that the interface is well suited for quantum information processing, the researchers encode a quantum state in the entangled particles and transfer this state onto a single photon.

Because of the superradiant interaction, the photon is generated almost twice as quickly as in their previous experiment. “Thanks to superradiance, the process of information transfer from the particle to the photon essentially becomes more robust,” Casabone emphasizes. As a consequence, the technical requirements for the construction of accurate interfaces may be relaxed.

Read–write capabilities for a quantum memory
In the same experiments on light–matter interactions, the Innsbuck physicists were also able to create so-called subradiant states. Here, the emission of a photon is suppressed rather than enhanced. “These states are also interesting because the stored information becomes invisible to the resonator, and in that sense, it’s protected,” says Northup. As a result, one can imagine that by switching between sub- and superradiant states, quantum information can be stored in ions and retrieved as photons. In a future quantum computer, such addressable read–write operations may be achieved for a quantum register of trapped ions.

The authors are based at the University of Innsbruck and at the Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences. Their research was supported by the Austrian Science Funds (FWF), the European Union, and Tirolean industry.

Publication: Enhanced quantum interface with collective ion-cavity coupling. B. Casabone, K. Friebe, B. Brändstatter, K. Schüppert, R. Blatt, and T. E. Northup. Phys. Rev. Lett. 114, 023602
http://dx.doi.org/10.1103/PhysRevLett.114.023602

Physics Synopsis: A Cavity Just for Two
http://physics.aps.org/synopsis-for/10.1103/PhysRevLett.114.023601

For further information, contact:
Tracy Northup
Institut für Experimentalphysik
Universität Innsbruck
Tel.: +43 512 507-52463
E-Mail: tracy.northup@uibk.ac.at

Christian Flatz
Büro für Öffentlichkeitsarbeit
Universität Innsbruck
Tel.: +43 512 507-32022
Mobil: +43 676 872532022
E-Mail: christian.flatz@uibk.ac.at

Weitere Informationen:

http://quantumoptics.at - Quantum Optics and Spectroscopy group
http://www.uibk.ac.at/exphys/ - Institut für Experimentalphysik, Universität Innsbruck

Dr. Christian Flatz | Universität Innsbruck

More articles from Physics and Astronomy:

nachricht Measured for the first time: Direction of light waves changed by quantum effect
24.05.2017 | Vienna University of Technology

nachricht Physicists discover mechanism behind granular capillary effect
24.05.2017 | University of Cologne

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: A quantum walk of photons

Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.

The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....

Im Focus: Turmoil in sluggish electrons’ existence

An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.

We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...

Im Focus: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.

Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...

Im Focus: World's thinnest hologram paves path to new 3-D world

Nano-hologram paves way for integration of 3-D holography into everyday electronics

An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...

Im Focus: Using graphene to create quantum bits

In the race to produce a quantum computer, a number of projects are seeking a way to create quantum bits -- or qubits -- that are stable, meaning they are not much affected by changes in their environment. This normally needs highly nonlinear non-dissipative elements capable of functioning at very low temperatures.

In pursuit of this goal, researchers at EPFL's Laboratory of Photonics and Quantum Measurements LPQM (STI/SB), have investigated a nonlinear graphene-based...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

AWK Aachen Machine Tool Colloquium 2017: Internet of Production for Agile Enterprises

23.05.2017 | Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

 
Latest News

Physicists discover mechanism behind granular capillary effect

24.05.2017 | Physics and Astronomy

Measured for the first time: Direction of light waves changed by quantum effect

24.05.2017 | Physics and Astronomy

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

VideoLinks
B2B-VideoLinks
More VideoLinks >>>