Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Improved interface for a quantum internet


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

Physics Synopsis: A Cavity Just for Two

For further information, contact:
Tracy Northup
Institut für Experimentalphysik
Universität Innsbruck
Tel.: +43 512 507-52463

Christian Flatz
Büro für Öffentlichkeitsarbeit
Universität Innsbruck
Tel.: +43 512 507-32022
Mobil: +43 676 872532022

Weitere Informationen: - Quantum Optics and Spectroscopy group - Institut für Experimentalphysik, Universität Innsbruck

Dr. Christian Flatz | Universität Innsbruck

More articles from Physics and Astronomy:

nachricht First results of NSTX-U research operations
26.10.2016 | DOE/Princeton Plasma Physics Laboratory

nachricht Scientists discover particles similar to Majorana fermions
25.10.2016 | Chinese Academy of Sciences Headquarters

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: Etching Microstructures with Lasers

Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.

This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...

Im Focus: Light-driven atomic rotations excite magnetic waves

Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion

Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Greater Range and Longer Lifetime

26.10.2016 | Power and Electrical Engineering

VDI presents International Bionic Award of the Schauenburg Foundation

26.10.2016 | Awards Funding

3-D-printed magnets

26.10.2016 | Power and Electrical Engineering

More VideoLinks >>>