Featured Research

from universities, journals, and other organizations

New kind of quantum junction

Date:
April 18, 2012
Source:
RIKEN
Summary:
A new type of quantum bit called a "phase-slip qubit" has enabled the world's first-ever experimental demonstration of coherent quantum phase slip. The groundbreaking result sheds light on an elusive phenomenon whose existence -- a natural outcome of the theory of superconductivity -- has long been speculated, but never actually observed.

Energy band gap obtained using energy spectroscopy. Existence of band gap establishes that coherent tunneling has occurred.
Credit: Image courtesy of RIKEN

A new type of quantum bit called a "phase-slip qubit," devised by researchers at the RIKEN Advanced Science Institute and their collaborators, has enabled the world's first-ever experimental demonstration of coherent quantum phase slip (CQPS). The groundbreaking result sheds light on an elusive phenomenon whose existence -- a natural outcome of the hundred-year-old theory of superconductivity -- has long been speculated, but never actually observed.

Related Articles


Superconductivity describes a phenomenon in which electrons pass through certain types of materials without any resistance when cooled below a given temperature. Among the most important applications of superconductivity is the Josephson junction, named after physicist Brian Josephson, who in 1962 predicted that a superconducting current could tunnel between superconductors separated by a thin insulating layer. This phenomenon, the Josephson effect, has been applied in a variety of areas including magnetometer design, voltage standardization, and quantum computing.

Researchers have long known of an intriguing theoretical parallel to the Josephson effect in which insulator and superconductor are reversed: rather than electric charges jumping from one superconducting layer to another across an insulating layer, magnetic flux quanta jump from one insulator to another across a superconducting layer. Quantum tunneling of electrons in the Josephson junction is replaced in this parallel by the coherent "slip" of the phase, a quantum variable that, in superconducting circuits, plays a dual role to that of electric charge.

Coherent quantum phase slip (CQPS), as this phenomenon is known, has long been limited to theory -- but no more. In a paper in Nature, Oleg Astafiev and colleagues at the RIKEN Advanced Science Institute (ASI) and NEC Smart Energy Research Laboratories report on the first direct observation of CQPS in a narrow superconducting wire of indium-oxide (InOx). The wire is inserted into a larger superconducting loop to form a new device called a phase-slip qubit, with the superconducting layer (the thin wire) sandwiched between insulating layers of empty space.

By tuning the magnetic flux penetrating this loop while scanning microwave frequencies, the researchers detected a band gap in the energy curves for the two flux states of the system, just as theory predicts. This gap is a result of quantum mechanics, which prevents the two states from occupying the same energy level, forcing them to tunnel across the superconducting layer -- and through a quantum phase-slip in the narrow wire -- to avoid it. While demonstrating conclusively the existence of CQPS, the successful experiment also ushers in a novel class of devices that exploit the unique functionality of quantum phase-slip to forge a new path in superconducting electronics.


Story Source:

The above story is based on materials provided by RIKEN. Note: Materials may be edited for content and length.


Journal Reference:

  1. O. V. Astafiev, L. B. Ioffe, S. Kafanov, Yu. A. Pashkin, K. Yu. Arutyunov, D. Shahar, O. Cohen, J. S. Tsai. Coherent quantum phase slip. Nature, 2012; 484 (7394): 355 DOI: 10.1038/nature10930

Cite This Page:

RIKEN. "New kind of quantum junction." ScienceDaily. ScienceDaily, 18 April 2012. <www.sciencedaily.com/releases/2012/04/120418134858.htm>.
RIKEN. (2012, April 18). New kind of quantum junction. ScienceDaily. Retrieved October 30, 2014 from www.sciencedaily.com/releases/2012/04/120418134858.htm
RIKEN. "New kind of quantum junction." ScienceDaily. www.sciencedaily.com/releases/2012/04/120418134858.htm (accessed October 30, 2014).

Share This



More Matter & Energy News

Thursday, October 30, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Mind-Controlled Prosthetic Arm Restores Amputee Dexterity

Mind-Controlled Prosthetic Arm Restores Amputee Dexterity

Reuters - Innovations Video Online (Oct. 29, 2014) A Swedish amputee who became the first person to ever receive a brain controlled prosthetic arm is able to manipulate and handle delicate objects with an unprecedented level of dexterity. The device is connected directly to his bone, nerves and muscles, giving him the ability to control it with his thoughts. Matthew Stock reports. Video provided by Reuters
Powered by NewsLook.com
Robots Get Funky on the Dance Floor

Robots Get Funky on the Dance Floor

AP (Oct. 29, 2014) Dancing, spinning and fighting robots are showing off their agility at "Robocomp" in Krakow. (Oct. 29) Video provided by AP
Powered by NewsLook.com
Saharan Solar Project to Power Europe

Saharan Solar Project to Power Europe

Reuters - Business Video Online (Oct. 29, 2014) A solar energy project in the Tunisian Sahara aims to generate enough clean energy by 2018 to power two million European homes. Matt Stock reports. Video provided by Reuters
Powered by NewsLook.com
Lowe's Testing Robot Sales Assistants in California Store

Lowe's Testing Robot Sales Assistants in California Store

Buzz60 (Oct. 29, 2014) Lowe’s is testing out what it’s describing as a robotic shopping assistant in one of its Orchard Supply Hardware Stores in California. Jen Markham explains. Video provided by Buzz60
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

    Environment News

    Technology News



    Save/Print:
    Share:

    Free Subscriptions


    Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

    Get Social & Mobile


    Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

    Have Feedback?


    Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
    Mobile: iPhone Android Web
    Follow: Facebook Twitter Google+
    Subscribe: RSS Feeds Email Newsletters
    Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins