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 December 21, 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 December 21, 2014).

Share This


More From ScienceDaily



More Matter & Energy News

Sunday, December 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Building Google Into Cars

Building Google Into Cars

Reuters - Business Video Online (Dec. 19, 2014) Google's next Android version could become the standard that'll power your vehicle's entertainment and navigation features, Reuters has learned. Fred Katayama reports. Video provided by Reuters
Powered by NewsLook.com
AP Review: Nikon D750 and GoPro Hero 4

AP Review: Nikon D750 and GoPro Hero 4

AP (Dec. 19, 2014) What to buy an experienced photographer or video shooter? There is some strong gear on the market from Nikon and GoPro. The AP's Ron Harris takes a closer look. (Dec. 19) Video provided by AP
Powered by NewsLook.com
Double-Amputee Becomes First To Move Two Prosthetic Arms With His Mind

Double-Amputee Becomes First To Move Two Prosthetic Arms With His Mind

Buzz60 (Dec. 19, 2014) A double-amputee makes history by becoming the first person to wear and operate two prosthetic arms using only his mind. Jen Markham has the story. Video provided by Buzz60
Powered by NewsLook.com
Navy Unveils Robot Fish

Navy Unveils Robot Fish

Reuters - Light News Video Online (Dec. 18, 2014) The U.S. Navy unveils an underwater device that mimics the movement of a fish. Tara Cleary reports. Video provided by Reuters
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