Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Hidden order found in quantum spin liquid

27.07.2007
An international team, including scientists from the London Centre for Nanotechnology, has detected a hidden magnetic “quantum order” that extends over chains of 100 atoms in a ceramic without classical magnetism. The findings, which are published today (July 26) by Science, have implications for the design of devices and materials for quantum information processing.

In quantum information processing, data is recorded and manipulated as quantum bits or ‘qubits’, generalizations of the classical ‘0’ and ‘1’ bits which are traditionally represented by the ‘on’ and ‘off’ states of conventional switches. It is widely believed that if large-scale quantum computers can be built, they will be able to solve certain problems, such as code breaking, exponentially faster than classical computers.

Theoretically, the spin of an individual electron is an excellent qubit, but in a real material it interacts with other electrons and its useable quantum properties are rapidly lost. The new research is important because it explicitly demonstrates, using a practical material, that a large number of electron spins can be coupled together to yield a quantum mechanical state with no classical analog. In addition, the team has also established the factors that affect the distance over which the hidden ‘quantum order’ can be maintained.

“We had two objectives,” explains Professor Gabriel Aeppli, Director of the London Centre for Nanotechnology and the paper’s senior author. “The first was to show that we could actually image the quantum order, which is sometimes referred to as phase coherence. The second aim was to manipulate the distance over which it can be maintained.” This distance - and how sensitive it is to changes in temperature or chemical impurities in the material - can be essential in determining whether a material will have real-life applications, where it would be crucial to control and maintain quantum order over predetermined extents in space and time.

The team studied a ceramic material consisting of chains of nickel-centered oxygen octahedra laid end-to-end. The chains are not ordinary magnets such as those used to fix reminders onto refrigerator doors, but an exotic quantum spin liquid in which the electron spins (analogous to tiny bar magnets) point in random directions with no particular order, even at very low temperatures.

To measure the quantum order throughout this classically disordered liquid, the scientists used neutrons to image the magnetic excitations - “flips” or fluctuations of the spins - and the distances over which they could propagate. The experiments were performed at the National Institute of Standards and Technology (NIST) Center for Neutron Research in the US and at the ISIS particle accelerator of the Rutherford Appleton Laboratory in the UK.

The scientists found that despite the apparent classical disorder, magnetic excitations could propagate over long chains of atoms at low temperature - in the otherwise magnetically disordered material.

Other examples of large-scale quantum phase coherence include superconductors and superfluids where quantum physics leads to fascinating properties.

The team also discovered that they could limit the coherence or make it disappear altogether by introducing defects into the material either by adding chemical impurities (doping) or heating. These defects break the chains into independent sub-chains, each with its own, hidden order. This part of the reported research is the first step towards engineered spin-based quantum states in ceramics.

Aeppli and other members of the team note that their work was initially not intended to have direct applications, but that they later realized that what they are learning could be applied in a range of fields from nanotechnology to quantum computing.

Collaborators on this research include: Guangyong Xu, of John Hopkins University and Brookhaven National Laboratory; Collin L. Broholm, Ying Chen, and Michel Kenzelmann of Johns Hopkins University and the NIST Center for Neutron Research; Yeong-Ah Soh of Dartmouth College; Gabriel Aeppli of the London Centre for Nanotechnology and University College London; John. F. DiTusa of Louisiana State University; Christopher D. Frost from the ISIS Facility, Rutherford Appleton Laboratory, U.K.; Toshimitsu Ito and Kunihiko Oka of the National Institute of Advanced Industrial Science and Technology (AIST), Japan; and Hidenori Takagi from AIST and University of Tokyo.

The work was funded by the Office of Basic Energy Sciences within the U.S. Department of Energy’s Office of Science, the National Science Foundation, a Wolfson-Royal Society Research Merit Award (UK), and by the Basic Technologies programme of the UK Research Councils.

David Weston | alfa
Further information:
http://www.ucl.ac.uk

More articles from Physics and Astronomy:

nachricht APEX takes a glimpse into the heart of darkness
25.05.2018 | Max-Planck-Institut für Radioastronomie

nachricht First chip-scale broadband optical system that can sense molecules in the mid-IR
24.05.2018 | Columbia University School of Engineering and Applied Science

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: Molecular switch will facilitate the development of pioneering electro-optical devices

A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.

The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...

Im Focus: LZH showcases laser material processing of tomorrow at the LASYS 2018

At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.

At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...

Im Focus: Self-illuminating pixels for a new display generation

There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?

At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

Im Focus: Dozens of binaries from Milky Way's globular clusters could be detectable by LISA

Next-generation gravitational wave detector in space will complement LIGO on Earth

The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

 
Latest News

When corals eat plastics

24.05.2018 | Ecology, The Environment and Conservation

Surgery involving ultrasound energy found to treat high blood pressure

24.05.2018 | Medical Engineering

First chip-scale broadband optical system that can sense molecules in the mid-IR

24.05.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>