Nanotechnology Now

Our NanoNews Digest Sponsors
Heifer International

Wikipedia Affiliate Button

Home > Press > Research Reveals Exotic Quantum States in Double-Layer Graphene: Findings shed new light on the nature of electron interactions in quantum systems and establish a potential new platform for future quantum computers

A new type quasiparticle is discovered in graphene double-layer structure. This so-called composite fermion consists of one electron and two different types of magnetic flux, illustrated as blue and gold colored arrows in the figure. Composite fermions are capable of forming pairs, such unique interaction lead to experimental discovery of unexpected new quantum Hall phenomena.

Michelle Miller and Jia Li/Brown University
A new type quasiparticle is discovered in graphene double-layer structure. This so-called composite fermion consists of one electron and two different types of magnetic flux, illustrated as blue and gold colored arrows in the figure. Composite fermions are capable of forming pairs, such unique interaction lead to experimental discovery of unexpected new quantum Hall phenomena. Michelle Miller and Jia Li/Brown University

Abstract:
Researchers from Brown and Columbia Universities have demonstrated previously unknown states of matter that arise in double-layer stacks of graphene, a two-dimensional nanomaterial. These new states, known as the fractional quantum Hall effect, arise from the complex interactions of electrons both within and across graphene layers.

Research Reveals Exotic Quantum States in Double-Layer Graphene: Findings shed new light on the nature of electron interactions in quantum systems and establish a potential new platform for future quantum computers

New York, NY | Posted on June 26th, 2019

“The findings show that stacking 2D materials together in close proximity generates entirely new physics,” said Jia Li, assistant professor of physics at Brown, who initiated this work while a post-doc at Columbia working with Cory Dean, professor of physics, and Jim Hone, professor of mechanical engineering. “In terms of materials engineering, this work shows that these layered systems could be viable in creating new types of electronic devices that take advantage of these new quantum Hall states.”



A new type quasiparticle is discovered in graphene double-layer structure. This so-called composite fermion consists of one electron and two different types of magnetic flux, illustrated as blue and gold colored arrows in the figure. Composite fermions are capable of forming pairs, such unique interaction lead to experimental discovery of unexpected new quantum Hall phenomena.

Michelle Miller and Jia Li/Brown University



The research is published in the journal Nature Physics.

Importantly, says Hone, Wang Fong-Jen Professor of Mechanical Engineering at Columbia Engineering, several of these new quantum Hall states “may be useful in making fault-tolerant quantum computers.”

The Hall effect emerges when a magnetic field is applied to a conducting material in a perpendicular direction to a current flow. The magnetic field causes the current to deflect, creating a voltage in the transverse direction, called the Hall voltage. The strength of the Hall voltage increases with the strength of the magnetic field. The quantum version of the Hall effect was first discovered in experiments performed in 1980 at low temperatures and strong magnetic fields. The experiments showed that rather than increasing smoothly with magnetic field strength, the Hall voltage increases in step-wise (or quantized) fashion. These steps are integer multiples of fundamental constants of nature and are entirely independent of the physical makeup of the material used in the experiments. The discovery was awarded the 1985 Nobel Prize in Physics.

A few years later, researchers working at temperatures near absolute zero and with very strong magnetic fields found new types of quantum Hall states in which the quantum steps in Hall voltage correspond to fractional numbers, hence the name fractional quantum Hall effect. The discovery of the fractional quantum Hall effect won another Nobel Prize, in 1998. Theorists later posited that the fractional quantum Hall effect is related to the formation of quasi-particles called composite fermions. In this state, each electron combines with a quantum of magnetic flux to form a composite fermion carrying a fraction of an electron charge giving rise to the fractional values in Hall voltage.

The composite fermion theory has been successful in explaining a myriad of phenomena observed in single quantum well systems. This new research used double-layer graphene to investigate what happens when two quantum wells are brought close together. Theory had suggested that the interaction between two layers would lead to a new type of composite fermion, but this had never been observed in experiment.

For the experiments, the team built on many years of work at Columbia to improve the quality of graphene devices, creating ultra-clean devices entirely from atomically flat 2D materials. The core of the structure consists of two graphene layer separated by a thin layer of hexagonal boron nitride as an insulating barrier. The double-layer structure is encapsulated by hexagonal boron nitride as a protective insulator, and graphite as a conductive gate to change the charge carrier density in the channel.

“Once again the incredible versatility of graphene has allowed us to push the boundaries of device structures beyond what was previously possible.” says Dean, a professor of physics at Columbia University. “The precision and tunability with which we can make these devices is now allowing us to explore an entire realm of physics that was just recently thought to be totally inaccessible.”

The graphene structures were then exposed to strong magnetic fields—millions of times stronger than Earth’s magnetic field. The research produced a range of fractional quantum Hall states, some of which demonstrate excellent agreement with the composite fermion model, and some that had never been predicted or seen.

“Apart from the interlayer composite fermions, we observed other features that cannot be explained within the composite fermion model,” said Qianhui Shi, the paper’s co-first author and postdoctoral researcher at Columbia. "A more careful study revealed that, to our surprise, these new states result from pairing between composite fermions. Pairing interaction between adjacent layers and within the same layer give rise to a variety of new quantum phenomena, making double-layer graphene an exciting platform to study.”

“Of particular interest,” says Hone, “are several new states that have the potential of hosting non-Abelian wave functions—states that don’t quite fit the traditional composite fermion model.” In non-Abelian states, electrons maintain a kind of “memory” of their past positions relative to each other. That has potential in enabling quantum computers that do not require error correction, which is currently a major stumbling block in the field.

“These are the first new candidates for non-Abelian states in 30 years,” Dean said. “It’s really exciting to see new physics emerge from our experiments.”

About the Study

The study is titled “Pairing states of composite fermions in double-layer graphene.”

The authors are: Jia Li, Qianhui Shi, Yihang Zeng, Kenji Watanabe, Takashi Taniguchi, James Hone and Cory Dean.

The study was supported by the National Science Foundation (DMR-1507788), the David and Lucille Packard Foundation, and the Department of Energy (DE-SC0016703).

The magnetic field experiments were done at the National High Magnetic Field Laboratory in Tallahassee, Florida, a nationally funded user facility.

The authors declare no competing interests.

####

For more information, please click here

Contacts:
Holly Evarts, Director of Strategic Communications and Media Relations, Columbia Engineering

212-854-3206 (o), 347-453-7408 (c),

Kevin Stacey, Senior Writer, Physical Sciences, Brown University

401-863-3766 (o); 401-447-3800,

Copyright © Columbia University School of Engineering and Applied Science

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related Links

Paper:

Related News Press

News and information

Nano bulb lights novel path: Rice University engineers create tunable, nanoscale, incandescent light source September 20th, 2019

The future of materials with graphene nanotubes starts in Japan September 19th, 2019

Tiny bubbles in our body could fight cancer better than chemo September 18th, 2019

Keystone Nano Announces FDA Approval of Investigational New Drug Application for Ceraxa for the Treatment of Acute Myeloid Leukemia September 18th, 2019

Graphene/ Graphite

The future of materials with graphene nanotubes starts in Japan September 19th, 2019

New health monitors are flexible, transparent and graphene enabled September 13th, 2019

Quantum Physics

Uncovering the hidden “noise” that can kill qubits: New detection tool could be used to make quantum computers robust against unwanted environmental disturbances September 17th, 2019

A Quantum Leap: $25M grant makes UC Santa Barbara home to the nation’s first NSF-funded Quantum Foundry, a center for development of materials for quantum information-based technologies September 16th, 2019

Scientists couple magnetization to superconductivity for quantum discoveries September 6th, 2019

In a quantum future, which starship destroys the other? Quantum physicists blur the lines of cause and effect, illustrating how a sequence of events can flip and co-exist at the same time August 23rd, 2019

Laboratories

Scientists couple magnetization to superconductivity for quantum discoveries September 6th, 2019

Rice reactor turns greenhouse gas into pure liquid fuel: Lab's 'green' invention reduces carbon dioxide into valuable fuels September 3rd, 2019

Govt.-Legislation/Regulation/Funding/Policy

Nano bulb lights novel path: Rice University engineers create tunable, nanoscale, incandescent light source September 20th, 2019

Tiny bubbles in our body could fight cancer better than chemo September 18th, 2019

Keystone Nano Announces FDA Approval of Investigational New Drug Application for Ceraxa for the Treatment of Acute Myeloid Leukemia September 18th, 2019

A Quantum Leap: $25M grant makes UC Santa Barbara home to the nation’s first NSF-funded Quantum Foundry, a center for development of materials for quantum information-based technologies September 16th, 2019

Possible Futures

Nano bulb lights novel path: Rice University engineers create tunable, nanoscale, incandescent light source September 20th, 2019

The future of materials with graphene nanotubes starts in Japan September 19th, 2019

Tiny bubbles in our body could fight cancer better than chemo September 18th, 2019

Keystone Nano Announces FDA Approval of Investigational New Drug Application for Ceraxa for the Treatment of Acute Myeloid Leukemia September 18th, 2019

Chip Technology

Nano bulb lights novel path: Rice University engineers create tunable, nanoscale, incandescent light source September 20th, 2019

The future of materials with graphene nanotubes starts in Japan September 19th, 2019

Uncovering the hidden “noise” that can kill qubits: New detection tool could be used to make quantum computers robust against unwanted environmental disturbances September 17th, 2019

A Quantum Leap: $25M grant makes UC Santa Barbara home to the nation’s first NSF-funded Quantum Foundry, a center for development of materials for quantum information-based technologies September 16th, 2019

Quantum Computing

Uncovering the hidden “noise” that can kill qubits: New detection tool could be used to make quantum computers robust against unwanted environmental disturbances September 17th, 2019

A Quantum Leap: $25M grant makes UC Santa Barbara home to the nation’s first NSF-funded Quantum Foundry, a center for development of materials for quantum information-based technologies September 16th, 2019

Scientists couple magnetization to superconductivity for quantum discoveries September 6th, 2019

Breakthrough enables storage and release of mechanical waves without energy loss: The development may have broad implications for efficient harvesting, storing, and control of energy flow for mechanical and optical applications August 30th, 2019

Discoveries

Nano bulb lights novel path: Rice University engineers create tunable, nanoscale, incandescent light source September 20th, 2019

Tiny bubbles in our body could fight cancer better than chemo September 18th, 2019

Uncovering the hidden “noise” that can kill qubits: New detection tool could be used to make quantum computers robust against unwanted environmental disturbances September 17th, 2019

Scientists create a nanomaterial that is both twisted and untwisted at the same time: The material developed at University of Bath allows for incredibly sensitive detection of the direction molecules twist September 13th, 2019

Announcements

Nano bulb lights novel path: Rice University engineers create tunable, nanoscale, incandescent light source September 20th, 2019

The future of materials with graphene nanotubes starts in Japan September 19th, 2019

Tiny bubbles in our body could fight cancer better than chemo September 18th, 2019

Keystone Nano Announces FDA Approval of Investigational New Drug Application for Ceraxa for the Treatment of Acute Myeloid Leukemia September 18th, 2019

Interviews/Book Reviews/Essays/Reports/Podcasts/Journals/White papers

Nano bulb lights novel path: Rice University engineers create tunable, nanoscale, incandescent light source September 20th, 2019

Tiny bubbles in our body could fight cancer better than chemo September 18th, 2019

Uncovering the hidden “noise” that can kill qubits: New detection tool could be used to make quantum computers robust against unwanted environmental disturbances September 17th, 2019

Journal Nanotechnology Progress International (JONPI), volume 7, issue 1 out September 16th, 2019

Grants/Sponsored Research/Awards/Scholarships/Gifts/Contests/Honors/Records

One-atom switch supercharges fluorescent dyes: Rice University lab discovers simple technique to make biocompatible 'turn-on' dyes September 13th, 2019

Gem-like nanoparticles of precious metals shine as catalysts: Heated particles shift shape and become highly active catalytically September 12th, 2019

Hard as a diamond? Scientists predict new forms of superhard carbon: A study identifies dozens of new carbon structures that are expected to be superhard, including some that may be about as hard as diamonds September 9th, 2019

A swifter way towards 3D-printed organs: Sacrificial ink-writing technique allows 3D printing of large, vascularized human organ building blocks September 6th, 2019

Quantum nanoscience

Uncovering the hidden “noise” that can kill qubits: New detection tool could be used to make quantum computers robust against unwanted environmental disturbances September 17th, 2019

Scientists couple magnetization to superconductivity for quantum discoveries September 6th, 2019

A graphene superconductor that plays more than one tune: Researchers at Berkeley Lab have developed a tiny toolkit for scientists to study exotic quantum physics July 19th, 2019

Dresden physicists use nanostructures to free photons for highly efficient white OLEDs: Trapped light particles July 12th, 2019

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project