Nanotechnology Now

Our NanoNews Digest Sponsors
Heifer International

Wikipedia Affiliate Button

Home > Press > A Novel Graphene Quantum Dot Structure Takes the Cake

Scanning tunneling spectroscopy image shows that magnetically confined electrons are arranged in a wedding cake-like structure of energy levels, known as Landau levels, labeled as ll (top panel). Electrons confined to those levels create a series of insulating and conducting rings within graphene (bottom panel).

Credit: NIST
Scanning tunneling spectroscopy image shows that magnetically confined electrons are arranged in a wedding cake-like structure of energy levels, known as Landau levels, labeled as ll (top panel). Electrons confined to those levels create a series of insulating and conducting rings within graphene (bottom panel). Credit: NIST

Abstract:
In a marriage of quantum science and solid-state physics, researchers at the National Institute of Standards and Technology (NIST) have used magnetic fields to confine groups of electrons to a series of concentric rings within graphene, a single layer of tightly packed carbon atoms.

A Novel Graphene Quantum Dot Structure Takes the Cake

Gaithersburg, MD | Posted on August 24th, 2018

This tiered “wedding cake,” which appears in images that show the energy level structure of the electrons, experimentally confirms how electrons interact in a tightly confined space according to long-untested rules of quantum mechanics. The findings could also have practical applications in quantum computing.

Graphene is a highly promising material for new electronic devices because of its mechanical strength, its excellent ability to conduct electricity and its ultrathin, essentially two-dimensional structure. For these reasons, scientists welcome any new insights on this wonder material.

The researchers, who report their findings in the Aug. 24 issue of Science, began their experiment by creating quantum dots—tiny islands that act as artificial atoms—in graphene devices cooled to just a few degrees above absolute zero.

Electrons orbit quantum dots in a way that’s very similar to how they orbit atoms. Like rungs on a ladder, they can only occupy specific energy levels according to the rules of quantum theory. But something special happened when the researchers applied a magnetic field, which further confined the electrons orbiting the quantum dot. When the applied field reached a strength of about 1 Tesla (some 100 times the typical strength of a small bar magnet), the electrons packed closer together and interacted more strongly.

As a result, the electrons rearranged themselves into a novel pattern: an alternating series of conducting and insulating concentric rings on the surface. When the researchers stacked images of the concentric rings recorded at different electron energy levels, the resulting picture resembled a wedding cake, with electron energy as the vertical dimension.

A scanning tunneling microscope, which images surfaces with atomic-scale resolution by recording the flow of electrons between different regions of the sample and the ultrasharp tip of the microscope’s stylus, revealed the structure.

“This is a textbook example of a problem—determining what the combined effect of spatial and magnetic confinement of electrons looks like—that you solve on paper when you’re first exposed to quantum mechanics, but that no one’s actually seen before,” said NIST scientist and co-author Joseph Stroscio. “The key is that graphene is a truly two-dimensional material with an exposed sea of electrons at the surface,” he added. “In previous experiments using other materials, quantum dots were buried at material interfaces so no one had been able to look inside them and see how the energy levels change when a magnetic field was applied.”

Graphene quantum dots have been proposed as fundamental components of some quantum computers.

“Since we see this behavior begin at moderate fields of just about 1 Tesla, it means that these electron-electron interactions will have to be carefully accounted for when considering certain types of graphene quantum dots for quantum computation,” said study co-author Christopher Gutiérrez, now at the University of British Columbia in Vancouver, who performed the experimental work at NIST with co-authors Fereshte Ghahari and Daniel Walkup of NIST and the University of Maryland.

This achievement also opens possibilities for graphene to act as what the researchers call a “relativistic quantum simulator.” The theory of relativity describes how objects behave when moving at or close to light speed. And electrons in graphene possess an unusual property—they move as if they are massless, like particles of light. Although electrons in graphene actually travel far slower than the speed of light, their light-like massless behavior has earned them the moniker of “relativistic” matter. The new study opens the door to creating a table-top experiment to study strongly confined relativistic matter.

Collaborators on this work included researchers from the Massachusetts Institute of Technology, Harvard University, the University of Maryland NanoCenter and the National Institute for Material Science in Ibaraki, Japan.

The measurements suggest that scientists may soon find even more exotic structures produced by the interactions of electrons confined to solid-state materials at low temperatures.

####

For more information, please click here

Contacts:
Ben P. Stein

(301) 975-2763

Copyright © National Institute of Standards and Technology (NIST)

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: Christopher Gutiérrez, Daniel Walkup, Fereshte Ghahari, Cyprian Lewandowski, Joaquin F. Rodriguez-Nieva, Kenji Watanabe, Takashi Taniguchi, Leonid S. Levitov, Nikolai B. Zhitenev and Joseph A. Stroscio. Interaction Driven Quantum Hall Wedding cake-like Structures in Graphene Quantum Dots. Science. Published August 24, 2018. DOI: 10.1126/science.aar2014:

Related News Press

News and information

uSEE breakthrough unlocks the nanoscale world on standard biology lab equipment August 16th, 2019

Optofluidic chip with nanopore 'smart gate' developed for single molecule analysis: Programmable device enables on-demand delivery of individual biomolecules with feedback-controlled gating for high-throughput analysis August 16th, 2019

ULVAC Launches Revolutionary PZT Piezoelectric Thin-film Process Technology and HVM Solution for MEMS Sensors/Actuators: Enabling Reliable, High-quality Film Production for Next Generation Devices August 16th, 2019

RIT to upgrade Semiconductor and Microsystems Fabrication Laboratory through $1 million state grant: Upgrades to clean room will enhance university’s research capabilities in photonics, quantum technologies and smart systems August 16th, 2019

Kavli Lectures: Innovation by evolution and harnessing the quantum mechanics of the hydrogen bond August 15th, 2019

Laboratories

Probing the Origin of Alzheimer’s . . . with Transistors: Novel high-sensitivity detector could aid in early diagnosis August 15th, 2019

Sharp meets flat in tunable 2D material: Rice's new atom-flat compounds show promise for optoelectronics, advanced computing August 12th, 2019

Caught in the act: Images capture molecular motions in real time July 15th, 2019

The best of both worlds: how to solve real problems on modern quantum computers July 12th, 2019

2 Dimensional Materials

You're not so tough, h-BN: Rice University chemists find new path to make strong 2D material better for applications August 14th, 2019

Sharp meets flat in tunable 2D material: Rice's new atom-flat compounds show promise for optoelectronics, advanced computing August 12th, 2019

Graphene/ Graphite

You're not so tough, h-BN: Rice University chemists find new path to make strong 2D material better for applications August 14th, 2019

A modified device fabrication process achieves enhanced spin transport in graphene August 6th, 2019

Quantum Physics

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

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 June 26th, 2019

Govt.-Legislation/Regulation/Funding/Policy

uSEE breakthrough unlocks the nanoscale world on standard biology lab equipment August 16th, 2019

Optofluidic chip with nanopore 'smart gate' developed for single molecule analysis: Programmable device enables on-demand delivery of individual biomolecules with feedback-controlled gating for high-throughput analysis August 16th, 2019

Damaged hearts rewired with nanotube fibers: Texas Heart doctors confirm Rice-made, conductive carbon threads are electrical bridges August 14th, 2019

You're not so tough, h-BN: Rice University chemists find new path to make strong 2D material better for applications August 14th, 2019

Possible Futures

uSEE breakthrough unlocks the nanoscale world on standard biology lab equipment August 16th, 2019

ULVAC Launches Revolutionary PZT Piezoelectric Thin-film Process Technology and HVM Solution for MEMS Sensors/Actuators: Enabling Reliable, High-quality Film Production for Next Generation Devices August 16th, 2019

RIT to upgrade Semiconductor and Microsystems Fabrication Laboratory through $1 million state grant: Upgrades to clean room will enhance university’s research capabilities in photonics, quantum technologies and smart systems August 16th, 2019

Probing the Origin of Alzheimer’s . . . with Transistors: Novel high-sensitivity detector could aid in early diagnosis August 15th, 2019

Chip Technology

ULVAC Launches Revolutionary PZT Piezoelectric Thin-film Process Technology and HVM Solution for MEMS Sensors/Actuators: Enabling Reliable, High-quality Film Production for Next Generation Devices August 16th, 2019

Toppan Photomasks and GLOBALFOUNDRIES Enter into Multi-Year Supply Agreement August 15th, 2019

Sharp meets flat in tunable 2D material: Rice's new atom-flat compounds show promise for optoelectronics, advanced computing August 12th, 2019

New synthesis method opens up possibilities for organic electronics August 7th, 2019

Quantum Computing

RIT to upgrade Semiconductor and Microsystems Fabrication Laboratory through $1 million state grant: Upgrades to clean room will enhance university’s research capabilities in photonics, quantum technologies and smart systems August 16th, 2019

Sharp meets flat in tunable 2D material: Rice's new atom-flat compounds show promise for optoelectronics, advanced computing August 12th, 2019

RIT awarded NSF funding to conceptualize Quantum Photonic Institute: RIT will develop plan for open-access Quantum Foundry for quantum photonic circuits August 7th, 2019

Virginia Tech researchers lead breakthrough in quantum computing July 26th, 2019

Materials/Metamaterials

You're not so tough, h-BN: Rice University chemists find new path to make strong 2D material better for applications August 14th, 2019

A modified device fabrication process achieves enhanced spin transport in graphene August 6th, 2019

Rice lab produces simple fluorescent surfactants: Compounds show promise for use in medicine, manufacturing August 5th, 2019

Wood You Like Some Fresh Water? New treatment for wood makes a membrane to extract fresh water August 5th, 2019

Announcements

uSEE breakthrough unlocks the nanoscale world on standard biology lab equipment August 16th, 2019

Optofluidic chip with nanopore 'smart gate' developed for single molecule analysis: Programmable device enables on-demand delivery of individual biomolecules with feedback-controlled gating for high-throughput analysis August 16th, 2019

ULVAC Launches Revolutionary PZT Piezoelectric Thin-film Process Technology and HVM Solution for MEMS Sensors/Actuators: Enabling Reliable, High-quality Film Production for Next Generation Devices August 16th, 2019

RIT to upgrade Semiconductor and Microsystems Fabrication Laboratory through $1 million state grant: Upgrades to clean room will enhance university’s research capabilities in photonics, quantum technologies and smart systems August 16th, 2019

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

uSEE breakthrough unlocks the nanoscale world on standard biology lab equipment August 16th, 2019

Optofluidic chip with nanopore 'smart gate' developed for single molecule analysis: Programmable device enables on-demand delivery of individual biomolecules with feedback-controlled gating for high-throughput analysis August 16th, 2019

Probing the Origin of Alzheimer’s . . . with Transistors: Novel high-sensitivity detector could aid in early diagnosis August 15th, 2019

Damaged hearts rewired with nanotube fibers: Texas Heart doctors confirm Rice-made, conductive carbon threads are electrical bridges August 14th, 2019

Quantum Dots/Rods

Engineers revolutionize molecular microscopy: Single molecules measure electrical potentials July 12th, 2019

Quantum rebar: Quantum dots enhance stability of solar-harvesting perovskite crystals: Researchers demonstrate that perovskite crystals and quantum dots working together can increase stability of solar materials May 24th, 2019

Coal could yield treatment for traumatic injuries: Rice, Texas A&M, UTHealth scientists discover coal-derived ‘dots’ are effective antioxidant April 25th, 2019

2D gold quantum dots are atomically tunable with nanotubes April 11th, 2019

Research partnerships

Optofluidic chip with nanopore 'smart gate' developed for single molecule analysis: Programmable device enables on-demand delivery of individual biomolecules with feedback-controlled gating for high-throughput analysis August 16th, 2019

Damaged hearts rewired with nanotube fibers: Texas Heart doctors confirm Rice-made, conductive carbon threads are electrical bridges August 14th, 2019

Nanoparticles’ movement reveals whether they can successfully target cancer: Targeting nanoparticles rotate faster and move across larger areas August 9th, 2019

Researchers embrace imperfection to improve biomolecule transport August 8th, 2019

Quantum nanoscience

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

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 June 26th, 2019

Mysterious Majorana quasiparticle is now closer to being controlled for quantum computing: Princeton researchers detect a robust Majorana quasiparticle and show how it can be turned on and off June 14th, 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