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Researchers Create Perfect Quantum Dots with Single-Atom Precision

Researchers Create Perfect Quantum Dots with Single-Atom Precision | Research Capacity-Building in Africa | Scoop.it

A team of physicists from the Paul-Drude-Institut für Festkörperelektronik (PDI) in Berlin, Germany, NTT Basic Research Laboratories in Atsugi, Japan, and the U.S. Naval Research Laboratory (NRL) has used a scanning tunneling microscope to create quantum dots with identical, deterministic sizes. The perfect reproducibility of these dots opens the door to quantum dot architectures completely free of uncontrolled variations, an important goal for technologies from nanophotonics to quantum information processing as well as for fundamental studies. The complete findings are published in the July 2014 issue of the journal Nature Nanotechnology.

 

Quantum dots are often regarded as artificial atoms because, like real atoms, they confine their electrons to quantized states with discrete energies. But the analogy breaks down quickly, because while real atoms are identical, quantum dots usually comprise hundreds or thousands of atoms - with unavoidable variations in their size and shape and, consequently, in their properties and behavior. External electrostatic gates can be used to reduce these variations. But the more ambitious goal of creating quantum dots with intrinsically perfect fidelity by completely eliminating statistical variations in their size, shape, and arrangement has long remained elusive.

 

Creating atomically precise quantum dots requires every atom to be placed in a precisely specified location without error. The team assembled the dots atom-by-atom, using a scanning tunneling microscope (STM), and relied on an atomically precise surface template to define a lattice of allowed atom positions. The template was the surface of an InAs crystal, which has a regular pattern of indium vacancies and a low concentration of native indium adatoms adsorbed above the vacancy sites. The adatoms are ionized +1 donors and can be moved with the STM tip by vertical atom manipulation. The team assembled quantum dots consisting of linear chains of N = 6 to 25 indium atoms; the example shown here is a chain of 22 atoms.

 

Stefan Fölsch, a physicist at the PDI who led the team, explained that "the ionized indium adatoms form a quantum dot by creating an electrostatic well that confines electrons normally associated with a surface state of the InAs crystal. The quantized states can then be probed and mapped by scanning tunneling spectroscopy measurements of the differential conductance." These spectra show a series of resonances labeled by the principal quantum number n. Spatial maps reveal the wave functions of these quantized states, which have n lobes and n - 1 nodes along the chain, exactly as expected for a quantum-mechanical electron in a box. For the 22-atom chain example, the states up to n = 6 are shown.


Via Dr. Stefan Gruenwald
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PHOTOS: Stunning images of a tribe from Sudan

PHOTOS: Stunning images of a tribe from Sudan | Research Capacity-Building in Africa | Scoop.it
Complete photographic series.

Via Robert DesJarlait
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Web-Based Course Assessment Tool with Direct Mapping to Student Outcomes


Via Ana Cristina Pratas
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Does Higher Education really cause economic growth? - by Donald Clark

Does Higher Education really cause economic growth? - by Donald Clark | Research Capacity-Building in Africa | Scoop.it

Via Ana Cristina Pratas
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Trends 2015 - Learning and Teaching in European Universities


Via Ana Cristina Pratas
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Татьяна Фокина's curator insight, June 1, 8:57 AM

добавить ваше понимание ...

María Dolores Díaz Noguera's curator insight, June 5, 10:50 AM

Tendencias en las Universidades Europeas...Trends 2015 - Learning and Teaching in European Universities | @scoopit via @AnaCristinaPrts http://sco.lt/...

Joaquin Sevilla's curator insight, June 8, 5:57 AM

Aparte de removelo por ahí habría que leerselo... cosa que aún no he hecho

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Using a design-based research study to identify principles for training instructors to teach online

Using a design-based research study to identify principles for training instructors to teach online | Research Capacity-Building in Africa | Scoop.it
Using a design-based research study to identify principles for training instructors to teach online

Via Ana Cristina Pratas
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Paula King, Ph.D.'s curator insight, June 2, 2:47 PM

ALWAYS INTERESTING

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Transforming Information Literacy for Today’s K-12 Learners Through t…

Transforming Information Literacy …
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The Daring Librarian: Makerspace Starter Kit

The Daring Librarian: Makerspace Starter Kit | Research Capacity-Building in Africa | Scoop.it
We have, however, recently expanded upon our Makerspace offerings thanks to being inspired by several of my librarian friends in our amazing #TLChat PLN! Kids can come in during lunch or when they've finished their work to explore, craft, and create in the Library Media Center.


I re-purposed 4 empty study carrels for this Makerspace center at the top corner of our library.  The grouping includes a Lego Creation Station, a Duct Tape Craft Cubby, and a Makey Makey Coding Corner."


Via John Evans
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Leslie Kelsey's curator insight, June 15, 1:57 PM

Makerspaces are coming to our County - Solana Beach is leading the way! 

Willemijn Schmitz's curator insight, June 16, 4:40 AM

Vooral de Duct Tape Craft Cubby spreekt me aan!

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The Periodic Table: For the Record: Recent U graduate appalled by President Kaler's Counterpoint on Research Ethics

The Periodic Table: For the Record: Recent U graduate appalled by President Kaler's Counterpoint on Research Ethics | Research Capacity-Building in Africa | Scoop.it
For the Record: Recent #umn grad appalled by President Kaler's Counterpoint on Research Ethics
http://t.co/cVziacN4mw
#umn #mnleg #stribpol
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Harvard, Syracuse Researchers Caught Lying to Boost Obama Climate Rules - Breitbart News

Harvard, Syracuse Researchers Caught Lying to Boost Obama Climate Rules - Breitbart News | Research Capacity-Building in Africa | Scoop.it
Are we to believe that a group of researchers who had previously received some $45 million in grants from EPA, no doubt hoping for more in the future, could possibly not have any dog in this fight?
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6 Skills Even the Strongest Leaders Need to Practice

6 Skills Even the Strongest Leaders Need to Practice | Research Capacity-Building in Africa | Scoop.it
Strong, effective leadership results from continuously learning, regularly accepting feedback, and consistently practicing what you learn. Here are 6 skills that

Via Anne Leong
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Jerry Busone's curator insight, May 30, 8:46 AM

Good reminder and mirrors well "Off the Bench Leading "

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Great Leadership: Leadership Strengths Can Turn into Weaknesses

Great Leadership: Leadership Strengths Can Turn into Weaknesses | Research Capacity-Building in Africa | Scoop.it

Via Anne Leong
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3 Ways a Leader’s Attitude Impacts the Team

3 Ways a Leader’s Attitude Impacts the Team | Research Capacity-Building in Africa | Scoop.it
3 ways your attitude is impacting your team's passion and enthusiasm. Make sure you aren't contributing to your employee's attitude problem.

Via Anne Leong
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Pamela Perry King's curator insight, June 4, 10:07 AM

Attitude is like a cold....cough on someone and spread the joy!

Dr. Deborah Brennan's curator insight, June 4, 10:39 AM

Leaders have to be self aware.  What they say, do, even think effects the whole school!

Dr. Deborah Brennan's curator insight, June 10, 5:30 PM

Attitude matters!  A teacher's attitude affects the students - a leader's attitude sets the tone for the entire building.  Someone once said, "the principal should be the happiest person in the building" (it is the principal, more than others, who controls so much of what goes on). 

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World Environment Day 2015: The costs of using up Earth's natural resources

World Environment Day 2015: The costs of using up Earth's natural resources | Research Capacity-Building in Africa | Scoop.it
The World Environment Day theme for 2015 is 'Seven Billion Dreams. One Planet. Consume with Care'.
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