Quantum Dot Challenge

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This page provides a sample module for the Quantum Dot Challenge. Extensions, modifications, and other implementation options can be found at: Quantum Dot Extensions.

Contents

Background

Quantum Dots are nanoscopic particles of semiconductor materials. They range in size from roughly 2-20nm and possess a variety of unique properties. They are unique in that their electron band gap, and therefor their emission wavelengths, can be predicted by the size of the dot. (A band gap is the 'space' between two possible energy levels for an electron confined to a particle. When an electron jumps from one state to the other it releases a photon at a wavelength which will compensate for the energy difference. The amount of energy between the two levels determines the wavelength of the photon.) Since the size of the dots can be controlled by the environment in which they are created, it is possible to create quantum dots which emit light at specific wavelengths. There are currently attempts to use the dots to create low power consumption LED displays. The dots also been functionalized onto biological molecules and used as dyes for microscope observation of biological systems. There is speculation that they may eventually be usable for quantum computing.

Image:Quantum_dot3.jpg

Exposed to ultraviolet light, the dots fluoresce with a color determined by the dot size. A rainbow of colors can be emitted from a single material simply by changing the dot size.
Exposed to ultraviolet light, the dots fluoresce with a color determined by the dot size. A rainbow of colors can be emitted from a single material simply by changing the dot size.

In this activity you will be assembling and using a table which will help you in conceptualizing the functionality of quantum dots. Please note that what you are building is a very crude mock up of the Quantum dot assembly process. Real quantum dots will self assemble under the correct conditions and do not require outside intervention. They also have a three rather then a two dimensional spherical lattice structure held together by interatomic forces.

Materials

Construction

You can find details on how to build the quantum dot assembly table itself here. There is information on how to properly set up the configurations of the table's magnets on this page. When you are done building, you can download and install a control interface for the table from here.

Challenge

Once you have assembled your table you can begin the real challenge. Your goal is to trap a large particle (ping pong ball) using an assembled magnetic trap (your quantum dot). Once you have downloaded and installed the software provided you can connect the LEGO NXT unit to your computer via USB cable and begin. Start the particles (lego pyramids) under the notches in the strip of LEGOs running across the base with their bottom edges pointing up. Attempt to grab them with the crane, deliver them to a magnetic point over the floor lattice, and drop them off. A video sample of the process is available.

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