
	Where results make sense

Topic: Quantum dot

Related Topics

RHEED

Fluorescence

Phosphorescence

Fluorescent lamp

Cadmium

Phosphor

Ruby

Neelanjali Ruby

Rajaratna Ruby

Aequorea victoria

Fluorescent lamp

	Quantum dot - Wikipedia, the free encyclopedia
		Quantum dots are particularly significant for optical applications due to their theoretically high quantum yield.
		In semiconductors, quantum dots are small regions of one material buried in another with a larger band gap.
		To this end, Quantum Dots have quickly filled in the role, being found to be superior to traditional organic dyes on several counts, one of the most immediately obvious being brightness (owing to the high quantum yield) as well as their stability.
	en.wikipedia.org /wiki/Quantum_dots (1484 words)

	Quantum Dot Core Concepts (Site not responding. Last check: 2007-11-06)
		Quantum dots commercialized by Evident Technologies Inc. They consist of quantum dots combined with multiple material systems and shell structures that serve both to increase dot stability (fluorescent lifetime), and to adjust their surface properties according to specific commercial applications.
		Quantum dots have a range of useful electrical and optical properties that diverge in character from those of bulk material.
		The dimensions of a quantum dot are measured in nanometers (typically between 2 and 10).
	www.evidenttech.com /qdot-definition/quantum-dot-glossary.php (1324 words)

	C&EN: TODAY'S HEADLINES - QUANTUM DOT ADVANCES
		Quantum dots and multiphoton microscopy can be combined to obtain images such as these of the surface of adipose tissue surrounding the ovary.
		The combination of quantum dots and multiphoton microscopy (in which multiple lower energy photons are used to excite a higher energy electron transition) lessens potential tissue damage in two ways.
		In contrast to earlier quantum dot studies, Webb and his colleagues don't observe blinking on a millisecond or faster timescale, which Webb attributes to the dots being in solution rather than stuck on a surface.
	pubs.acs.org /cen/topstory/8123/8123notw6.html (595 words)

	'Quantum dots' could form basis of new computers
		Quantum computers would take advantage of a strange phenomenon described by quantum theory: Objects, such as atoms or electrons, can be in two places at the same time, or they can exist in two states at the same time.
		The quantum dots themselves are only about 180 nanometers in diameter – about 5,000 of them could stretch across the width of a grain of sand.
		When quantum dots contain only one electron in their outermost level, their spins can be detected by analyzing the flow of electricity through the dots, Chang said.
	news.uns.purdue.edu /html4ever/010917.Chang.quantum.html (1055 words)

	UB Reporter: Quantum-dot syntheses developed
		Quantum dots are tiny semiconductor particles generally no larger than 10 nanometers that can be made to fluoresce in different colors depending on their size.
		Quantum dots also are of great interest for energy applications because they can produce electrons when they absorb light, making possible extremely efficient solar-energy devices.
		The UB group's quantum dots are composed of an indium phosphide core surrounded by a zinc selenide shell to protect the surface.
	www.buffalo.edu /reporter/vol37/vol37n4/articles/QuantumDots.html (873 words)

	NIST Research on Quantum Systems for the ‘Next’ Information Age
		For quantum communications applications, in which data are transmitted in the form of single photons (“flying qubits”;), NIST is developing a measurement infrastructure for characterizing the performance of quantum components and systems.
		A quantum dot, when excited, acts like an atom and thus emits a photon with a well-characterized frequency that can be used to create a “photon turnstile,” which eventually will be used in a quantum cryptography system on the NIST test-bed.
		The “quantum dot” systems also could be used to better understand electrical processes in these systems and, ultimately, may help produce the next generation of optical devices, such as laser diodes, photodetectors, and optical amplifiers.
	www.nist.gov /public_affairs/factsheet/quantum.htm (1865 words)

	Chapter 5: Quantum Dot Lasers
		Thus, the challenge in realizing quantum dot lasers with operation superior to that shown by quantum well lasers is that of forming high quality, uniform quantum dots in the active layer.
		The problem that plagued these quantum dot arrays was their exceedingly low optical efficiency: high surface-to-volume ratios of these nanostructures and associated high surface recombination rates, together with damage introduced during the fabrication itself, precluded the successful formation of a quantum dot laser.
		As with the demonstration of the advantages of the quantum well laser that preceded it, the full promise of the quantum dot laser must await advances in the understanding of the materials growth and optimization of the laser structure.
	www.wtec.org /loyola/nano/05_04.htm (845 words)

	Quantum dots for sale - The Industrial Physicist
		Two quantum dots connected by a wire behave somewhat like atoms in a molecule, with different energy levels, a property that might be useful as a switch in a quantum computer.
		Because of their tiny size, quantum dots behave according to the rules of quantum physics, which describe the behavior of atoms and smaller particles, rather than those of classical physics, which describe the behavior of objects consisting of many atoms.
		Quantum dots form when a thin semiconductor film buckles under the stress created when its lattice structure differs slightly in size from that of the material on which it is grown, explains Jerry Floro, a researcher at Sandia National Laboratories (Albuquerque, NM).
	www.aip.org /tip/INPHFA/vol-9/iss-1/p14.html (2424 words)

	Quantum dot DNA test
		Each dot is made from semiconductor crystals of cadmium selenide encased in a zinc sulfide shell as small as 1 nanometer in diameter (one millionth of a millimeter).
		To capture the quantum dots, they made porous microbeads of polystryene (which is used to make Styrofoam brand plastic foam) and seeded these with the zinc sulfide-capped cadmium selenide nanocrystals.
		To demonstrate the use of these quantum dots in DNA analysis, the researchers prepared microbeads of three colors, or spectral wavelengths, and attached them to strips of genetic material.
	www.medicalnewstoday.com /medicalnews.php?newsid=27546 (663 words)

	Sandia National Laboratories – News Release: Sandia researchers use quantum dots as a new approach to solid-state ...
		The quantum dots strongly absorb light in the near UV range and re-emit visible light that has its color determined by both their size and surface chemistry.
		Quantum dot phosphors are integrated with an LED chip, from Cree, Inc., that emits in the near ultraviolet at 400 nanometers by encapsulating the chip with a dot-filled epoxy, creating a dome.
		The quantum dots in the dome absorb the invisible 400 nanometer light from the LED and reemit it in the visible region — a principle similar to that used in fluorescent lighting.
	www.sandia.gov /news-center/news-releases/2003/elect-semi-sensors/quantum.html (1186 words)

	Method slashes quantum dot costs by 80 percent
		In an important advance toward the large-scale manufacture of fluorescent quantum dots, scientists at Rice University have developed a new method of replacing the pricey solvents used in quantum dot synthesis with cheaper oils that are commonplace at industrial chemical plants.
		Quantum dots typically cost more than $2,000 per gram from commercial sources, and pricey solvents like octadecene, or ODE - the least expensive solvent used in quantum dot preparation today - account for about 90 percent costs of raw materials.
		The reproducible synthesis of high-quality quantum dots became a reality in the early 1990s when researchers at MIT pioneered a new method of producing quantum dots with uniform sizes and well-defined optical signatures.
	www.eurekalert.org /pub_releases/2005-09/ru-msq090705.php (610 words)

	Cornell News: quantum dot imaging
		In this image, collagen is imaged in blue by second harmonic generation while quantum dots inside the capillary are imaged in yellow by two-photon fluorescence excitation.
		Quantum dots are microscopic metal or semiconductor boxes (in this case cadmium selenide-zinc sulfide) that hold a certain number of electrons and, thus, have a wide number of potential applications in electronics and photonics.
		The quantum dots were 6 to 10 nanometers in diameter.
	www.news.cornell.edu /releases/May03/quantum_dots.hrs.html (924 words)

	Quantum computers are a quantum leap closer, say Purdue physicists
		Future computers that use quantum dots to store and process digital information might outperform conventional computer circuits because of both the new transistors' smaller size and their potential to solve problems that would take centuries on today's machines.
		But for a quantum computer, whose bits can be in two quantum states at once – both on and off at the same time – many solutions could, in theory, be explored simultaneously, allowing for a solution in hours rather than lifetimes.
		The quantum dots (the two small circular areas shown adjacent to one other in the center of the image) are puddles of about 40-60 electrons.
	news.uns.purdue.edu /UNS/html4ever/2004/040429.Chang.parallel.html (1515 words)

	EETimes.com - Purdue builds quantum-computing semiconductor chip
		The resulting quantum dot itself was centered inside that domain, and measured between 50 and 120 nm, depending on the voltages applied to the electrodes.
		Interaction between the dots was confirmed by measuring the differential conductance of the transistor as the bias voltage between the source and drain was varied.
		In passing current through the quantum dot, the team observed that two peaks existed in the differential conductance of the SET as voltage was varied between the source and drain.
	www.eet.com /story/OEG20010924S0101 (1350 words)

	Physics Today May 2001
		Fabrication of self-assembled quantum dots begins with some form of atomic deposition onto the surface of a semiconductor substrate, where the deposited material is chosen to have a smaller bandgap than the substrate.
		The capacitancevoltage characteristic of quantum dot samples typically manifests six maxima, as shown in figure 3, where the indicated maxima denote the loading of one through six electrons into the dot.
		The nonvanishing angular momentum of quantum rings in the presence of a magnetic field is closely related to the fascinating physics of the so-called persistent currents in mesoscopic rings.
	www.physicstoday.org /pt/vol-54/iss-5/p46.html (3213 words)

	Define quantum dot - a definition from Whatis.com (Site not responding. Last check: 2007-11-06)
		A quantum dot is a particle of matter so small that the addition or removal of an electron changes its properties in some useful way.
		Quantum dots typically have dimensions measured in nanometers, where one nanometer is 10
		In the extreme, the position of a single electron in a quantum dot might attain several states, so that a quantum dot could represent a byte of data.
	whatis.techtarget.com /definition/0,,sid9_gci518016,00.html (297 words)

	Quantum computing FAQ
		A quantum dot is essentially a zero-dimensional artificial atom, isolated on (or in) a semiconductor substrate.
		Quantum Information Program at NIST quantum information science project at NIST http://qubit.nist.gov/ A near-term goal of this program is to produce the first (prototype) quantum logic processor consisting of approximately 10 qubits.
		Quantum Physics Division of the Physics Laboratory of NIST http://physics.nist.gov/Divisions/Div848/div848.html [- ] develops the laser as a precise measurement tool; [- ] investigates new ways to direct and control atoms and molecules; [- ] studies the interaction of ultrashort light pulses with matter; and [- ] measures nanometer scale motion of biological molecules.
	www.rdrop.com /~cary/html/quantum_c_faq.html (7848 words)

	ScienceDaily: Method Slashes Quantum Dot Costs By 80 Percent
		Quantum dot -- A quantum dot, also called a semiconductor nanocrystal, is a semiconductor crystal whose size is on the order of just a few nanometers.
		Quantum number -- A quantum number is any one of a set of numbers used to specify the full quantum state of any system in quantum mechanics.
		Quantum entanglement -- Quantum entanglement is a quantum mechanical phenomenon in which the quantum states of two or more objects have to be described with reference to each other, even though the individual objects may be...
	www.sciencedaily.com /releases/2005/09/050909073701.htm (1908 words)

	Los Alamos shows path to 'nanocrystal quantum dot' lasers (Site not responding. Last check: 2007-11-06)
		Quantum dots are so small that quantum mechanical effects come into play in controlling their behavior.
		Just as in the semiconductor laser chip in a CD player, the goal of a quantum dot laser is to manipulate the material into a high energy state and then properly convert it to a low energy state.
		Quantum dots offer this performance over a range of temperatures, making them suitable for a variety of applications, and also can be "tuned" to emit at different wavelengths, or colors.
	www.lanl.gov /worldview/news/releases/archive/00-134.shtml (707 words)

	How the Intelligent Chip Works - Definitive Explanation
		Highly reflective metals are used as cladding for quantum dot arrays for a very clever reason: to promote greater photon emission by trapping the photons longer and allowing the photon chain reaction to progress further.
		A "quantum wire" is produced by cutting away most of the quantum well's top surface to obtain a thin "slice" of the top P layer and the N layer.
		Standard quantum theory describes a quantum system as a "superposition of states that is invariably and instantly destroyed by measurement of the system." This destruction of the quantum system is referred to as the collapse of the wave-function of probability amplitudes that defines the system.
	www.machinadynamica.com /machina64.htm (3473 words)

	Scientists find flaw in quantum dot construction
		When experimental scientists blasted the quantum dots with a beam of light in previous studies, the wetting layer caused interference, instead of allowing the light to enter the dot and trigger the quantum state, he explained.
		The Article states that quantum dots have manufacturing problems, that need to be tackled before important work can be done.
		Quantum pc wiil come but again at what price do we end up paying for say quantum research in mind control wow a bilion dolllar budget and someone is in =controll= and it will not be us.
	www.physorg.com /news3009.html (1073 words)

	NREL: News Release - Quantum Dot Materials Can Reduce Heat, Boost Electrical Output (Site not responding. Last check: 2007-11-06)
		In a paper published in a May issue of the American Chemical Society's Nano Letters journal, an NREL team found that tiny "nanocrystals," also known as "quantum dots," produce as many as three electrons from one high energy photon of sunlight.
		The recent work demonstrates MEG in quantum dots of a second semiconductor material, lead sulfide.
		Beyond potential use for photovoltaic cells, similar quantum dot technology may someday be used in photoelectrochemical cells, which could become a clean and renewable way to produce hydrogen directly from water and sunlight.
	www.nrel.gov /news/press/2005/1805_quantum_dot.html (403 words)

	QCADesigner - Basic QCA Tutorial (Site not responding. Last check: 2007-11-06)
		We can use quantum physics to our advantage because the smaller a quantum dot is physically, the higher the potential energy necessary for an electron to escape.
		As such, they control the rate at which electrons are able to quantum mechanically tunnel between the dots in the cell and therefore switch the polarization of the cell.
		As the clock signal is switched low, the potential barriers between the dots are raised high and the electrons are localized such that a polarization is developed based on the interaction of their neighbors; i.e.
	www.qcadesigner.ca /tutorials/QCATutorial.html (2537 words)

	The Latest In Quantum-Dot Switches: Science Fiction in the News
		The two puddles are placed inside a semiconductor; each puddle is given a final, unpaired electron which gives the quantum dot a net spin of up or down.
		Finally, the two dot system is tuned so that the two unpaired electrons become "entangled" - that is, they begin to interact with each other.
		The hope for quantum computing is that, since a quantum computer's bits could be in two quantum states at once - both on and off - it might be possible to explore many different solutions simultaneously.
	www.technovelgy.com /ct/Science-Fiction-News.asp?NewsNum=115 (383 words)

	Quantum Dot Products
		Type 1 and 2 EviTags are quantum dots that are stable in water and have synthetic and natural surfaces that are ready to conjugate with easy to use protocols.
		Quantum Dots Water Stabilized for use as a nanobio labels and tags
		Quantum dots are semiconductor crystals typically between 1 and 10 nanometers in diameter and have unique properties between that of single molecules and bulk materials.
	www.evidenttech.com (433 words)

Try your search on: Qwika (all wikis)