How Does a Transistor Work?

These are the latest articles and videos I found most interesting.

  1. How Does a Transistor Work?
  2. Detecting rare cancer cells with sound waves
  3. Single Atom Quantum Computing in Silicon
  4. Collective Genius: The Art and Practice of Leading Innovation
  5. Magnetic Propulsion
  6. Strange Spider Mating
  7. Professor Dave Explains: Natural vs. Synthetic Vitamins
  8. M62 – Globular Cluster
  9. Henry David Thoreau

How Does a Transistor Work?

How Does a Transistor Work?
Transistors & The End of Moore’s Law

How does a transistor work? Our lives depend on this device. When I mentioned to people that I was doing a video on transistors, they would say “as in a transistor radio?” Yes! That’s exactly what I mean, but it goes so much deeper than that. After the transistor was invented in 1947 one of the first available consumer technologies it was applied to was radios, so they could be made portable and higher quality. Hence the line in ‘Brown-eyed Girl’ – “going down to the old mine with a transistor radio.”

But more important to our lives today, the transistor made possible the microcomputer revolution, and hence the Internet, and also TVs, mobile phones, fancy washing machines, dishwashers, calculators, satellites, projectors etc. etc. A transistor is based on semiconductor material, usually silicon, which is ‘doped’ with impurities to carefully change its electrical properties. These n and p-type semiconductors are then put together in different configurations to achieve a desired electrical result. And in the case of the transistor, this is to make a tiny electrical switch. These switches are then connected together to perform computations, store information, and basically make everything electrical work intelligently.

Detecting rare cancer cells with sound waves

Massachusetts Institute of Technology (MIT)

A team of engineers from MIT, Penn State University, and Carnegie Mellon University is developing a novel way to isolate rare circulating tumor cells using sound waves to separate them from blood cells. (Learn more: Using sound waves to detect rare cancer cells)

Single Atom Quantum Computing in Silicon

Muon Ray

Using existing Silicon fabrication facilities, it is possible to dope a high purity silicon chip with a single phosphorus donor atom and manipulate the atom using a varying magnetic field to manipulate the quantum spin state of the atom to form a quantum bit or qubit.

The nucleus of the phosphorus atom can store a single qubit for long periods of time in the way it spins. A magnetic field could easily address this qubit using well-known techniques from nuclear magnetic resonance spectroscopy. This allows single-qubit manipulations but not two-qubit operations, because nuclear spins do not interact significantly of each other.

For that, we must transfer the spin quantum number of the nucleus to an electron orbiting the phosphorus atom, which would interact much more easily with an electron orbiting a nearby phosphorus atom. Two-qubit operations would then be possible by manipulating the two electrons with high frequency AC electric fields.

The big advantage of this type of quantum computer, sometimes called the Kane quantum computer after physicist Bruce Kane who suggested the device back in the late 1990’s, is that it is scalable. Since each atom could be addressed individually using standard electronic circuitry, it is straightforward to increase the size of the computer by adding more atoms and their associated electronics and then to connect it to a conventional computer.

The disadvantages of course is that the atoms must be placed at precise locations in the Silicon, using a scanning tunneling microscope. The manipulation of the phosphorus atom spin itself is also problematic as this requires powerful magnetic fields which reduces scalability.

But the big unsolved challenge has been to find a way to address the spin of an individual electron orbiting a phosphorus atom and to read out its value.

To do this requires scientists to implant a single phosphorus atom in a silicon nanostructure and place it in a powerful magnetic field at a temperature close to absolute zero, cooling the chip using liquid helium. This makes it possible to flip the state of an electron orbiting the phosphorus atom by irradiating it with microwaves.

The final step, a significant challenge in itself, is to read out the state of the electron using a process known as spin-to-charge conversion.

The end result is a device that can store and manipulate a qubit and has the potential to perform two-qubit logic operations with atoms nearby; in other words the fundamental building block of a scalable quantum computer.

However, some stiff competition has emerged in the 15 years since Kane published his original design.

In particular, physicists have found a straightforward way to store and process quantum information in nitrogen vacancy defects in diamond, which offer the best possibility to make a functional quantum computer as this structure can produced quantum gate operations that can work at room temperature.

Then there is D-Wave Systems, which already manufactures a scalable quantum computer working in an entirely different way that it has famously sold to companies such as Lockheed Martin and Google.

The big advantage of the Australian design is its compatibility with the existing silicon-based chip-making industry. In theory, it will be straightforward to incorporate this technology into future chips.

Currently, the Australian Kane quantum computer has the highest performance capabilities of any solid state qubit.

Due to the ease of reproducing the diamond NV- centers, their ease of operation without using liquid helium to cool the chip as well as their speed using optics and electronics it seems that diamond based quantum computers are providing the biggest competition to the Kane quantum computer in the race to develop a functioning, gate quantum computer.

Ref: A single-Atom Electron Spin Qubit in Silicon

Collective Genius: The Art and Practice of Leading Innovation

Linda Hill – Harvard – 2015

Great leaders of innovation don’t fit the conventional mold of “good” leadership. They’re not visionaries who set direction and inspire others to follow. Instead, they create the context in which others are both willing and able to innovate. As one leader said, “My job is to set the stage, not to perform on it.” You might think the key to innovation is attracting exceptional creative talent. Or making the right investments. Or breaking down organizational silos. All of these things may help – but there’s only one way to ensure sustained innovation: you need to lead it. They found among leaders a widely shared, and mistaken, assumption: that a “good” leader in all other respects would also be an effective leader of innovation. The truth is, leading innovation takes a distinctive kind of leadership, one that unleashes and harnesses the “collective genius” of the people in the organization. Collective Genius will not only inspire you; it will give you the concrete, practical guidance you need to build innovation into the fabric of your business.

Magnetic Propulsion

Applied Science

This is a neat little demo that shows how permanent magnets can be used to create propulsion along a conductive copper track

Strange Spider Mating

Strange Spider Mating
Static Electric Spider Web

Spiders have strange mating rituals when they are courting a partner.

Professor Dave Explains: Natural vs. Synthetic Vitamins

American Chemical Society

Anti-science mentality is prevalent in modern society. This is evidenced most clearly in a complete distrust of chemicals synthesized in a laboratory. But does the activity of a molecule depend whatsoever on the pathway from which it formed? Let’s see why not.

M62 – Globular Cluster

Deep Sky Videos

We continue our journey through the Messier Catalog with a look at the M62 globular cluster. Featuring Dr Meghan Gray.

Henry David Thoreau

Our inventions are wont to be pretty toys, which distract our attention from serious things. They are but improved means to an unimproved end, an end which it was already but too easy to arrive at; as railroads lead to Boston or New York. We are in great haste to construct a magnetic telegraph from Maine to Texas; but Maine and Texas, it may be, have nothing important to communicate.

The School of Life

We are taught to think of modern civilization as inherently ‘better’ than the pre-industrial age – and take great pride in our gadgets and technology. That’s why we need to tap into the caustic, liberating mindset of the great American political thinker, Thoreau – who escaped modern civilization to go and live in a cabin in the woods…

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