Thursday, August 12, 2010

Quantum Legos

In the Paleozoic era of conventional computing (45 years ago), one crucial problem was how to build a fast switchable multi-bit MEMORY ARRAY. Many schemes from vacuum tubes to transistors were devised for storing and changing the 0s and 1s inside the computer's brain. How many of you remember the checker-board arrays of tiny magnetic donuts threaded by little wires that were once the hottest thing in computer memory tech (along with magnetic disc drives the size of washing machines)?

Quantum computers have the same problem--what to use for memory? But in the quantum case you not only have to store 0s and 1s but all possible quantum superpositions of a 0 and a 1--the so-called "quantum bit" or "qubit". Several physical systems from single photons to superconducting loops have been suggested for realizing qubits including single ions.

An ion is an atom or molecule that has become electrically charged by adding or removing electrons.

Isolating a single ion has up till now involved a large and complicated array of electric and magnetic fields that form an "ion trap"--sometimes called Penning or Paul traps. But recently scientists at NIST (National Institute of Standards and Technology) have developed a small silicon chip (pictured above) that can trap single ions, opening the possibility of assembling large arrays of ionic qubits by stacking these silicon modules like Lego blocks.

The development of "Quantum Legos" by physicists Dietrich Leibfried, Jason Amini and their colleagues at NIST may well be the crucial breakthrough that takes quantum computers out of the laboratory and into our bedrooms.

From Popular Science August 2010. Thanks brother Tom.

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