Friday, March 04, 2005
Quantum Quandary
Emmanuel Knill from the National Institutes of Standards and Technology has come up with a way to eliminate errors from quantum computers. Such supercomputers are the holy grail of everyone hobbled by inadequate computer speed. But prototypes have been woefully unrealiable. Knill's solution could make such machines work.
Ordinary computers use millions of transistors on a chip to perform mathematical and logical operations. The transistors talk to each other in words, or bits, of binary code, switching on and off to telegraph 0s and 1s. Quantum computers would use properties of individual atoms, such as their spin and magnetic properties, to do the same and compute at untold speeds. A quantum binary word is called a qubit.
But there's a hitch. Qubits are very prone to outside electronic noise and can easily get garbled. Knill's solved the problem by building a pyramid-style hierarchy of qubits, and teleportation of data at key intervals to continuously double-check the accuracy of qubit values. That's right, teleportation. It's one of the many odd behaviors permited on the atomic scale level by the laws of quantum mechanics. Last year, NIST physicists showed that teleporting works. They transferred key properties of one atom to another atom without using a physical link.
"There has been a tremendous gap between theory and experiment in quantum computing," Knill says. "It is as if we were designing today's supercomputers in the era of vacuum tube computing, before the invention of transistors. This work reduces the gap, showing that building quantum computers may be easier than we thought. However, it will still take a lot of work to build a useful quantum computer."
Ordinary computers use millions of transistors on a chip to perform mathematical and logical operations. The transistors talk to each other in words, or bits, of binary code, switching on and off to telegraph 0s and 1s. Quantum computers would use properties of individual atoms, such as their spin and magnetic properties, to do the same and compute at untold speeds. A quantum binary word is called a qubit.
But there's a hitch. Qubits are very prone to outside electronic noise and can easily get garbled. Knill's solved the problem by building a pyramid-style hierarchy of qubits, and teleportation of data at key intervals to continuously double-check the accuracy of qubit values. That's right, teleportation. It's one of the many odd behaviors permited on the atomic scale level by the laws of quantum mechanics. Last year, NIST physicists showed that teleporting works. They transferred key properties of one atom to another atom without using a physical link.
"There has been a tremendous gap between theory and experiment in quantum computing," Knill says. "It is as if we were designing today's supercomputers in the era of vacuum tube computing, before the invention of transistors. This work reduces the gap, showing that building quantum computers may be easier than we thought. However, it will still take a lot of work to build a useful quantum computer."
