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QUANTUM MECHANICS can revolutionize computing, provided its qubits can be made to behave better than conventional digital computer bits. Science, the weekly magazine of the American Association for the Advancement of Science, had a most informative update of this exciting field in December 2, 2016. “Quest for Qubits” by Gabriel Popkin describes quantum computing’s evolution from theory to practice.

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Notes Popkin, “Building a quantum computer has gone from a far-off dream of a few university scientists to an immediate goal for some of the world’s biggest companies.” These include Google, IBM, Intel and Microsoft, though it’s still too early to tell just which one–or more–of competing technologies and companies might win out. A lot is going to happen in the next few years.


Ion-trapping is one quantum-computer technology being investigated. Chris Moore of ionQ Inc. examines equipment in the company’s College Park, Maryland, facility. This and the following image from Science, December 2, 2016.

I’ve shared the basics here at SimanaitisSays in ”Computing with Quanta.” As Popkin puts it, “Qubits outmuscle classical computer bits thanks to two uniquely quantum effects: superposition and entanglement.”

Those of us of a certain age take delight in the term “classical” computer.

Conventional bits have two states, 0 or 1. Superposition gives qubits the capability of having both states identifiable at the same time, thus allowing simultaneous computation.

Entanglement is the quantum oddity of particles interacting from afar, what Albert Einstein called “spooky action at a distance.” This feature means that qubits are capable of sharing their states with others separated by distance. One implication is that processing power doubles with each added qubit.

Popkins observes, “An algorithm using, say, five entangled qubits can effectively do 25 or 32 computations at once, whereas a classical computer would have to do these 32 computations in succession.”

In fact, this processing power would be overkill for menial tasks like word processing or email. Computers spend most of their time with such tasks waiting around for human input. However, such advanced processing power would enhance the mathematics of factoring large numbers (essential in cryptography) or complex simulations of physical or chemical phenomena (think artificial intelligence or weather or climate modeling).

The number of interacting qubits is a crucial measure in quantum computing, with 50 seen as the tipping point. Specialists figure that a 50-qubit device will achieved “quantum supremacy,” a term denoting its doing something beyond the capability of conventional digital technology.


Competing–or potentially cooperative–technologies.

Specialists are active with five different sorts of qubits, each technology having advantages, shortcomings and corporate backers. Competitive though it is, the field has yet to evolve to a secretive stage. Developers still publish results and exchange views at conferences.

One possible outcome might be a hybrid quantum technology combining aspects of, say, superconducting loops, trapped ions and topological qubits. This last technology might tantalize math majors: It involves nonabelian anyons in topologically stable strands. (Who said group theory and topology had no practical applications?) ds

© Dennis Simanaitis,, 2016

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