quantum computing fitna _______________?

WaPo |  There is a race to build quantum computers, and (as far as we know) it isn’t the NSA that is in the lead. Competing are big tech companies such as IBM, Google, and Microsoft; start-ups; defense contractors; and universities. One Canadian start-up says that it has already developed a first version of a quantum computer. A physicist at Delft University of Technology in the Netherlands, Ronald Hanson, told Scientific American that he will be able to make the building blocks of a universal quantum computer in just five years, and a fully-functional demonstration machine in a little more than a decade.

These will change the balance of power in business and cyber-warfare.  They have profound national-security implications, because they are the technology equivalent of a nuclear weapon.

Let me first explain what a quantum computer is and where we are.

In a classical computer, information is represented in bits, binary digits, each of which can be a 0 or 1.  Because they only have only two values, long sequences of 0s and 1s are necessary to form a number or to do a calculation. A quantum bit (called a qbit), however, can hold a value of 0 or 1 or both values at the same time — a superposition denoted as “0+1.”  The power of a quantum computer increases exponentially with the number of qubits. Rather than doing computations sequentially as classical computers do, quantum computers can solve problems by laying out all of the possibilities simultaneously and measuring the results.

Imagine being able to open a combination lock by trying every possible number and sequence at the same time. Though the analogy isn’t perfect — because of the complexities in measuring the results of a quantum calculation — it gives you an idea of what is possible.

There are many complexities in building a quantum computer: challenges in finding the best materials from which to generate entangled photon pairs; new types of logic gates and their fabrication on computer chips; creation and control of qubits; designs for storage mechanisms; and error detection. But breakthroughs are being announced every month. IBM, for example, has just announced that it has found a new way to detect and measure quantum errors and has designed a new qubit circuit that, in sufficient numbers, will form the large chips that quantum computers will need.

Most researchers I have spoken to say that it is a matter of when — not whether — quantum computing will be practical. Some believe that this will be as soon as five years; others say 20 years.  IBM said in April that we’ve entered a golden era of quantum-computing research, and predicted that the company would be the first to develop a practical quantum computer.