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.
