The quantum world – at the scale of
atoms and below – is paradoxical and bizarre. Particles can simultaneously be
both here and there, or mysteriously entangled at a distance. Quantum
technology is about harnessing these strange phenomena to create brand new
technology with extraordinary capabilities.
Throughout his life, Einstein was sceptical to quantum
mechanics – a physical theory that emerged in the early 1900s to describe
nature at the smallest scales. It predicts that nature at its most intimate
levels is ruled by randomness and uncertainty, something Einstein particularly
disapproved of: “I am at all events convinced that He [God] does not play
His persistent questioning of the theory, in search of
a deterministic reality that he was convinced must exist beyond it, led to
discoveries of further aspects of quantum mechanics, such as the mysterious
quantum entanglement which Einstein referred to as “spooky action at a
Not only Einstein was sceptical – quantum mechanics
indeed predicts a mind-boggling world, in many ways completely contradictory to
our everyday-experiences. But the theory has been rigorously tested in many
different ways, and in experiment after experiment confirmed to correctly
predict how nature operates.
From theory to revolution
In the 1930s, quantum theory was essentially complete,
even though many of its consequences remained unexplained. The new understanding
of quantum properties of light and materials led to the invention of the laser
and the transistor – inventions that form the basis of today’s information
technology. Computers, the internet and smartphones have drastically changed
our lives. This was the first quantum revolution.
However, it was long regarded as impossible to control
individual quantum systems such as single atoms, electrons or light particles
(photons). But in the 1980s, scientists managed to develop methods for
measuring and controlling individual atoms and photons, work which was awarded
with the Nobel Prize in physics 2012. In parallel, other researchers developed
electrical components in which they could manipulate single electrons.
Professor Per Delsing, director of the Wallenberg
Centre for Quantum Technology, sees how the abilities to exploit the properties
of individual quantum systems open the door to brand new technology: “It’s not
about incremental change but really a game changer, a paradigm shift.”
A second quantum revolution.
Scientists, policymakers and industrial leaders
across the globe see the revolution coming, and significant investment is now
going into quantum technology. The European Union, the United States, Japan,
China, Australia and Russia are all spending money at the billion-dollar scale
to boost research. Many companies, for example Google and IBM, also put large
efforts and big money in quantum technology.
The counter-intuitive phenomena at the heart of quantum technology
The extraordinary capabilities of the emerging quantum
products – quantum computers way superior to today’s supercomputers,
intercept-proof communications and hypersensitive measuring instruments – are
all based on the almost-mystical phenomena of quantum mechanics. The most
If an electron were on skis, it would be absolutely normal for it to have its skis passing on different sides of a tree. In the world of quantum mechanics, it is fully possible for particles to be in many different places at once. Or to simultaneously have different energy, polarization, or any other state. A famous example is Schrödinger’s cat which is both dead and alive (in a thought-experiment, that is). These ambiguous states are called superpositions.
A superposition can extend between several particles, they are then said to be entangled. A manipulation of one particle affects its entangled partner immediately – even if they are vastly far apart, and without any noticeable transfer of information.
”Spooky action at a distance,” said Einstein skeptically, but experiments have proved it to be correct. However, nobody really knows how or why entanglement works.
In quantum mechanics, the uncertainty principle limits how accurately one can simultaneously know the position and the velocity of an object. The same applies to other interlinked variables, such as time and frequency.
The uncertainty is normally split equally between the two interlinked variables. However, the quantum state of the object can be manipulated so that the uncertainty affects one of the variables more than the other. This is called a squeezed state.
Superpositions are very sensitive. Disturbances cause the superposition to diminish and finally collapse. This process is called decoherence and is one of the greatest challenges to be faced in quantum technology. Why? Because there is an inherent contradiction between isolating a quantum system to avoid decoherence and the need to be able to manipulate it.
The four areas of quantum technology
Quantum technology is often divided into four main
areas: quantum computing, quantum simulation, quantum communication, and
quantum sensing. Read more on their respective page: