I work at a company that designs and builds lasers, ranging from small ones like the pointers you can buy in a local shop to industrial lasers that can precisely cut all kinds of material or even weld metal. We also manufacture lasers used in operating theatres to perform precision surgery.

A unique technology derived from quantum interactions between light and matter with many different applications.

We could not understand modern medicine without quantum physics. At the hospital where I work as a doctor, we often use MRI scans to detect tumours and other types of pathologies. Quantum physics is key to understanding this technology's basic processes. In addition, lasers (another quantum technology) have become essential tools for extreme-precision surgery. These are just two examples of how quantum physics can help medicine!

Since I live in a small mountain village with few shops, I have got used to buying everything I need online. But there are many people in the village, including my grandmother, who prefer to drive an hour to the city rather than enter their details on the internet, because they are afraid of hacker attacks.

Although this is a major danger, I am not worried. I have read that there are many people dedicated to studying new ways to improve the communications security. It seems the most promising techniques are related to the exotic properties of quantum physics!

We cannot describe the properties of two entangled particles separately.

If we measure the polarisation of a photon (the plane of oscillation of a light wave), the polarisation of the entangled photon will also be instantly determined!

We can only entangle quantum particles, which we can use to teleport information, for example.

Applications: this is the basis for most of the new quantum technologies, such as computing and cryptography.

In quantum physics, measurement means extracting information from a system in some way.

Measuring a quantum system can change its state: for example, polarisation measurements can switch the polarisation from vertical to horizontal.

Contrary to what happens in the macroscopic world, in quantum physics the order of measurements can vary the final result.

Applications: increasing the security of cryptography. The inevitable effect of measurement on a particle's state may be evidence of a spy's presence.

If everything is made up of quantum particles (atoms, etc.), how can the macroscopic world not have the same “strange” properties as quantum particles?

The correspondence principle states that classic behaviour is the statistical result of the random behaviour of a large number of quantum particles.

We do not yet know where the boundary between quantum and classical theory lies.

Quantum dots are nanoparticles that have the interesting property of emitting and absorbing specific colours of light, which can be adjusted by changing the size and composition of the dot.

Applications: macromolecular markers, microscopy, computing, improving the efficiency of photovoltaic cells and LEDs, etc.

There are already LED televisions that work with quantum dots.

On many occasions throughout the history of science a new theory has replaced an older one: heliocentrism supplanted geocentrism, evolution supplanted catastrophic and Lamarckian theories. No-one can be sure this will not happen with quantum physics.

Should we then worry that all the efforts we are making now in this field will one day be in vain? Or can we carry on calmly, given that the current theory works for the moment, that is, it allows us to make predictions and develop new technologies?

We often feel that quantum physics is extremely difficult to understand and this frequently leads to misunderstandings. Is it really that way, compared with other disciplines such as astronomy and chemistry, or it is simply because the concepts are unintuitive? Why should we be more surprised by the random nature of quantum physics than the existence of gravity?

Their applications in all fields of human activity will radically change our lives, just as electricity and electronics once did. We must invest as much as we can in their development, to make them commercially viable as soon as possible. 

We should not be fooled by illusory promises. We have gone very far with traditional technologies and we still have a long way to go: we should keep the current investment in quantum technologies at the same level. Let scientists do their work and continue to research, focusing on maintaining and improving the technologies that we already have. 

Research into quantum physics and its applications is positive, but we currently have other far more important and pressing issues, such as hunger, poverty, wars and terrorism. Let us maintain research, but invest our money to find solutions to the major problems our society has today.  

Quantum technologies are very promising, but if they are to be effective, they require solid knowledge of their foundations. We should invest in fundamental research: a better understanding of the foundations of quantum physics will naturally lead to the development of its applications.