I have done some study about quantum computing and my humble conclusion are some kind of amazing. My feelings are mixed. Terrifying and full of admiration.

Quantum computers can be a huge help in the way it can do fantastic speedy work (calculations) but it can be used to do a lot of harm.

The worldwide race to the quantum computer is in full swing. Google, Microsoft, IBM, Baidu, Alibaba and Tencent are fighting to make the first stable quantum computer. Quantum computers are intelligent and powerful computers that process information in a new way and in this way can force large and important breakthroughs. Quantum computers are expected to open doors to possibilities that are currently unthinkable.

With quantum computing we could calculate how the perfect medicine can be made at the molecular level, by which cause changes in the climate occur. But also how problems with mobility can be solved or which material is superconducting at room temperature, which would have an enormous impact on our energy supply.

The developments of this 'supercomputer' type are going very fast. Why is there so much excitement and is it justified?

The term quantum computer was first mentioned in 1981 by the American physicist Richard Feynman. The word 'quantum' comes from quantum mechanics, the branch of natural sciences that deals with the study of the behavior of atomic and subatomic particles ('quantum' comes from the Latin word that stands for 'quantity'). Quantum computers have the potential to be able to perform calculations much faster than traditional computers and even faster than the supercomputers we use today. For example, a stable quantum computer can cause an unprecedented growth spurt in the field of artificial intelligence.

The difference with classic computers Classic computers use a memory that stores information by means of bits; each bit stands for 0 or 1 (on or off, yes or no). A quantum computer, on the other hand, uses quantum bits (qubits, or qbits). A qubit can take a 0, a 1 or a quantum superposition; the latter means that it can assume all possible values (0 and 1). I try to clarify what exactly that means, using the following example.

A traditional computer with two bits can store information in four possible combinations: 00, 01, 10 and 11. A quantum computer can assume all these combinations at the same time. A series of thirty zeros and ones makes about one billion different combinations possible; a classic computer can only occupy one of these combinations at the same time, but a quantum computer can take them all at once and can thus make a billion calculations in the time when a classic computer makes one. This makes it possible to compare a quantum computer with a classic computer with a billion processors, but in one piece of hardware. The phenomenon that a quantum computer can make multiple calculations simultaneously is also called quantum parallel processing.

Try to imagine:

1 qubit has the same value as 2 bits.

2 qubit has the same value as 4 bits, etc

As the number of qubits increases, the calculation power increases exponentially with the number of qubits. If this number is n, for example 8, the processor will perform the same calculation for all possible inputs (2n = 256) at once. A classic computer would have to perform the same operation 256 times. Of course not all 256 inputs and outputs will be useful, but some will. A quantum computer is therefore able to perform parallel calculations very quickly on a dataset that can not be processed even with the most fast conventional computers.

Now try to imagine a computer with 500 qubit… This goes far beyond my imagination.

If we had to build a computer (as performant as this 500 qubit quantum computer) with the technolgy we use today to build our pc’s and laptops, this computer would have the size of a large part of the universe. We would not have enough raw materials in our solar system to build it.

Experiments done todat with these kind of technology show there are still lots of computational errors. Meaning that about 80% of the capacity would be used to correct the errors. But even if only the remaining 20% of capacity could be used, the force of this computer would still be enormous,

Another feature of quantum computers that makes them unique compared to conventional computers is the phenomenon of quantum entanglement. This means that two particles have a certain bond with each other, regardless of the mutual distance. When the state of one of the particles is measured, one immediately knows the state of the second, regardless of the distance. For example: if particle one turns up, then we know that particle two is running down. Thanks to quantum superposition and quantum entanglement, it is possible for a quantum computer to perform a very large number of calculations simultaneously.

Quantum computers offer enormous computing power, but what are the applications of this brute force? An obvious application of quantum computers is to improve encryption. Encryption is now often applied by multiplying two very large prime numbers and releasing the encryption on their product. It takes an ordinary computer for centuries to decompose this product into the two original prime numbers. A quantum computer can reduce centuries to seconds here. So other methods will have to be devised to encrypt data in this way. On the other hand, quantum computers can also be used to crack classical encryption if hackers are able to lay their hands on a quantum computer.

Today we can simply invent a password or passphrase, easy to remember by our humain brain. Well when quantum computers exist you would need a library of all books in the world as password and even this could easily be cracked in a very short time.

Science would also receive a huge boost from quantum computers. For example, many experiments no longer have to be carried out properly, but they can be simulated. This can save a lot of time and money. Think, for example, of the particle accelerator in Geneva: this entire system could possibly be simulated. Or calculations about climate predictions, space research or the possibilities or limitations of genetic manipulation in crops.

A quantum computer can be used to search and analyze gigantic amounts of data. This can also boost pharmaceutical research, for example, but the enormous computing power of a quantum computer can also pave the way for AGI, artificial general intelligence.

It could maybe also affect the crypto-economy,

With traditional computers it will take many years to mine crypto’s.

Can you imagine a quantum computer mining all existing cryptos in a few seconds. The market would collapse immediately.

Do we want quantum computers?????

What is this thing that builds our dreams, yet slips away from us?