( Probably one of the most confusing twenty-five -minute to thirty-minute read I have ever written) 

The computing power that we have available to us at our fingertips is astonishing but even with the most powerful supercomputers on the planet, some problems are still way beyond our reach and there are still some problems out there that would take longer than the universe has existed to solve.

In the past, we believed all computers fundamentally did the same thing—just maybe one a bit faster than another but when it comes to Quantum Computers do any of us know what we are talking about. 

There are loads of attempts to explain Quantum computing in layman terms but the truth is that physicists are themselves in general agreement that no one really understands quantum mechanics which is the basis for a Quantum Computer.


Because Quantum mechanics can be used to describe many physical systems.

However, there is a common set of core principles that all of these physical systems obey.

So as quantum computers promise to truly transform our world here is another attempt to get quantum computing into an understandable language. 

Just what is a Quantum Computer?

It’s like having a big airport with lots of baggage terminals, and you are looking for a lost suitcase on one of them. You employ the help of some friends to search each of the terminal one by one before you find the suitcase. A Quantum computer will search all the terminals at the same time, and only the terminal on which it is found exists after you look at it.

Weird, Yes, but this is where it gets really complicated.

The goal in quantum computing is to choreograph things so that some paths leading to a wrong answer have positive amplitudes and others have negative amplitudes, so, on the whole, they cancel out and the wrong answer is not observed.

Any the wiser? No!

Here are the dudes that contributed to its discovery, not the suitcase but the quantum Mathematics.   

They all puzzles about matter and light. Coming to the conclusion that was solved by postulating that atoms and particles behave differently from macroscopic objects. Eventually, this led to the theory of quantum mechanics, which explains all of those differences, using a small number of basic principles.

One has to think of quantum mechanics as a generalization of probability theory in which probabilities can be negative.

The idea of quantum computing, however, is to use physics to do the math. For example, to devise quantum algorithms such that all the possible ways to get to the wrong answer interfere with themselves and cancel each other out, while leaving only the possibility of getting to the right answer.

Still none the wiser.

I would love to ask them why should Nature have been quantum-mechanical?

In computers, we can stuff the laws of nature into it mathematically and create the world. Other words if a computer has a sequence of thirty 0s and 1s, it has about one billion of possible values.

However, a classical computer can only be in one of these one billion states at the same time. A quantum computer can be in a quantum combination of all of those states, called superposition. This allows it to perform one billion or more copies of computation at the same time.

But how do we access these billion results?

Experiments in quantum physics are now creating artificial physical systems that obey the laws of quantum mechanics but do not exist in nature under normal conditions.

In order to fully understand the quantum world, you have to develop a new realm of mathematics.

We have little daily experience dealing with elementary particles.

The bizarre world of quantum theory — where things can seem to be in two places at the same time and are subject to the laws of probability — not only represents a more fundamental description of nature than what preceded it, it also provides a rich context for modern mathematics.

If all mathematics disappeared today, physics would be set back exactly one week,” to which a mathematician had the clever riposte: “This was the week that God created the world.”

In the quantum world, everything that can happen does happen and all are considering everything at once.

Every quantum particle, such as an electron, can be considered both as a particle and as a wave offering different perspectives on the same physical phenomenon that underlies quantum theory and, ultimately, reality.

Another words you can look at the world with a mathematical eye or with a complementary physical eye, but don’t dare to open both because the world, is not as certain as our everyday experience of has us believe.

And of course, there is no need for me to tell you that nobody has ever directly seen a single particle in several places at once.

Somehow, measurement causes reality to “snap”. Reality splits into different branches at the point of measurement. In each branch an observer sees one of the possible outcomes. One can never, ever measure both the position and the momentum of a quantum object.

Time and energy are another pair that can’t be measured simultaneously so in real life, we cannot measure states. 

No I am not making this up. So don’t doubt. Just carry on reading.

A quantum computer encodes information into quantum states and computes by performing quantum operations on it. It is using trapped ions. An ion is an atom that has lost one or more of its electrons. An ion trap is a system consisting of electric and magnetic fields, which can capture ions and keep them at locations. Using an ion trap, one can arrange several ions in a line, at regular intervals the more trapped ions the better.

The computation is then performed by using light to manipulate the states of ions. 

This is known as quantum parallelism. The result of this process is a quantum state.

It is not a classical state (A “state”, in general, is the collection of numbers needed to completely describe the physics you are interested in) in the sense that we could ever observe the switch in the “on and off” state, it is a quantum state that exists in an abstract space called Hilbert space. (A space with more than three dimensions.)

Still in a state of confusion. Don’t blame you. It’s wholly abstract.

How about a particle in some state that may interact with another particle in some state…

Now imagine you can make a bit (the smallest unit of data in a computer) that can be in the zero and the one state at the same time. That’s called a quantum bit or qubit. 

The simplest example in nature would be just a single electron. It has a magnetic dipole called spin, which is like the needle of a compass but because it’s a quantum needle, it can be pointing up and down at the same time.

By this time your brain might be in a vat. Mine is. 

They a bit or qubit. must have some form of existence because the Quantum theory is a theory about real objects in nature, what else should a physical theory be about?

The quantum state appears to be something intrinsically holistic ie emphasizing the importance of the whole rather than analysis or separation into parts. 

Every state of a system is represented by a ray (or vector) in Quantum entanglement is a physical phenomenon that occurs when pairs or groups of particles are generated or interact in ways such that the quantum state of each particle cannot be described independently of the others, even when the particles are separated by a large distance-instead, a quantum state must be described for the system as a whole.

If we measured a quantum state, we would get just one of the results. All of the other 999,999,999 results would disappear.

So Quantum computing takes advantage of the strange ability of subatomic particles to exist in more than one state at any time.

The goal of quantum mechanics was to understand the laws of nature according to how quantum systems function.

The new goal is to manipulate and control quantum systems so that they behave in a prescribed way.

For a parallel computer, we need to have one billion different processors. In a quantum computer, all one billion computations will be running on the same hardware.

But in order to know anything about anything, some detection scheme needs to happen.

To solve this problem, one uses the second effect, quantum interference. Quantum interference is used to combine the results into something that is both meaningful and can be measured according to the laws of quantum mechanics.

Sorry, we back to Quantum Mechanics which is based on numbers called amplitudes, which can be positive or negative or even complex numbers. In quantum mechanics, the wave function is complex-valued, and the square of the absolute value yields a probability.

All of these achievements of quantum computing are based on the same effects of quantum mechanics. On a high level, these are known as quantum parallelism and quantum interference.

I have no idea what it means for a probability to be an amplitude.

Amplitudes alone are not enough to fully describe a system.

Can someone give me some kind of intuitive explanation of this concept?

Why does probability have to act like a probability?

Why should amplitudes have complex numbers?

Surely a wave is a defined frequency and phase.

Anyway, we are left with the question why do we need it?

We know that they will be faster for many computational tasks, from modelling nature to searching large amounts of data.

With a quantum computer, it is hoped to find a more efficient way to produce artificial fertilizer, having a direct impact on food production around the world, and it is hoped to help with combating global warming by learning how to efficiently extract carbon dioxide from the environment.

They will be used to conduct virtual experiments. For example, quantum chemistry re molecular simulation.

As far as it is possible to know they could be the final step in intertwining us with AI.

(The current record distance for measuring entangled particles is 1,200 kilometres or about 745.6 miles. Entanglement means that the whole quantum system is greater than the sum of its parts.) Entanglement is a fascinating property of quantum mechanics that’s completely counter-intuitive.

I think there are many more applications and, perhaps, the most important ones are still waiting to be discovered.

But there is a line that must not be crossed and that is there use intentionally or accidentally to kill us, i.e. a Quantum magical drone armed with AI and an electro-magnetic pulse would have the potency to annihilate us all.    

Now that your brain is fried I leave you with this thought.  

Our own system is barley understood to this day.

This thing on our shoulders is constantly working out problems even as we work on making breakfast. You are creating a program that thinks and is separate from you, within you.  You are a Quantum Computer. 

We know that our brains receive their signals in symbolic form. The method of transmission and the network of transmission are a mix of electrochemical reactions that are harmonic to our network.

Quantum computing will potentially mark one of the tech world’s biggest revolutions, harnessing the quirks of quantum mechanics to speed up machine computation exponentially but as computers, they have a long ways to go to catch up with human thought and common sense. Considerably more work is needed before we can reach the long-dreamt-of moment when machine intelligence matches the human variety.

This is the huge problem on the horizon, endowing AI programs with common sense.

Even little kids has it, but no deep learning program does. It will take more than a hybrid computer to show that humankind of understanding.

Quantum or not it will still have a capacity for things the human mind can do easily, like abstraction or inference that make it possible for us to “understand” from very little information, or instantly apply insight to another set of circumstances.

A “quantum leap”quantum-ibm-1

The day may come when intelligible sentences combining quantum mathematics with brain function/consciousness/mental functions can be crafted, till that day our free will still come from quantum indeterminacy, not complex hybrid quantum algorithm yet to be devised.

The expectation is that one day when the computer technology industry achieves so-called “quantum superiority” and deliver real commercial benefits we will be best to let the idiot be an idiot. 

Finally, it has just been reported by the financial times that Google’s quantum computer was able to solve a calculation – proving the randomness of numbers produced by a random number generator- in 3 minutes and 20 seconds that would take the worlds fastest traditional supercomputer around 10,000 years.

Sleep tight.  


“As far as the laws of mathematics refer to reality, they are not certain; and as far as they are certain, they do not refer to reality.”

All human comments appreciated. All like clicks and abuse chucked in the bin.