Quantum computing will bring new phenomena to new standards that will change almost everything we know and believe we know about computing. Thanks to the superposition, a particular physical behavior, this new computation can solve problems that not even the conventional computer memory could solve today.
Starting at the beginning, let's compare and remember that current computing works with bits. Your computer only knows how to "read" information in two states: zero or one (on or off). For the bits we usually have only voltages: we apply 3V on a wire = 1; we apply 0.5V in the same wire = 0. And everything that is done in a computer is transcribed to this system by transistors, a kind of small boxes that can store energy and release it when necessary.
Understanding transistors is important for comparison: when a box has electricity stored we interpret a 1, and if not, a 0. We use about 6 transistors per bit and, in addition, there are circuits called logic gates, which measure the state of the boxes and save energy in new boxes depending on the states they measure. For example, the OR gate measures whether there is electricity in two boxes, and only if there is electricity in one of them does it keep electricity in another box.
Simplifying it a lot for this case, these are the physical elements that carry out the calculations that we send through programs and apps. As you can imagine, this "mechanical" system means that the speed at which a computer can process information is linear to the number of bits it has, depends on the hardware and by default has a technical limit.
The technical limit might seem like an exaggeration, make bigger computers and that's it, but it's not like that. The limit becomes evident when we think that not all the classic computers in the world are smart enough to solve optimization problems when the amount of data is too large. And at this moment in history, as a civilization, we generate immense amounts of data: climatic, population, geonomic, behavioral patterns ... We can not create useful versions or patterns of them because of the impossibility of a classic computer assimilating them all.
The difference that makes quantum technology special, and why it has such an immensely great potential, is that its bits also work with the superposition of both states: on and off. This happens because the process does not happen mechanically, but thanks to the rules of quantum physics. By applying quantum 'logic' to the computer world, problems are solved at full speed, in parallel and with a multitude of results for each variable.
The bits of quantum computing are called qubits. Like a bit, a qubit represents a basic unit of information, but a unit of quantum information, which is governed by the rules of quantum physics and therefore the qubit can be 0 or 1, or something between them. In fact, it can be 1 and 0, in parallel.
For its part, the "container" effect of transistors and logic gates are replaced by other more complicated processes, and there are several, but the idea is the same: "isolate" the qubit as it occurs within the transistor.
The ways of making a quantum computer
Quantum computers vary among themselves depending on the way they manage to isolate and drive qubits, but we are always interested in creating the same thing as in the transistor: getting them to interact only when we want, and there are several systems to achieve it
Alejandro Pozas-Kerstjens, Master in Theoretical Physics from the Perimeter Institute for Theoretical Physics in Canada and pursuing a Doctorate in Quantum Theory of Information at ICFO, said:
"There are superconducting circuits, for example. These are based on small circuits cooled to very low temperatures (-273 ºC) so that the properties are 'quantized'. That is, imagine, for example, that it can circulate through the circuit at very low temperatures 1V or 2V, but not 1.5V. This allows to know to the machine very clearly what is the 0 and what is the 1 ".
The interior of a dilution refrigerator. The gold-colored coaxial cables serve to send input and output signals from inside the refrigerator. Photo courtesy of IBM Research.
This is the technology that is most successful in companies now. For example, IBM has a quantum computer of 16 of these superconducting circuits that anyone can control from home through the web.
There are also trapped ions. In this process, the quantum computer uses ions (atoms which have been removed one or more electrons) as qubits in a certain state and keeps them trapped in laser traps, then combine them according to the calculation to be performed. Alejandro adds:
"The 0 and the 1 are identified with different distributions of the remaining electrons, or with different positions of the nuclear spin. The operations are done through lasers that modify the positions, "
Finally another well-known is the nuclear spins. These use spin states of whole molecules as qubits. The spin is a physical property of the elementary particles, but for the case that occupies us it is enough to understand that the molecules are in a certain state and the operations are implemented changing their state to a new one with magnetic resonance (yes, the same of the tests medical). "It had a lot of presence originally because the necessary conditions to do computations were not as restrictive as in other cases, but lately it has been seen that it may not be the best option."
Image: IBM Q T.J. Watson in New York. Photo by Connie Zhou for IBM.
With what has been said so far it might seem that the computer does magic on its own. Yes and no. It is not magic, they are physical laws, but it does occur "spontaneously" in the same way that magnets of opposite charge stick together or gravity causes things to fall. With quantum computing we have only noticed new norms that create new phenomenon that we can take advantage of.
One of them is that atoms and molecules, when they are not part of larger structures, are governed by rules, "different" from those we see in our everyday world. These rules are those dictated by quantum physics and, specifically, the one that uses quantum computing is superposition.
It is based on a phenomenon called particle-wave or wave-particle duality.
We talk about a behavior that is observed in subatomic particles, like the electrons of the electric charge. This phenomenon is such that the behavior of a flow of electrons, which are particles, is like that of waves under certain conditions.
A wave consists in the propagation of a disturbance of some property, involving an energy transport without transport of matter. For example, an easy wave to imagine is acoustics. A subatomic particle is one that is smaller than the atom, as an electron is, but it has a specific mass and position.
Therefore, strange as it may seem, the particles can behave like waves and vice versa. And, according to the quantum law, when this phenomenon occurs, the particle enters a superposition of states, in which it behaves as if it were in both simultaneously or at an intermediate point between the two.
"While classical objects are in one state or another (but always a certain one), the state of a quantum system can be an overlap of several possible states. For this the analogy of the coin is usually used: if the two states of a coin were to be in face or in cross, then a quantum state would be an overlap of the two"
-Alejandro Pozas-Kerstjens.
This is hard to imagine, of course. But Alejandro gave us a very good representation to understand: "Imagine that you can only know the object through its shadows."
Illustrative of the wave-particle duality. How the same phenomenon can have two different perceptions.
Sometimes in the shade you see a circle, and sometimes a rectangle. What we can say with the shadows is that, depending on how you look at it, it has the properties of a circle or a rectangle. The case of wave-particle duality is very similar. "Sometimes, light behaves like waves, for example when we make interference experiments, but other times it behaves like particles when we use lasers that send a photon per pulse."
The utility of superposition
Quantum computing tries to use the superposition of states to be able to execute more than one computation at a time. As the electrons of the qubit can be 0 and 1 at the same time, check the yes and no of each assumption in parallel, which allows us to have much faster computers. Of course, it does not guarantee more speed for all the problems but in those that can take advantage of this parallelism.
"Imagine a given program that takes two numbers and one additional bit and does the following: if the additional bit is in state 0 then the program adds the two numbers and gives you the result, and if the bit is in state 1 the program subtracts the numbers and gives you the result. If you wanted to get the addition and subtraction of two numbers, you would have to run the program twice: one with the additional bit at 0 and one with the bit at 1. On a quantum computer, since the qubit can be in an overlay of 0 and 1, the program runs the two instructions 'in parallel', and with running it once you can get a result that is the superposition of the addition and subtraction of the numbers "
-Alejandro Pozas-Kerstjens.
"While the technologies currently running on classical computers, such as Watson, can find patterns and make discoveries hidden in the vast amount of existing data, quantum computers will provide solutions to problems in which the patterns and the number of possibilities that would have to be analyzed is so huge that a classic computer could never process it. Quantum computing will provide a new wave of services, and that promises to be the next great technology that drives a new era of industrial innovation."
-IBM.
But everything is not that simple
However, using it is not so easy. Atoms and particles have their rules, and if we do not stick to them we can not control them. For example, you can not even look while the computer computes. As strange as it may seem, another of the laws that govern the quantum world is that superpositions cannot be observed or destroyed.
In addition, depending on the phenomenon that changes if other particles are nearby or simply because of the temperature is extremely difficult. Quantum properties are very fragile and even degrade over time, so many resources have to be invested in keeping quantum computers isolated from the environment. Not only have a temperature of -273 ° C, but also to keep them in vacuum conditions where an external atom cannot hit them, for example.
Image: D-Wave.
"The current idea is not that each person on the planet has its own 'quantum laptop' just because the required conditions are very restrictive, but that there is a 'limited' amount of quantum computers in places where they have the right conditions of temperature, vacuum ... etc., and people access them via Internet ."
-Alejandro Pozas-Kerstjens.
Not everyone can have a dilution refrigerator at home to keep the qubits cool, but you have to think bigger than we do typing in our living room. Quantum computers are being designed with the idea of solving problems that are currently too complex for classical computers.
One of the first and most promising areas of application will be chemistry. In a simple molecule of caffeine, the number of quantum states in molecules grows surprisingly fast, so fast that not all the conventional computing memory that scientists could build could contain it.
Other future applications could be, for example: medicines and materials (complex molecular and chemical interactions could lead to the discovery of new medicines), logistics and supply chain (calculation of optimal trajectories along global systems), financial services (modeling of financial data and investments on a global scale), artificial intelligence (automatic learning when the data flow is great), security (breaking cryptography, Shor's algorithm, for example, could do it).
Finally, to say that discovering the real utility of quantum computing is going to require many hands to experience and the potential is still to be quantified. In other words, the exponential growth of this technology is still unimaginable and who knows how far it will take us, but what is certain is that what was the limit of computing is no longer the limit, it is being revolutionized once again, and we are lucky to contemplate it.
Thanks for reading, the upvote is appreciated but the true thing I want from you is your opinion so don't forget to leave a comment with it. How much time do you believe it will take until we can buy our first quantum computer?
Always a pleasure, @michaelizer.
Source: Gizmodo - Microsoft - IBM - TechnologyReview
the d-wave puters are phenomenal, got to see one up close a couple year back, but that was only a 200 qubit system. when compared to there 2000 qubit system, that thing is massively more powerful. great post chap.
You are lucky anyway 😄. Thanks and thank you for reading.
the quantum technology is the future
Yes, indeed my friend. Thanks for reading!
Looks like I have a little bit of reading to do! That was amazing mate!
Hahaha yes it is, Thanks (after you read it) for reading lol, cheers!
Hey @michaelizer. I can barely follow many of the concepts you write about here. One thing though. I don't think time is the issue when it comes to buying a quantum computer. We sent a man to the moon in how long after we wanted to?
And that's just it. When we as a society want to do something, it usually happens very fast. So....maybe sooner than later. :)
Thanks actually true, and hope you are right about it (time). Can't wait to see how this will boost the technology advances in every area!. Thank you very much for reading, cheers
Hey man, thanks for the time to write, and the videos helped a lot too. I'm more familiar with quantum physics and the particle wave duality of light. But this made me really want to read up more on quantum computing.
Here's an interesting theoretical experiment on how quantum computing can possibly break bitcoin - https://hackernoon.com/how-i-cornered-the-bitcoin-mining-market-using-a-quantum-computer-9e5dceba9f92
Hope it provides a good read
@michaelizer You win!! You are a bigger Geek than me. I like the part about the wave particle duality. Actually that's the only part I understand.
Hahaha, I'm not such a thing. Thanks for reading it, I tried to support the content on videos to make it easier but it's kind of dense subject. Cheers!