The ability to contemplate the meaning of the world around us brings out a constant desire to deepen our knowledge and broaden our horizons This curiosity is fundamental to the development of our species and civilization From the advent of the wheel to the innovation of engines, from the cultivation of herbs to the development of modern medicine, from the abacus to computers, human history is a record of progress Our drive to explore has opened the door to new possibilities to improve our quality of life, and allow our species to thrive Throughout the centuries of scientific development, human beings have been driven by the conviction to uncover the mysteries of the universe but with each new discovery, we were confronted with new questions and challenges Today, we live in an age in which the possibility of crossing a new threshold of scientific knowledge is within arm’s reach This is the dream of quantum computerization In 1980, Russian-German mathematician Yuri Manin was the first to propose the idea of quantum computing A year later, eminent physicist Richard Feynmann presented a logical quantum computer model at the conference on physics and computerization The premise behind Feynman’s model rested in the conviction that it would be impossible to conduct the simulation of a quantum system with the use of a classic computer Feynman understood that the traditional engineering approach to the problem of computer development, would never lead to a revolution.
He based his reasoning on the laws of nature Feynman’s lectures from the last years of his scientific activities are considered by many, to be a key moment in the development of quantum computer theory. Classic computers are devices that, with the use of transistors, process information in the form of sequences of various combinations of zeroes and ones known as computer binary language. In simple terms, a transistor is a type of switch It can be turned on, which corresponds to binary 1 or it can be turned off, which corresponds to binary 0 The grouping of transistors into special circuits, which are called logic gates allows the computer to perform calculations and make decisions in accordance with a manmade computer program The computer’s processing power depends on the number of transistors used According to Moor’s law, today this power is doubling every two years As of 2014, the commercially available processor possessing the highest number of transistors is the 15-core Xeon IvyBridge-EX, with over billion transistors In the case of graphics processors, the world’s record belongs to Nvidia, which offers computer accelerators, in which the number of transistors exceeds seven billion Although this type of device is admirable and undoubtedly contributes to the development of science and technology, it does not change the fact that there are still some problems of higher rank, which could not be resolved in optimal time, even by the most advanced classic computers No conventional solutions or improvements can compare with the endless possibilities offered by the laws of quantum mechanics The quantum-mechanical states of elementary particles like transistor voltages, can be described in zeroes and ones.
Depending on the method used, we can apply various kinds of particles to the calculations Here, the state described by the zeroes and ones is the internal angular momentum of the particle known as its “spin.” Although it’s not possible to describe this particular feature feature through the use of classical mechanics, it can be likened to a magnetic bar capable of deviations When the bar is pointed up, the state can be described by value of 1; however, when it is pointing down, it can be described by the value of 0 In other words, spin up corresponds to the turned-on switch, and spin down corresponds to the turned-off switch Using this analogy, we can describe the defined quantum states with the use of binary system, much like a classic computer However, beyond this point, all similarity ends The advantage of quantum computing mainly rests in the quantum-mechanical feature, thanks which an elementary particle can be in multiple states simulataneously This type of phenomenon, called superposition, occurs before the measurement that defines the particle’s permanent state Before the measurement, when there’s no surrounding noise, the elementary particle experiences superposition, manifesting its quantum ability to occupy multiple particle states at the same time Thus, in accordance with the principles of quantum physics, a spin of exemplary particle may (in a parallel manner) indicate all directions at the same time, forcing us to describe it with zero and one simultaneously Thus, unlike the classic computer, where the basic unit of information is one bit, expressed by just one number in binary notation, in the case of quantum computing, information is expressed through a quantum bit i.e.
So called qubit, which is described by both 0 and 1 binary units simultaneously Working with qubits provides us with incredible new possibilities for the effective processing of databases, beyond what we could have ever before imagined To better illustrate the significant advantage of working with qubits, let’s consider the example of all possible combinations of 2-bit data system We have 4 possible states: zero, zero one, zero zero, one one, one A 2-bit classic computer can at the most simultaneously perform one of these four possible functions In order to check all of them, the computer would have to repeat each operation separately A 2-qubit quantum computer, due to the phenomenon of superposition, is able to analyze all of these possibilities at the same time in one operation This is due to the fact that two qubits contain information about four states, while two bits only contain information about one state Thus, a machine with “n” qubits can be in superposition of 2^n states at the same time A 4-qubit computer could analyze 16 parallel states in a single operation In comparison, a 4-bit classic computer can only analyze one state To achieve the same solution as the quantum computer, the classic computer would have to repeat this operation 16 times The advantages of quantum computing will continue to increase with the increase in data It is thus possible that a 500-qubit computer could one day analyze more data than there are atoms in the observable universe Early prototypes of quantum computers were comprised of test tubes Scientists: Neil Gershenfeld, Isaac Chuang and Mark Kubiniec made use of the phenomenon of nuclear magnetic resonance to create the first quantum computer model The model was comprised of a test tube,which contained chloroform particles The apparatus was placed in a constant magnetic field, that helped the scientists to focus on the interactions between the spins of hydrogen and carbon, which acted as a logic gate The programming was conducted with the use of radio impulses of particular frequencies, which resulted in the variation of spins The test-tube computer model successfully found the element in the four-element data set Although these early experiments were successful, researchers from University of New Mexico claim that these early computer models were nothing more than classic simulations of quantum computing The possibility of actually developing such a system for practical applications is not readily conceivable To develop a fully efficient quantum computer, certain requirements must be fulfilled One of the most important is to create appropriate conditions, under which it would be possible to manipulate qubits while allowing them to maintain their unique properties It is a very difficult task that requires great precision and special equipment, but doing so would give way to a plentitude of possibilities offered by the fundamental laws of nature However, in a macro world such as ours there are many obstacles to the development of quantum systems One of the biggest problems faced by scientists working to develop quantum computers is the issue of decoherence Each elementary particle is subject to wave-particle duality, meaning that sometimes it behaves like a particle, and other times, it behaves like a wave.
The particle behaving like a wave is subject to a phenomenon known as “unitary evolution,” which is described by Schrödinger’s equation It’s a state in which noise from the surroundings (i.e. decoherence related to, among others, thermal energy) is not sufficiently large enough to trigger the leakage of very susceptible quantum information Such evolution of entanglement and mutual decoherence may be analyzed and controlled in time, which allows for the processing of information in a completely new way Additionally, it is essential that the qubits remain in the state of quantum entanglement only with each other, forming a coherent system, in which the exchange of quantum information may occur between them Unfortunately, our surroundings are comprised of elementary particles, which only serve to disrupt the precision of quantum processing Such uncontrolled entanglement of qubits with the surroundings outside the system could lead to a leakage of important information Consequently, it’s essential to isolate and cool the quantum computer processor, where the calculations take place The cooling of the processor to extremely low temperatures, near absolute zero, helps to calm the qubits, by propelling them into a state of extremely low energy levels, and as a result, makes them easier to control Cooling is also important due to the fact that some of the superconducting materials used in the construction of quantum processors and their unique properties can only be used at very low temperatures Aside from nuclear magnetic resonance, other solutions and phenomena may be used to create a quantum computer such as: polarization of light, Bose-Einstein codensate, quantum dots ion traps or fullerenes Regardless of the method used, the goal is to achieve the capability to control quantum states in such way that it would be possible to program the computer, perform the calculations, and finally, read the desired result In 2012, scientists from the University of New South Wales created the first single atom transistor made of silicon In light of the many positive and interesting results of the research on the control of quantum states, the team of Australian researchers, led by Michelle Simmons, has garnered worldwide recognition If you look at it, people want to get computers that work faster and faster They want to spend less time surfing the Internet They want to solve problems that they just can’t do They want more graphics So, whatever is happening internationally in the world of silicon chips they are getting smaller every year that’s actually driven by the market the market wants things smaller, they want things faster It has been theoretically predicted many years ago if you could make a computer that work in a quantum regime you would be able to solve problems you just can’t do with classical computers First of all, you got to create the single atom device, and the technology to do that just didn’t exist 10 years ago How do you put a single atom in silicon How do you encapsulate it, so it’s in a crystalline environment so it’s still within the semiconductor host material and then how do you actually put wires down to connect to that single atom so that you could control that single atom To manipulate atoms you have to be inside a microscope such as the one behind me and that works in a ultra-high vacuum environment it’s a big piece of stainless steel with no air inside it’s a vacuum in that vacuum environment you can manipulate the atoms and that literally uses a very fine metal tip and that metal tip, you actually move it across the surface of a crystal so you see the atoms on the surface, and you literally move that metal tip across and as it goes over the atom it deflects what you are doing is you measuring a current and keeping it constant and as it defllects you are measuring the small changing current as it goes up and high And so, wth such a technique you’ve been able to image the atoms on the surface and then by applying pulse voltages to the tip you can actually change the chemistry of the surface and typically what we do on the silicone surface we take a silicone surface nice and clean, and we put down one layer of hydrogen atoms it just literally has a silicon hydrogen bond and then wth th STM technique, we can apply a voltage to the tip just above that silicon hydrogen bond and literally release one hydrgen atom from the surface leaving a dangling bond and that is very reactive and to that reactive dangling bond we bring in phosphine gas which will only stick to that dangling bond, and nowhere else on the surface it’s in such a way that we can bring that phosphorus and put it exactly in one atomic lattice place where we wanted once we’ve done that, we encapsulate with silicon over the top of that and by encapsulating it with silicon we surround it with silicon atoms so it’s sitting one phosphorus atom and silicon all the way around it so, it’s nice clean environment for that phosphorus atom This is a scanning tunneling microscope, on the right hand side this is connected under ultra-high vacuum with a piece of stainless steel to a molecular beam epitaxy system I guess, it’s a very few people, actually several groups had tried to connect these two technologies before and they found that the vibrations from the crystal growth side actually destroy the imaging that you get with the STM It’s actually very difficult to bring those two technologies together So, we actually literally had to work with lots of engineers with both the company’s and independent acoustic engineers to bring two technologies together it’ a very expensive system, it costs about 3 mln $ It was one of those turning points certainly in my career because if they didn’t come together and work, that probably would be the end of me We built the whole crystal structure inside the vacuum, one atomic layer by a time and then we take it out and then we have to find it and that was one of the first challenges we had How do we find that single phosphorus atom What we’ve done is over the last 5-10 years we’ve developed techniques and patented them we were making markers on the surface that are visible all the way through when you put in vacuum, and you take it out and making sure that the phosphorus atom is registered with respect to that marker But how do you connect to the outside world? The connections you’ve got to make, they’ve got to be as small as you can make them When you…
Literally try to adress that atom you just adressing the atom, and not all the atoms around it So, when you take it out, you can see the marker You put down your metal electrode on the surface that control the sipn states, electron states of the phosphorus atoms and then you apply voltages to those on the surface The recording of information starts with the introduction of atoms into the lowest energy state, through cooling of the device Phosphorus atoms have electrons, which also have a spin Let’s imagine the electron as a pendulum When it is in its lowest position, it has the lowest amount of energy but when we start to push it lightly, it gains energy Such pushes can be performed with the use of microwave radiation which propels the electron into an increasingly higher energy state When the pendulum reaches its culminating point, the electron may detach itself from the atom The single electron transistor is a very sensitive measurer of the flow of electric charge thanks to which we can examine the flow of a single electron This type of electron detachment from the atom is equivalent to a particular direction of spin corresponding to the number “1” in binary notation In other words, our capacity to measure the flow of a charge enables us to learn which spin had a single electron So, what we see here is first a spin up electron tunneling in and after a spin down electron tunneling back out again To me as a physicist this is actually the most amazing thing that I’ve done in my scientific career To be able to observe something that I would never be able to see with a bare eye we get it visible with these extremely sensitive measurements to look at one single electron spin instead of things that you can touch with your bare hands If the Australian team is successful in increasing the number of qubits such that all of them are appropriately isolated from the environment, while in a state of quantum entanglement, then it will open up a new door in the world of quantum computing In addition to the universal model based on logic gates, which the Australian scientists have worked on there are many others.
One such model is the adiabatic quantum computer. The adiabatic quantum computer was built by the company D-wave which was the first in the world to put such advanced equipment on the commercial market This company, founded by Vern Brownell and Geordie Rose began in the Physics and Astronomy Department of University of British Columbia in Canada but it later became an independent entity. The idea of building a quantum computer system was born out of the scientists’ experiments with superconducting materials The basic elements of D-wave’s computer processors are called “Squids” (Superconducting Quantum Interference Devices) which are some of the most sensitive devices used to measure the intensity of magnetic field In simple words, SQUID is a certain kind of superconducting ring divided by what is known as the Josephson junction The superconducting materials that make up these devices have certain unique properties, thanks to which, at very low temperatures, nearing absolute zero, quantum uniqueness takes precedence over the classic principles of physics that we are accustomed to For example, in the cooled superconductor, or Squid, the phenomenon of electrical resistance does not occur at all, and due to a phenomenon known as the Meissner effect, some objects can even levitate.
Unlike the single-atom transistor, here, the form of qubit is the direction of movement of many united electrons, which, as a result of the low temperature and superconducting properties, may be considered equivalent to what, in the previous model, was the direction of the spin In other words, here, zeroes and ones describe the direction of flow of electrical current through the superconducting rings The clockwise-flowing current corresponds to ”0”, while the counterclockwise-flowing current corresponds to ”1” The entire computerization process in this type of model is based on the probabilistic method of what’s known as quantum annealing Quantum annealing consists of finding the optimal values among all possible solutions The name of this method is derived from annealing in metallurgy, which is a technique of controlling the temperature of the cooled metal alloy Slow cooling allows for the formation of ordered crystalline structures In quantum annealing, the magnetic field is the equivalent of temperature For instance, to find the lowest valley during a hike in mountainous terrain, we would have to trek across the terrain to finally arrive at the right place Quantum mechanics reduces this search Quantum tunneling is a unique phenomenon, which allows the particles of the micro-world to cross the walls, contrary to the law of conservation of energy Thanks to quantum tunneling, the electron searching for the lowest point in the given terrain would not have to cross it up and down, because it would have the ability to penetrate through those intuitive mountains, allowing for much more efficient searches If the controlled variations in the magnetic field, during this walk of electrons, are sufficiently slow, then, once the magnetic field is turned off, we should be able to arrive at the correct solution, which in this analogy would be the lowest point of the area D-wave’s first client was an American armaments company called Lockheed Martin, which at the end of 2010, decided to purchase a 128-qubit D-wave One computer for 10 million dollars In 2013, with the cooperation of Google, NASA and USRA, D-wave created a 512-qubit D-wave Two computer for an artificial intelligence laboratory Researchers in this laboratory are using the D-wave Two computer to facilitate them in their work on in areas such as: the improvement of voiceactivation device technology, development of new drugs, climate change modeling, optimization of traffic control, development of robotics, and machine navigation and shape recognition However, within the scientific community, there is a continuous and lively debate over the question of whether the computers manufactured by this Canadian company can actually be considered as fully quantum One of the basic allegations posed by the critics is the possible absence of quantum entanglement occurring between the qubits comprising the D-wave processors However, according to most recent published scientific studies, the computer definition used by D-wave is correct Only time will tell whether this information is definitive In order to take advantage of all that is offered by the fundamental laws of nature,offered by the fundamental laws of nature, we need software and algorithms, which are just as necessary as basic construction elements Creating the algorithms however, is a very difficult task, as it requires that we take into account the counterintuitive laws of quantum mechanics Nevertheless, there are many people who have risen to the challenge Peter Shor and Lov Grover are the creators of some of the most well-known quantum algorithms Most notably, since its creation, Shor’s algorithm has generated a great deal of discussion among the scientific community, as it could be used to break the modern encryption keys such as RSA If there were a quantum computer capable of efficiently using Shor’s algorithm the use of encryption, to secure bank accounts and other operations, and the accompanying difficulty of mass numerical division would cease to exist Classic computers don’t handle this type of difficulties very well, so we can sleep peacefully, without worrying that our bank account will be cleaned out by a quantum hacker Another significant algorithm is Grover’s algorithm, which was devised to sort through information in unordered databases Imagine searching through a phone book with a random assortment of names In order to find a given telephone number, you would have to search through each and every listing, which would undoubtedly be cumbersome and time-consuming However, by applying Grover’s algorithm to a quantum computer, you could retrieve the desired name in only a few seconds It should be noted however, that a single outcome obtained from such calculations is only a probable solution The more times the computer performs the calculations, the more likely it is to find the proper solution to the problem Quantum computers are devices mainly designed to solve complex problems, which require us to deal with very large amounts of data These types of machines will soon find their practical application in research laboratories, instead of computer games The role of a quantum computer is to provide assistance in capturing what is beyond the boundary imposed by time and energy needs Perhaps, in the not so distant future, we will be able to climb up the ladder to a new rung of possibilities, such as the creation of new drugs, breakthroughs in research on climate change, and the development of new technological devices It is the hope that these new discoveries will provide us with a deeper understanding of the structure of the reality that surrounds us And all of this thanks to the laws of nature and the desire to explore, which defines humanity