Quantum processor: description, principle of operation

About quantum calculations, at least in theory, speak for several decades. Modern types of machines that use non-classical mechanics to process potentially unimaginable volumes of data have become a big breakthrough. According to the developers, their implementation turned out to be, perhaps, the most complex technology ever created. Quantum processors operate at levels of matter that humanity has only learned 100 years ago. The potential of such calculations is huge. Using quirky properties of quanta will speed up the calculations, so many tasks that are currently out of reach for classic computers will be resolved. And not only in the field of chemistry and materials science. Wall Street is also showing interest.

Investing in the future

CME Group invested in Vancouver company 1QB Information Technologies Inc., which develops software for quantum-type processors. According to investors, such calculations are likely to have the greatest impact on industries that work with large volumes of time-sensitive data. An example of such consumers are financial institutions. Goldman Sachs invested in D-Wave Systems, and In-Q-Tel is funded by the CIA. The first produces machines that do what is called "quantum annealing," that is, solves low-level optimization tasks with the help of a quantum processor. Intel is also investing in this technology, although it considers its implementation a matter of the future.

Why is this necessary?

The reason why quantum computing is so exciting is in their ideal combination with machine learning. Currently, this is the main application for such calculations. In part this is a consequence of the very idea of a quantum computer - the use of a physical device to find solutions. Sometimes this concept is explained on the example of the game Angry Birds. To simulate the gravity and interaction of colliding objects, the CPU of the tablet uses mathematical equations. Quantum processors put such an approach upside down. They "throw" a few birds and see what happens. The microchip records the task: they are birds, they are thrown, what is the optimal trajectory? Then, all possible solutions, or at least a very large combination of them, are tested and an answer is given. In the quantum computer, the problem is solved not by a mathematician, instead of it the laws of physics work.

How does it work?

The basic building blocks of our world are quantum mechanical. If we look at molecules, the reason why they are formed and remain stable is the interaction of their electronic orbitals. All quantum mechanical calculations are contained in each of them. Their number grows exponentially to the growth of the number of simulated electrons. For example, for 50 electrons there are 2 in the 50th power of possible variants. This is a phenomenally large number, so you can not calculate it today. The connection of information theory to physics can indicate the way to solving such problems. A 50-kbit computer can do it.

Dawn of a new era

According to Landon Downes, president and co-founder of 1QBit, a quantum processor is an opportunity to use the computing power of the subatomic world, which is of great importance for obtaining new materials or creating new drugs. There is a transition from the paradigm of discoveries to a new era of design. For example, quantum computations can be used to simulate catalysts that allow the extraction of carbon and nitrogen from the atmosphere, thereby helping to stop global warming.

At the forefront of progress

The community of developers of this technology is extremely excited and busy with active work. Teams around the world are building machines in startups, corporations, universities and government laboratories that use different approaches to the processing of quantum information. Superconducting qubit chips and qubits on trapped ions were created by researchers from the University of Maryland and the National Institute of Standards and Technology of the United States. Microsoft is developing a topological approach called Station Q, which aims to use a non-Abelian anion, the existence of which has not yet been conclusively proven.

Year of probable breakthrough

And this is only the beginning. As of the end of May 2017, the number of quantum-type processors that uniquely do something faster or better than a classic computer is zero. Such an event will establish "quantum superiority", but so far it has not happened. Although it is likely that this may happen even this year. Most insiders say that the clear favorite is the Google team led by John Martini, a professor of physics at the University of California at Santa Barbara. Its goal is to achieve computational superiority with the help of a 49-bit CPU. By the end of May 2017, the team successfully tested a 22-chip chip as an intermediate step to disassembling a classic supercomputer.

How did it all start?

The idea of using quantum mechanics for processing information has been for decades. One of the key events occurred in 1981, when IBM and MIT jointly organized a conference on computational physics. The famous physicist Richard Feynman proposed to build a quantum computer. As he said, for modeling it is necessary to use means of quantum mechanics. And this is a great task, because it does not look so simple. In a quantum processor, the principle of operation is based on several strange properties of atoms - superposition and entanglement. A particle can be in two states simultaneously. However, when measured, it will only be in one of them. And it is impossible to predict which, except from the perspective of probability theory. This effect is the basis of the thought experiment with the Schrodinger cat, which is in the box at the same time alive and dead until the observer there sneaks in. Nothing in everyday life works like this. Nevertheless, about 1 million experiments conducted since the beginning of the twentieth century show that the superposition does exist. And the next step will be figuring out how to use this concept.

Quantum processor: description of work

Classical bits can take the value 0 or 1. If you skip their line through the "logical gates" (AND, OR, NOT, etc.), you can multiply numbers, draw images, etc. Kubit can take values 0, 1 or both at the same time. If, say, 2 qubits are entangled, then this makes them completely correlated. A quantum-type processor can use logic gates. T. n. The Hadamard valve, for example, places the qubit in a state of perfect superposition. If superposition and entanglement are combined with cleverly located quantum gates, then the potential of subatomic computations begins to unfold. 2 qubits allow to examine 4 states: 00, 01, 10 and 11. The principle of the quantum processor is such that the execution of a logical operation makes it possible to work with all positions at once. And the number of available states is 2 to the power of the number of qubits. So, if we make a 50-qubit universal quantum computer, then theoretically it is possible to investigate all 1,125 quadrillion combinations simultaneously.

The Kudits

The quantum processor in Russia is seen somewhat differently. Scientists from MIPT and the Russian Quantum Center created "kudit", which are several "virtual" qubits with different "energy" levels.

Amplitudes

A quantum-type processor has the advantage that quantum mechanics is based on amplitudes. Amplitudes are similar to probability, but they can also be negative and complex numbers. So, if you need to calculate the probability of an event, you can add up the amplitudes of all possible options for their development. The idea of quantum computation is to try to adjust the interference pattern in such a way that some ways to wrong answers have a positive amplitude, and some - a negative one, and therefore they would compensate each other. And the paths leading to the correct answer would have amplitudes that are in phase with each other. The trick is that it is necessary to organize everything without knowing in advance which answer is correct. So, the exponentiality of quantum states in combination with the interference potential between positive and negative amplitudes is an advantage of calculations of this type.

Shor's algorithm

There are many tasks that the computer is not able to solve. For example, encryption. The problem is that it is not so easy to find simple multipliers of a 200-digit number. Even if the laptop is working with excellent software, then you may have to wait years to find the answer. Therefore, another algorithm in quantum computing was the algorithm published in 1994 by Peter Shore, now a professor of mathematics at MIT. His method is to find multipliers of a large number with the help of a quantum computer, which did not exist then. In fact, the algorithm performs operations that indicate areas with the correct answer. The following year, Shor discovered a method of quantum error correction. Then many realized that this is an alternative way of computing, which in some cases can be more powerful. Then came a surge of interest on the part of physicists to create qubits and logical gates between them. And now, two decades later, humanity is on the verge of creating a full-fledged quantum computer.