Quantum computer

The content of the article

• What is a quantum computer?
• Benefits
• How does qubit work?
• Quantum computing
• Superposition and Obfuscation
• Decoherence
• The probability of creating a quantum PC
• Where can quantum computers be used?

Increasing the computing power of technology is one of the main tasks of scientists and engineers. A quantum computer can solve it. The device is being developed by Google, IBM, Intel and other companies. Theoretically, a quantum PC will work 100 million times faster than usual.

What is a quantum computer?

Such a computing device does not work with bits, but with qubits. Because of this, a quantum PC is capable of simultaneously processing all possible states of an object. But in practice, supercomputers perform the same number of logical operations per minute..

Benefits

The main advantage of the new technology is quantum superiority. This is the ability of computing devices to solve tasks inaccessible to powerful supercomputers. Not all scientists support the idea of ​​creating such a PC. The main argument against this is the impossibility of verifying the correctness of the obtained solution. During calculations, the device may make a mistake by mixing up 0 and 1, and it will not be possible to identify the problem.

At the moment, the main problem in creating quantum superiority is the stability of qubits. These elements require careful handling: accidental noise or vibration leads to the loss of data that the computer was able to calculate. For stable operation of the equipment, the ambient temperature should not be more than 20 mK.

How does qubit work?

In standard computers, information is represented in binary code. The bits for storing and processing data take the values ​​0 or 1. Transistors perform mathematical operations, and the result of the binary code conversion appears on the screen.

Qubit is a unit of information storage in a quantum computer. In addition to 0 and 1, it can be in an indefinite boundary state called superposition. To get a qubit, you need to take one atom, fix and stabilize it, protecting it from extraneous radiation, bind it to another atom.

The more such elements are interconnected, the more stable the system works. To surpass a classic supercomputer, you need to bind more than 49 qubits. It is very difficult to do this: atoms, regardless of the materials used, are always unstable.

Quantum computing

The theory says that without interaction with other particles, the electron does not have unambiguous coordinates in the atomic orbit. Only during measurement does the uncertainty disappear, and the location of the particle becomes known.

The probabilistic nature of the changes allows the use of quantum computing to search unstructured databases..

Superposition and Obfuscation

Computer operation is based on two mechanical phenomena:

1. Entanglement. A phenomenon in which the state of two or more objects is interdependent. For example, in 2 photons in an entangled state, helicity will be negative and positive. The relationship will remain if you remove objects from each other in space.
2. Coherent Superposition. The simultaneous impact on the particle of alternative (mutually exclusive) conditions.

Decoherence

This is a process in which the state of a quantum system becomes uncontrollable. Decoherence occurs when many qubits depend on each other. The problem occurs when the computer interacts with radiation, cosmic rays or a magnetic field..

Different methods are used to protect computers from “rolling” to the usual computing processes. D-Wave Systems cools atoms to zero to protect them from external influences. The quantum processor is placed in protective shells, so the finished device is very bulky.

The probability of creating a quantum PC

A qubit cannot be built from several particles, and only atoms can be in the required state. By default, these multiple particles are unsettled. Chinese and Canadian scientists tried to use photon chips to develop a computer, but research was unsuccessful.

Existing types of quantum PCs:

• in semiconductor silicon crystals;
• on electrons in semiconductor quantum dots;
• in single-cavity microcavities;
• on linear optical elements;
• on ions in a one-dimensional crystal trapped in Paul.

Quantum computing involves a sequence of operations that are performed with one or more qubits, which causes changes to the entire system. The task is to choose from all its states the correct one that gives the result of the calculations. There can be as many states as possible, as close as possible to the true.

The accuracy of these calculations is almost always different from unity..

A full-fledged quantum PC requires significant advances in physics. Programming should be different from existing now. Quantum computing devices will not be able to solve problems that are beyond the power of ordinary ones, but will accelerate the solutions of those that they cope with..

The latest breakthrough was the creation of the Bristlecone processor by Google. In the spring of 2018, the company issued a statement about obtaining a 72-qubit processor, but its principles of work did not endorse. It is believed that to achieve “quantum superiority”, when a PC begins to surpass the usual, 49 qubits will be required. Google achieved the condition, but the probability of calculation error (0.6%) remained above the required.

Where can quantum computers be used?

Modern cryptography is based on the fact that it is impossible to quickly decompose a number into 40-50 characters. Classic computers will take 1-2 billion years to do this. A quantum PC will do these math calculations in 25 seconds. This means that any encryption algorithm can be cracked instantly..

Other applications of quantum computing devices:

• chemical reaction modeling;
• Artificial Intelligence;
• new drug development.

Modern quantum PCs do not know how.

Devices are capable of performing one mathematical algorithm with tremendous performance..

They are acquired by large companies, for example, to collect user statistics.