Quantum computers. Why them yet, although they already have?

Fifty years ago, smartphones would have seemed absolutely magical computers. Just as classical computers have been almost unimaginable to previous generations, today we are facing the birth of an entirely new type of computing: something so mystical that it can be called magic. It's quantum computers. If the word "quantum" is unfamiliar to you, you are not alone. This very cool, small, sensitive and very strange world may seem questionable system on which it is proposed to build a commercial computational machine, but that's exactly what you working on IBM , Rigetti Computing and other companies.

In January, the CES in the framework of the initiative IBM Q showed System One (see above): a dazzling, graceful and similar to the chandelier of the car, which became the first integrated universal system of quantum computing for commercial use, which could play everyone.

About the potential of quantum computers heard, probably, everyone: the properties of quantum physics offer massively parallel computing schemes, which probably will provide a huge jump in processing power and will outperform any transistor-based supercomputers, with which we can face today and tomorrow. They will revolutionize the field of chemistry, pharmaceuticals, materials science, and machine learning.

But what exactly makes quantum computers so powerful? Let's deal.

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What is a qubit?

For starters, remember how are quantum computers.

The Secret to their skill that they manipulate the qubits. Everything handles the classic computer — text, images, videos and so on — consists of long strings of zeros and ones, or bits. Inherently bit represents one state of the two: on/off or connected to the electric circuit or not. In modern computers, bits are usually represented by electric voltage or current pulse.

Quantum computers, by contrast, rely on qubits. As binary bits, qubits are the basis of computation, with one big difference: the qubits tend to be superconductors, electrons or other subatomic particles. It is not surprising that manipulation of the qubits represent complex scientific and engineering problem. IBM, for example, uses several layers of superconducting circuits that are in a controlled environment and gradually cooled to temperatures which are lower than deep space is near absolute zero.

Since the qubits live in quantum reality, they have a remarkable quantum properties.

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Superposition, entanglement and interference

If the bit to provide like a coin with an eagle (0) or tails (1), the qubits are represented by a spinning coin: in a sense, they are both eagles, and tails, and each state has a certain probability. Scientists use calibrated microwave pulses to put the qubit in a superposition; similarly, the other frequency and duration of these pulses can flip the qubit so that it was in some other state (but still in a superposition).

Due to the superposition of the individual qubit can represent much more information than the binary bit. This is partly due to the fact that when the initial input qubits can go through brute-force a huge number of possible outcomes at the same time. The final answer appears only when scientists measure the qubits — also, using microwave signals — what makes them "collapse" into a binary condition. Often scientists have to make calculations several times to verify the response.

The Confusion is even more amazing. The application of microwave pulses on a pair of qubits can confuse them so that they will always exist in the same quantum state. It allows scientists to manipulate entangled pairs of qubits, simply by changing the state of one of them, even if they are physically separated by a large distance, hence "spooky action at a distance". Due to the predictable nature of involvement, the addition of qubits exponentially increases the computational power of a quantum computer.

Interference — the last of the properties that implement quantum algorithms. Imagine rolling waves: sometimes they push each other (to act constructively), and sometimes quenched (destructive). Use interference allows scientists to control the state, reinforcing the signals that lead to the correct answer, and cancelling the ones that give incorrect answers.

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As programmed quantum computers?

The aim is to encode part of the problem in complex quantum state using the qubits, and then to manipulate that condition to bring it to some sort of solution which can be measured after the collapse of superpositions in a deterministic sequence of zeros (0) and ones (1).

Understand? Reread.

Sounds complicated, but since all the terms we have already discussed, can understand.

As in the case with classic programming, scientists are developing a languages Assembly language low-level that the machine understands it is better to go from them to the high-level languages and graphical user interfaces, it is more appropriate to the human mind. IBM Qiskit, for example, allows experimenters to create tasks and drag and drop logic elements.

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the Demon decoherence

Why quantum computers are not yet sold on every corner? In a sense, scientists are trying to buildperfect machine out of imperfect parts. Quantum computers are extremely sensitive to perturbations, noise and other environmental influences, which makes their quantum state to waver and disappear. This effect is called decoherence.

For some experts decoherence is a problem of constraining a quantum computation. Even with all the observed measures, the noise can seep into the calculations. Scientists could store quantum information for as long as it does not lose its integrity under the influence of decoherence, which limits the number of calculations that can be performed in a row.

The Delicate nature of quantum computing is also the reason that blind adding qubits to the system will not necessarily make it more powerful. Fault tolerance is carefully investigated in the field of quantum computing: logic, adding qubits can compensate for some problems, but to create a single, reliable qubit to transfer the data needed millions of error correcting qubits. And we have them today is not greater than 128. Might help smart algorithms, which are also being developed.

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quantum Simulation using quantum computers

As big data is now a hot topic, one would expect that quantum computers will better handle large data sets than classical. But it is not.

Instead, quantum computers are particularly good in modeling nature. For example, quantum computing could be used to more effectively build molecules of drugs because they basically work on the same basis as the molecules that they are trying to simulate. The calculation of the quantum state of a molecule is an incredibly complicated task which is almost impossible with our computers, but quantum computers can handle her enthusiasm.

Similarly, quantum computing can revolutionize the area of material science or information transfer. Thanks to entanglement, qubits, physical wide apart, can create a channel for the transmission of information from a scientific point of view it would be safer for our existing channels. Quantum Internet is quite feasible.

But the most interesting is this: we don't even know the variety of amazing issues that can try to resolve quantum computers. Just having a commercial quantum computer and allowing people to work with him, we could identify new interesting areas that are appropriate for this stunning new technology.

And what problem would try to solve on a quantum computer you need? Tell us .