Recently, we have been deeply analyzing the financing situation of quantum computing startups. Last year, the capital investment in this emerging industry increased by more than 65,438+000%, and the number of investors and startups in this field also increased significantly.

But some of our readers pointed out that it would be helpful to publish an introductory article on quantum computing. To this end, we wrote this article.

1) What is a quantum computer?

Quantum computers rely on quantum mechanical phenomena in nature-basically two important states of matter, called superposition states and entangled states. When these states of matter are used in calculation, it is expected to improve our ability to calculate complex data sets.

The important difference here is that quantum computers are different from traditional computers, which are binary digital electronic computers that rely on transistors.

Transistor?

Ordinary smart phones have dozens of transistors, which can be switched between 0 or 1 states, that is, on or off, so as to calculate information. Quantum computers don't use transistors (or classical bits), but quantum bits.

Quantum bit is the basic information unit in quantum computer.

The qubit may be-1 or 1, that is, it has the property of two values, which is called superposition. Therefore, it is more likely to perform the calculation immediately.

At present, the most advanced quantum computing technology on the market can use as many as 1000 qubits.

In addition, qubits can use a state called quantum entanglement; In this state, pairs or groups of quantum particles are connected together, so that each particle cannot be described independently of other particles, even if the particles are far apart (such as the two ends of the universe).

Einstein called it "ghost action at a distance", which is the theoretical basis of quantum transmission.

At this time, you may want to know, Einstein, what's in that pipe?

But don't worry. ...

For ordinary people who are not quantum physicists, it is important that quantum computers can handle a large number of computing tasks at the same time because of quantum bits and superposition entanglement, and the speed is much faster than traditional computers.

2) What is the practical application of this technology?

First, let's do a thinking experiment. Imagine a phone book, and then imagine that you want to look up a specific phone number in the phone book. A classic computer using transistors will search every line of the phone book until it finds and returns a matching number. In contrast, with qubits, quantum computers can evaluate each line and return the results at the same time, which is much faster than classical computers, so they can search the whole phone book immediately.

Therefore, this technology can be applied to industrial problems with seemingly infinite variables, and the combination of these variables constitutes a series of potential solutions. These huge variable problems are usually called optimization problems.

For example, optimize every route, airport timetable, weather data, fuel cost and passenger information for everyone in North America to get the most cost-effective solution. Classical computers usually take thousands of years to calculate the best solution to this problem. In theory, after the number of qubits per quantum computer increases-this scene has become a reality, quantum computers can complete this task in a few hours or even less.

Steve Jurveston, managing director of Draper Fisher Jurvetson, an investment company, is an early investor in D-Wave Systems, which is widely regarded as a pioneer and standard setter of quantum computing. He called the increasing capacity of quantum computers "Ross Law", which was named after Geordie Rose, chief technology officer of D-Wave.

Ross's law of quantum computing is like Moore's law in the field of semiconductor processors. Basically, the speed of quantum computers has become very fast.

D-Wave is at the forefront of commercial applications of quantum computing. But there are some details to consider. Let's listen to Steven Ulvetson.

"D-Wave has not yet made a universal quantum computer. Like an application-specific processor, it has been adjusted to handle a task-solving discrete optimization problems. This corresponds to many real-world applications, from financial and molecular modeling to machine learning, but it will not change our current personal computing tasks. In the short term, assuming that it will be applied to scientific supercomputing tasks and business optimization tasks (heuristic methods may be more than enough in these fields now), it may be hidden in the data center of Internet giants to improve image recognition and other magical task forms similar to artificial intelligence. In most cases, quantum computers will be coprocessors to accelerate classical computing clusters. "

D-Wave sells and rents quantum computers to customers like Google. It is said that the cost of these machines is between $6.5438+million and $6.5438+0.5 million, so start saving money.

The working temperature of the latest generation D-Wave 2X system is about 15 millikelvin, which is 180 times lower than that of interstellar space.

Even if the D-Wave machine doesn't work, IBM is already providing "the world's first quantum computing platform provided through IBM Cloud", aiming at enabling the public to explore quantum processing capabilities.

3) What is the relationship between network security and quantum computing?

Modern cryptography relies on a mathematical function called prime factorization. Basically, a large number is decomposed into prime numbers, and then these prime numbers are multiplied to get a large number. Classical computers are not good at this, and it takes a long time to crack the encryption code based on prime factor. But as you can guess, quantum computers are really good at this.

Governments all over the world are competing to make quantum computers that can eliminate all modern forms of passwords.

In order to develop communication to prevent hackers, the government of China recently put what is said to be the world's first quantum satellite into orbit. The name of this satellite is "Mysius". Mozi aims to develop long-distance quantum encryption communication.

This is not Mozi.

This is Mozi!

Quantum encryption refers to the concept of sending entangled optical particles (entangled photons) at a long distance by using the so-called quantum key distribution (QKD) method to ensure the security of sensitive communication.

At QKD, both the sender and the receiver measure the polarization of the entangled photons they receive by assigning 0 or 1 to each photon. This produces a quantum key that can be used to decrypt encrypted messages.

The most important point is that if quantum entangled photons are intercepted by anyone, the system will immediately show signs of interference, indicating that communication is unsafe.

In short:

Quantum computers rely on the basic principles of quantum mechanics to speed up the process of solving complex calculations. These calculations usually include seemingly uncountable variables, which are widely used, from advanced genomics to finance and other industries. In addition, quantum computers have been reshaping some aspects of network security, thanks to their ability to crack codes based on prime factorization and provide advanced encryption forms to protect sensitive communications.