Das "blaue Buch" der Technologie-Vorfront: Quantenrechnen (Teil 2)

Today, we continue to focus on quantum computing.

In the last part, we thoroughly examined the technical principles of quantum computing, the bottlenecks in commercialization, and the latest advancements in quantum error correction.

In the following part, we mainly concentrate on the following questions:

1) What bottlenecks does classical computing currently face, and why do we need quantum computing?

2) Why should one currently focus specifically on quantum computing?

3) The six technical approaches of quantum computing

4) The latest advancements and the commercial strategies of leading companies

Understanding quantum computing requires a high level of specialized knowledge, and the content is relatively technical. Therefore, we recommend reading patiently.

(1) The bottlenecks of classical computing and the advantages of quantum computing

As manufacturing processes approach the physical limit, the upper bound of classical computing is within reach, and quantum computing comes to the forefront.

First, the computing bottleneck. The computing power of classical computing grows linearly, while quantum computing can achieve an exponential increase in computing power due to the principle of "quantum superposition".

For complex problems such as simulating drug molecules, even the most powerful supercomputer today would take billions of years to complete the calculations. Quantum computing, on the other hand, can quickly solve such problems.

The second problem of classical computing is the phenomenon of quantum tunneling.

When electronic components are miniaturized to the nanometer scale and the insulation layer is only a few atoms thick, the "tunneling" phenomenon can occur, where electrons penetrate the barrier and cause leakage currents. This leads to transistor failures, and Moore's Law hits the hard quantum barrier.

In superconducting quantum computing, electrons that form pairs (Cooper pairs) penetrate the Josephson junction through quantum tunneling, so there are no bottlenecks in this area.

The third problem is heat dissipation.

Landauer's principle states that every time 1 bit of information is erased, at least an energy of kT ln 2 is consumed, which is released in the form of heat.

Put simply: If you compare a chip to a "paper shredder", this law means that regardless of the quality of the shredder, if you want to completely destroy the paper (irreversibly), you always have to pay "electricity costs", and these costs must not be less than kT ln 2. Moreover, the shredder heats up during operation.

After Moore's Law has fallen below the 3 - nm limit, the computing density has increased significantly, and heat dissipation has become an inevitable "heat burden". It's like in an office where there are many shredders constantly running, and it gets as hot as a sauna.

To overcome the "heat barrier" and further increase computing power, there are only two options: either lower the temperature (very expensive) or switch to quantum computing.

In contrast to classical computing, the way quantum computing processes information is reversible. Entropy does not increase, and little heat is generated. Thus, the problem of heat dissipation is solved.

(2) Why should one currently focus on quantum computing?

There are two main reasons why one should currently focus on quantum computing.

First, many countries regard quantum computing as a strategic high - water mark for technological strength. In recent years, investments have been continuously increasing, and measures for export control of key devices have been issued more frequently.

Figure: Quantum computing plans of different countries, Guohai Securities, AlphaEngine

From 2019 to 2025, developed countries in Europe and America have introduced numerous investment laws and strategic plans in the field of quantum computing.

Among them, in the announcement of the priorities of federal research and development for fiscal year 2027, which was released by the White House on September 23, 2025, the United States clearly named Artificial Intelligence and Quantum Computing as the priorities of research and development budgeting for 2027 and pointed out that quantum computing has reached the critical turning point from the laboratory phase to industrial application. 2027 is an important turning point.

In the past two years, developed countries in Europe, America, and Japan have successively tightened the export control of quantum technology.

Take the dilution refrigerator as an example. In 2022, the United States decided with a ban that market leaders Bluefors and Leiden Cryogenics are no longer allowed to sell devices to China. This indirectly confirms the theory of the industry's turning point.

Figure: Export control of quantum computing in different countries, Guohai Securities, AlphaEngine

Second, industrial conglomerates are accelerating their expansion, and leading companies in quantum computing often receive huge financing.

NVIDIA invested in Quantinuum, QuEra Computing, and PsiQuantum, which belongs to Honeywell, on September 4th, 9th, and 10th, 2025, respectively. This covers the three main directions of ion traps, neutral atoms, and photons.

Take Quantinuum as an example. The company is controlled by Honeywell, and after a financing of 600 million US dollars, it has reached a company value of 1 billion US dollars.

This investment shows that NVIDIA has changed its attitude towards quantum computing from "commercialization requires decades" at the beginning of the year to active support. This also means that the quantum computing market is supported by a conglomerate and the phase of accelerated commercialization is approaching.

In addition, Bluefors announced an important order on its website on September 16, 2025. Interlune will supply 10,000 liters of Helium - 3 to Bluefors annually between 2028 and 2037, which is needed for the core devices of quantum computing, the dilution refrigerators.

Assuming that each dilution refrigerator consumes 20 - 100 liters of coolant per year, this order can meet the demand for 100 - 500 new devices per year and thus promote the industrial application of quantum computing.

(3) The technical approach of quantum computing: Photons

Currently, six main technologies are used in the global quantum computing industry: Superconductivity, Ion traps, Photons, Neutral atoms, Topology, and Spin. Each technical approach has its own advantages and disadvantages due to the different scientific nature of the computing methods, and there is still no single technology that has absolute dominance.

In terms of maturity, Superconductivity ≈ Ion traps > Photons ≈ Neutral atoms > Spin > Topology.

In the last part, we introduced the technical approaches of superconductivity and ion traps. In the following, we will analyze the remaining four.

You can find a detailed comparison of the six quantum computing approaches in the following table. The content is relatively technical, so you can save it and take a look at it at your leisure.

Figure: Comparison of the technical approaches of quantum computing, BofA, AlphaEngine

Photonic quantum computing uses photons as information carriers. The core principle is to use the rich physical degrees of freedom of photons (such as polarization, path, time, frequency, etc.) to encode quantum bits (qubits).

In contrast to approaches based on using matter to create qubits, this technology enables the precise manipulation of the quantum state of photons through linear optical elements (such as beam splitters, phase modulators) to realize quantum logic gate operations and information processing.

This method avoids the direct manipulation of matter particles and offers a unique physical approach to constructing quantum computers.

The photonic approach is characterized by an extremely long coherence time of the bits and strong resistance to environmental influences and can theoretically achieve very high fidelity.

Second, this system can operate at room temperature and does not require expensive and complicated low - temperature dilution refrigerators, which significantly reduces hardware costs and operating convenience.

Third, photons are naturally compatible with existing optical communication networks, which facilitates the construction of distributed quantum computing and the quantum Internet.

In recent years, remarkable progress has been made in photonic quantum computing both in solving certain problems and in commercial exploration.

The team of the University of Science and Technology of China has developed the photonic quantum computer prototype "Jiuzhang III", which continuously breaks the world records in solving the Gaussian - Boson sampling problem and confirms the huge potential of the photonic approach in achieving "quantum computational supremacy".

Companies like QCi are accelerating the commercial process. Their products such as the Dirac series of quantum optimization machines and the entropy quantum computing system, which are based on patented photon technology, have already been brought to the market.

In addition, companies like PsiQuantum are actively presenting their photon - based scalable computing platforms.

(4) The technical approach of quantum computing: Neutral atoms

Quantum computing with neutral atoms is a technical approach that uses the precise manipulation of individual neutral atoms by lasers.

The core principle is that optical tweezers or optical lattices are used to trap and arrange a large number of neutral atoms (such as rubidium or cesium atoms) in a vacuum to form a highly ordered atomic array.

By irradiating with lasers, certain atoms are excited to the Rydberg state. In this state, the volume of the atoms expands greatly, so that they have strong long - range interactions with other atoms.

This controllable interaction is used to construct quantum logic gates to realize the encoding and manipulation of qubits or is directly used to simulate the development of complex quantum - physical many - body systems.

The approach with neutral atoms shows enormous potential for scalability and is one of the technical approaches with the fastest increase in the number of qubits.

A notable event in 2025 was the release of the prototype of a quantum computer with neutral atoms by Atom Computing, which has an array of 1225 atoms. This was the world's first system to officially exceed the mark of 1000 qubits and thus solidified the leading position of this approach in terms of size.

Previously, the 49 - atom array of Harvard University and the 256 - atom prototype of QuEra confirmed the feasibility of this technology.

Currently, companies in China and abroad are accelerating their expansion and are committed to improving the stable control technology of atomic arrays to promote the transition of this technology from laboratory devices to industrial applications.

(5) The technical approach of quantum computing: Spin

The core of the spin - quantum computing approach is to use the proven semi -... (The original text seems incomplete here)