Technology Briefly Explained The Development of Quantum Computing

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Discover the quantum computer—with qubits operating in superposition and entanglement, they offer astonishing computational power and could shape the future of computing technology.

If one wants to describe a quantum computer and its capabilities, it sometimes sounds like describing magic—because in the quantum realm, our understanding of physics no longer applies. To at least begin to understand quantum computers, it's useful to first look at classical computers: A computer is based on tiny electronic circuits embedded in microchips, or so-called integrated circuits (ICs). These contain active and passive components, wiring, and transistors—tiny electronic switches and the smallest functional unit in a computer.

Why Transistors Can't Get Smaller

A transistor functions like a switch: it represents a state using voltage potentials—either 0 or 1, the smallest binary unit in a computer, known as a bit. Transistors are interconnected to create logic gates. These logic gates, when linked together, can perform basic computational and storage operations. These simple circuits are sufficient to execute highly complex applications, as modern computers are capable of today.

To achieve more performance, computer technology has been miniaturized for decades. Transistors today are unimaginably small, at just 10 nanometers—allowing 18 billion transistors to fit on a chip measuring two by two centimeters.

But now a physical limit in miniaturization has been reached. On the one hand, conventional manufacturing methods using ultraviolet light are no longer sufficient to produce even smaller transistors. On the other hand, transistors that are only a few atoms in size exhibit strange physical phenomena that, according to our understanding, should not be possible: although a physical barrier within the transistor can prevent electrons from progressing, at such small scales, they manage to pass through the barrier. This tunneling effect, also known as the quantum mechanical effect, prevents classical computers from being further miniaturized.

However, researchers aim to leverage this effect to develop so-called quantum computers.

How Does A Quantum Computer Work?

In quantum computers, the smallest unit of information is not the bit but the quantum bit, or qubit for short. A classical bit has a clearly defined state of 1 or 0. A qubit also recognizes the states 1 and 0, but unlike a conventional bit, the qubit simultaneously occupies both states and is not limited to just one state. This property is called superposition.

And here's where it gets interesting: The state of superposition remains as long as the qubit is unobserved. However, the moment the state of the qubits is measured, it assumes a clearly defined state—1 or 0—with a certain probability.

The computing power of quantum computers becomes apparent here as well: in a classical computer, one bit can represent four different combinations (00, 11, 10, 01), out of which one is selected—but a qubit can use all four combinations simultaneously. Additionally, due to their superposition, qubits can perform parallel computations—and each additional qubit exponentially multiplies this capability.

A second remarkable property of quantum computers is entanglement. Two qubits that are entangled have a connection between them—regardless of their distance. Even over thousands of kilometers, the qubit assumes the state of its entangled counterpart, entirely without any time delay.

How Does A Quantum Computer Calculate?

As previously mentioned, classical computers use logic gates for calculations. In quantum computers, so-called quantum gates are used, and although these gates differ significantly, the same computational operations can be performed—with the groundbreaking difference that a quantum computer can perform these calculations simultaneously.

What A Quantum Computer Can Do

Encryption: This capability could indeed pose a threat to our IT security, especially to current cryptographic encryption methods. Prime factorization is a common encryption method and is considered highly secure. In this method, a number is created by multiplying several prime numbers. Restoring the original prime numbers would take current computers 100,000 years. However, since quantum computers can perform calculations in parallel, they could crack these encryptions within minutes using the so-called Shor algorithm. This would affect encryptions used by e-commerce platforms, cloud services, e-banking, IoT systems, and everything transmitted securely over the Internet.

The good news, however, is that quantum computers also enable a new type of encryption: quantum cryptography. Nonetheless, security experts are already warning to consider potential quantum computers in the future—especially for sensitive data stored over decades, such as banking data, as there is a risk that old encryption could quickly be cracked with the advent of quantum computers.

Databases: Another application of quantum computers is searching massive databases using the Grover algorithm. While a classical computer searches a database entry by entry, a quantum computer can, thanks to superposition, scan the entries significantly faster.

Simulations: Highly complex simulations, such as those of quantum mechanics itself or intricate molecular structures, can also benefit from quantum technology, as conventional computers reach their limits here.

What is the Current State of Quantum Computers?

Currently, both research institutions and companies are building quantum computers, utilizing completely different architectures. Google and IBM, for instance, are independently building quantum computers based on superconducting stripline resonators. A qubit in this case is an electron cloud within a microwave oscillator. This is cooled down to 15 millikelvin, near absolute zero. A Josephson junction enables quantum tunneling, and by adjusting the oscillator frequency, the qubits can be entangled, and quantum gates can be applied.

Last year, Google made headlines by presenting their first quantum computer, which performed a calculation in minutes that would otherwise take classical computers 10,000 years. This calculation was carried out with 53 qubits. As the next step, Google plans to realize a chip with 1,000 qubits—however, the number of qubits alone is not decisive for computational power; the qubits must also be of high quality to ensure a low error rate.

How important quantum computers will become for our future is currently difficult to predict. Research on quantum computers is still in its infancy. It is unlikely that they will replace our classical computers, but the direction of development and what the next quantum leap—ironically a Janus word, as a physical quantum leap is something extremely small—will be, remains uncertain.

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