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Technical Applications

In our search for applications of quantum mechanics, we could take the easy way out. For instance, the tunneling effect enables transistors, which are found in every laptop, phone, and smartwatch, to function. We could easily list many more applications, such as lasers and superconducting components, and quickly realize that modern technology would not work without quantum mechanics. The utilization of quantum mechanics that has resulted in the devices we are familiar with today originated 100 years ago with the formulation of quantum mechanics. This is called the first quantum revolution.

However, in practice, the truly fascinating properties of quantum states—entanglement and superposition—are not actively controlled, but rather utilized passively. This does not take full advantage of the possibilities of quantum mechanics.

Nevertheless, the theory of quantum mechanics suggests that it is possible to build quantum computers that can perform calculations much faster than the “classical” computers we are familiar with for very specific applications. These quantum computers could communicate via a quantum internet and use extremely secure encryption systems against eavesdropping attacks thanks to quantum effects. Fast quantum computers and secure quantum communication are currently a future scenario being researched and developed at full speed. Over the past ten years, major IT companies have established their own development departments and made significant investments, creating a diverse landscape of start-ups offering various quantum technologies.

Furthermore, the properties of quantum mechanical systems, such as superposition and entanglement, are utilized in sensors for measuring physical quantities with extreme precision, a field known as quantum sensing.

This new momentum in the technical utilization of quantum mechanics has its origins in the formulation of the principles of quantum communication in the 1960s and is known as the second quantum revolution. We are right in the middle of this exciting process!

Superconducting train

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Supraleitende Eisenbahn

 

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More on: Superconductors

Superconductors are materials that change their physical properties at low temperatures: In the superconducting state, below a specific temperature for the material - the transition temperature - the electrical resistance disappears. This is a quantum mechanical effect.

Superconductivity was discovered in 1911 by Heike Kamerlingh Onnes using mercury, which becomes superconducting at 4.2 K (-269oC). Many metals are superconducting but normally the transition temperature is below -200oC, which means that the materials must be cooled with liquid helium to become superconducting.

Superconductors and magnetic fields: In the superconducting state, the Meissner-Ochsenfeld effect occurs, i.e. an external magnetic field is completely displaced inside the material. In an external magnetic field, magnetic fields are built up on the surface by currents that compensate for the magnetic field. A magnetic field that is not too strong only penetrates about 100 nm deep into the material; this thin layer carries the shielding currents. In a so-called “hard” superconductor, an external magnetic field partially penetrates the superconductor, which results in the superconductor hovering in a stable position above a strong magnet.

Superconducting materials are primarily used to generate extremely strong magnetic fields, for example in nuclear fusion facilities, at the LHC particle accelerator at CERN, where superconducting magnets guide and focus the beams, or in medicine. Here, strong magnetic fields are used in magnetic resonance imaging (MRI) for precise medical imaging. Other fields of application include quantum computers and superconducting cables for loss-free power transmission.

More on: Quantum Technologies

Quantum technology is an exciting and rapidly advancing field of research and development. It employs the principles of quantum mechanics, such as superposition, entanglement and quantum tunnelling, to create technologies that far surpass classical systems in terms of performance. Examples include:

  •  Quantum computing, where quantum bits (qubits) can exist in multiple states simultaneously (superposition) and be entangled with each other. This allows for extremely fast calculations of complex problems in areas such as cryptography, materials science and optimisation.
  • Quantum communication: Secure communication can be achieved through quantum cryptography. Thanks to quantum entanglement, any manipulation can be detected immediately.
  • Quantum sensors are extremely precise instruments that use quantum effects to detect minimal changes in magnetic fields, gravitational fields, and time measurements. These sensors are used in medical technology to detect the slightest changes in magnetic fields, for example, with the help of extremely sensitive quantum sensors (SQUIDs). These can be used to detect heart disease or measure brain activity in real time.
  • Quantum materials are materials whose macroscopic properties depend directly on quantum phenomena; examples include superconductors and topological insulators.

The current state of quantum computers is as follows: There are already many commercial products available, such as the quantum computers produced by the Canadian company D-Wave and IBM, which cost around CHF 10 million. These are mainly used for testing purposes, as they are not yet advanced enough to outperform conventional computers. Meanwhile, research is ongoing into which technology platform is best suited to quantum computing. It is not yet clear what the 'silicon of quantum computing' will be. However, when that moment arrives, all stakeholders will want to be as prepared as possible. Software providers are therefore developing quantum programming languages (Microsoft Q#, Google Cirq and IBM Qiskit), and banks are exploring the potential of quantum finance.  In short, current developments in quantum technology are characterised by great uncertainty, expectation and possibility. These could lead to the most significant technological innovations since the invention of classical computers.

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