Who suggested quantum entanglement?

Entanglement - From a bizarre and long misunderstood quantum phenomenon to a key technology of the 21st century

Boundaries in today's sciences

In 1981, the famous theoretical physicist Richard Feynman gave a high-profile speech in which he developed a thought that keeps physicists and engineers in suspense to this day. He envisioned a completely new type of computer that would make today's high-performance computers look like a Commodore 64 from the early 1980s: a "quantum computer". The basis of such a computer is probably the most ominous phenomenon in the quantum world, which already gave the founding fathers of quantum theory a lot of headache: the Entanglement of quantum particles.

At that time only a bold thought by a single visionary physicist, Feynman's idea drives a whole host of physicists and engineers today, and with them billion dollar investors who already sense the next technological revolution with considerable profit potential. You all know that quantum computers, once they have grown up from their infancy, will usher in a new era in data processing. They could shape the 21st century as the development of digital circuits did in the 20th century. But it's not just the quantum computer that has made physicists' hearts beat faster for several years. Since the beginning of the 2000s a width new quantum revolution. It also already has a name: Quantum 2.0.

Without a doubt, quantum theory is the most influential theory of the 20th century. Numerous technologies based on quantum physics have become an indispensable part of everyday life today: Electronic components and integrated circuits on semiconductor chips, lasers, electron microscopes, LED light, special solid-state properties such as superconductivity, special chemical compounds or even magnetic resonance tomography. And last but not least, nuclear technologies are based on the laws of the quantum world. The very first technical application of quantum theory was the most terrible weapon ever used militarily: the atomic bomb.

All today Quantum technologies have one thing in common: They are based on properties large ensembles of quantum particles and the possibilities of their control: the control of the flow many Electrons, the targeted excitation of a huge Number of photons, the measurement of nuclear spin more massive Atoms. Examples are the tunnel effect in transistors, the coherence of photons in lasers, the spin properties of many atoms in magnetic resonance tomography or the quantum leaps in an atomic clock. Physicists have long since got used to the bizarre quantum effects associated with them, such as quantum tunnels or the wave character of matter. Because the statistical behavior of an ensemble of many quantum particles can be recorded very well with the quantum theory (the Schrödinger equation), which has now been established for 90 years, and the processes that take place in it can still be described more clearly.

With the emerging second generation of quantum technologies, on the other hand, something completely new is in the foreground: the targeted preparation, control, manipulation and subsequent selection of the states single quantum particles and their interactions with one another. Here, with the entanglement, it is precisely that property of the quantum world that so confused the early quantum theorists around Einstein Bohr and Co and whose fundamental importance the physicists only fully recognized many years after the first formulation of the quantum theory moves into the center. It describes how a limited number of quantum particles can be in a state in which they behave as if they were coupled to one another with a ghost hand, even if they are spatially far apart. Each particle then “knows”, so to speak, what the others are up to. They all belong to a common physical entity (the physicists say: a single "wave function"). There is then a correlation between the particles, which allows an instantaneous (i.e. without any time delay) prediction of which state is realized for a particle when another particle has just been measured, even if there are many kilometers between them. It is as if someone in Germany instantly felt what was happening to their twin in Australia. It would take almost 50 years for physicists to fully understand this strange phenomenon of the quantum world, and to this day it still appears to many of them as magic. The technologies made possible with it appear no less magical.

In recent years, numerous research centers for new quantum technologies have emerged around the world, and numerous state funding projects have been announced with grants amounting to billions. Examples are the Canadian Institute for Quantum Computing with around $ 300 million in start-up funding that Center for Quantum Technologies in Singapore, that Joint Quantum Institute in the US, that Engineering and Physical Sciences Research Council in the UK, and that QuTech in the Netherlands. And the Europeans have meanwhile also taken action: 3,400 scientists signed this in 2016 Quantum Manifesto, a call to promote university-industry coordination for the research and development of new quantum technologies in Europe. It says:

“Europe now needs strategic investment to lead the second quantum revolution. Building on its scientific excellence, Europe has the opportunity to create a competitive industry for long-term prosperity and security. "

Politicians finally took up this approach: The EU Commission decided to fund a flagship project for research on quantum technologies with one billion euros over the next ten years. That is a lot of money for the chronically weak households in European countries. The project focuses on four quantum technologies: communication, computing, sensors and simulations. Concrete new technologies that could result from this are:

  • Secure communication through quantum cryptology: The properties of entangled quantum particles make it possible to produce absolutely secure encryptions.
  • Quantum information transmission: This includes the possibility of transporting quantum information (qubits) over large spatial distances, which is often referred to as “quantum teleportation”. This could pave the way to a quantum internet.
  • Highly sensitive quantum sensors: entangled quantum states allow much more precise measurements of various physical variables such as time, gravitational forces or electromagnetic fields. The basis for this is the extreme sensitivity of the entanglement to external influences.
  • Reproduction of biological systems, for example in the production of an artificial leaf for energy conversion through photosynthesis, in which quantum effects play an important role
  • And finally the ultimate goal: A new era of computing with the development of a quantum computer.

Industry, too, has long since become aware of the new possibilities offered by quantum technologies. Companies such as IBM, Google and Microsoft recognize new billion-dollar businesses in them and are investing massively in research into how entangled quantum states can be exploited technologically. Examples include partnerships between Google and numerous academic research groups, the Canadian company D-Wave Systems Quantum Computing and the investments of many UK companies in the UK National Quantum Technologies Program.

Government and companies have long understood that quantum technologies 2.0 are key technologies of the 21st century. Understanding the bizarre and long-misunderstood phenomenon of entanglement finally gives us a glimpse into an apparently distant technological future, one that is certainly soon to come.

Born in 1969, I studied physics and philosophy at the University of Bonn and the École Polytechnique in Paris in the 1990s, before doing my doctorate in theoretical physics at the Max Planck Institute for the Physics of Complex Systems in Dresden, where I also did my post- Doc studies did further research in the field of nonlinear dynamics. Before that, I had also worked in the field of quantum field theories and particle physics. Meanwhile, I've been living in Switzerland for almost 20 years. For many years I have dealt with border issues in modern (as well as historical) sciences. In my books, blogs, and articles, I focus on the subjects of science, philosophy, and spirituality, especially the history of science, its relationship to spiritual traditions, and its impact on modern society. In the past I have also written on investment topics (alternative investments). My two books “Naturwissenschaft: Eine Biographie” and “Wissenschaft und Spiritualität” were published by Springer Spektrum Verlag in 2015 and 2016. I have been running my blog since 2014 at www.larsjaeger.ch.