New quantum leaps – The second generation of quantum technologies
Still a hundred years after its formation quantum physics offers abundantgrounds for confusion among non-physicists – and sometimes even physicists. To understand it with our common sense proves practically impossible. The nature of the quantum objects with properties such as wave-particle dualism, superpositions of distinctly different states, measurements depending on the observer,timeless decay of the wave functions, and the spooky entanglement of distant particlesare difficult to integrate with our intuitive conceptions and the philosophical concepts of our thinking.
Thus itslack ofintuitive accessibility also leads to quantum physics being abused for all kinds of esoteric quackery: We then hear of “quantum healing”, “quantum fengshui”, “spiritual quantum resonance”, and other nonsense that esoterics like to associate with “quantum”, happily concluding that when quantum physics makes bizarre sounding statements, everything bizarrely sounding must also belong to quantum physics. And once in a while quantum serves as a substantiation of a much desired deeper interrelation between mind and matter, as in the latest book by the grandson of Thomas Mann, the psychologist and theologian Frido Mann, and his wife Christine Mann, Werner Heisenberg’s daughter and psychologist as well (“Eswerde Licht” (German), S. Fischer Publishing, 2017).
But quantum physics has long been a concrete part of our lives. Each electronical device, all digital technologies, lasers, mobile phones, satellites, televisions, radio, as well as modern chemistry and medical diagnostics are based on it. We rely on its laws every day when we get into a car (and rely on its electronics) start up the computer (which consists of integrated circuits, i.e. electronics based on quantum phenomena), listen to music (to be read CDs rely on lasers, a pure quantum phenomenon), get an X-ray or MRI, or when we communicate via our mobile phone (which is also full of microelectronics). And, last but not least, all nuclear technologyis based on it: the very first technical application of the new quantum theory was at the same time the most terrible weapon ever used, the atomic bomb. We can easily assert that quantum theory has been the most influential theory of the twentieth century.
And it could equallyshape the 21st century. For quantum physics has by no means exhausted its technological potential. On the contrary, to this day we are constantly witnessing surprises and news in its field, and at regular intervals we are experiencing technological innovations based on quantum effects. Examples are the high-temperature superconductors discovered in 1986(Nobelprize 1987), the quantum Hall effect discovered in the 1980s and 1990s(Nobelprize 1987 and 1998), LED light (Nobelprize2014), quantum cryptologydeveloped only in the last few years (Nobelprize2012), as well as new “wondermaterials” such as “graphene” (Nobelprize2010), on which a much more powerful electronics could be built uponin the future.
New quantum technologies could finally open the path for the implementation of two visions expressed by nobody less than Richard Feynman: Firstly, it should be technically possible to manipulate individual atoms (Feynman 1959). We call this development “nanotechnology”, which has already been declared as one of the most exciting future technologiesby many techno advocates. Secondly, perhaps the even more gripping vision of a so-called “quantum computer” (Feynman 1981). Such can be expected to process numerous quantum states, so-called “quantum bits” (Qubits), in parallel instead of processing information bit by bit, like classical computers. With its helpwe could problems, which so far remain too complex for the supercomputers used today in physics, biology, weather research, and elsewhere.
Quantum computers are based on the phenomenon of entanglement, the probably most bizarre phenomenon in the quantum word: a number of quantum particles can be brought into a state in which they behave as if they were coupled together by an unmeasurable band, even if they are physically far apart from each other. Each particle “knows”, so to speak, what the others are doing. They all belong to a mutual physical entity (the physicists say: a “wave function”). This results in a correlation between the particles which allows an instantaneous prediction of what the state of the one particle is after measuring the other, even if there are many miles between them. It is as if someone in the U.S. feelsinstantly what is happening to his twin in Australia.
With an ensemble of entangled qubits the physicists hope to operate simultaneously on all its possible states. While a normal computer can handle all of the bits it processes, i.e. from 0 to 1 or from 1 to 0, one after the other in many, many steps, a quantum computer can process all these steps at once. This high degree of parallelization of the operations increases the computational performance of the computer exponentially with the number of qubits, as opposed to a classical, sequentially processing computer, the computing power of which increases only linearly with the number of available computing devices.
And yet anothernew quantum technology provides for the efficient and interference-free transmission of Qubits: “quantum teleportation”, i.e. the transport of Qubits between two locations. The basis of this technology is that two quantum particles (e.g., photons) are beingentangled into a mutual quantum-physical state and subsequently spatially separated with their mutual stateleft intact. One of the particles is sent to the receiver, the other is superimposed at the transmitter with the quantum information (Qubit) to be teleported. By performing a measurement at the transmitterby the laws of quantum physics the state of the distant entangled particle is automatically and instantaneously determined without any direct interaction taking place between the two particles. The result of this measurement is then conventionally transmitted to the receiver. With this information its Qubit can then be transformed so that it has the same state as the sender Qubit. In this way, the desired (quantum) information was transferred from the transmitter to the receiver without physically transporting the particle. Next to the quantum computer with quantum teleportation we will be moving closer to a“quantum internet”.
As most of us are still concerned with the epistemological and philosophical implications of quantum physics, we should equally pay close attention to itsongoing unprecedented revolutionary technological potential. For we recognize that the understanding of the new quantum technologies opens us a view into the distance, into a future, which is very soon to come.