Press Release of October 26, 2018
Simulating the Big Bang in a laboratory setting
Similar processes to those that occurred during the birth of the Universe can also be observed in ion traps
Although we may never be able to directly replicate the events that unfolded during the formation of the Universe, the chances of simulating similar processes in a laboratory environment are nevertheless good. For instance, the creation of particles that occurred shortly after the Big Bang can be imitated in at least some respects using ion traps found in many laboratories. Ralf Schützhold from the Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Christian Fey from the University of Hamburg and Tobias Schaetz from the University of Freiburg have published an article in the scientific journal „Physical Review A“to explain how it works.
In the beginning, the world was without form and void. This statement is only partly accurate in the eyes of a theoretical physicist like Ralf Schützhold, a HZDR researcher and professor at TU Dresden. After all, the theories do explain how the Universe we know today expanded at an inconceivably fast pace during a kind of inflationary phase following the Big Bang. “But the vacuum that existed in these first tiny fractions of seconds was not completely empty, and fluctuations did exist,” says Schützhold to explain a virtually unfathomable statement of quantum field theory.
In physics, however, the word ‘vacuum’ merely signifies that no matter is present in the form of molecules, atoms or elementary particles. For example, electric or magnetic fields do exist, but they are not spread quite evenly and are a little bit stronger or weaker in some places. As soon as the inflationary phase begins, and the still miniscule Universe expands massively at an incredibly fast pace, it instantaneously – compelled by gargantuan forces – tears these fluctuations apart. During this process, the immense energies can convert into matter. This results in a pair of elementary particles that display fundamental differences with regard to one property: for instance, an electron with a negative electric charge can form together with its counterpart, known as a ‘positron’, which exhibits a positive electric charge.
Many other elementary particles originated back then. This ‘ pair-creation process’ that occurred in a fleeting moment in the earliest days of cosmic history went on to play a vital role in the subsequent fate of the Universe and our own existence – namely by creating a small irregularity, an inhomogeneity, wherever it occurred.
The temperature changed precisely at these points of irregularity. Astrophysicists are still able to identify these miniscule thermal fluctuations in the background radiation that emanates toward us from the depths of the Universe. The echo of the Big Bang continues to resonate, even after 13.8 billion years. The pair-creation process occurring in these fluctuations also ensured that particles did not spread quite evenly through space, and gravity was a little stronger in the places where larger numbers of particles accumulated. These increased concentrations therefore attracted even more matter, promoting their growth until ultimately the clusters developed into vast galaxies consisting of billions of stars. It was these galaxies and their stars that created the necessary conditions for the emergence of life as we know it here on Earth.
The celebrated Viennese physicist Erwin Schrödinger already pondered the pair-creation process in an expanding Universe. In 1933, Irène and Frédéric Joliot-Curie first observed how an electron-positron pair was created by light energy. “Unfortunately, the pair-creation process caused by the tearing apart of fluctuations during the inflationary phase of the Universe is well beyond our reach,” explains Schützhold, who recently established the Theoretical Physics Group at the HZDR.
This has led to several proposals on how to test this theory in practice. Together with Christian Fey from the University of Hamburg and Tobias Schaetz from the University of Freiburg, Ralf Schützhold has now published a new proposal in the journal Physical Review A: Tobias Schaetz could use an ion trap to replicate the pair-creation process from the inflationary phase.
An electromagnetic field in such an ion trap, for example, ensures that a magnesium ion with a positive electric charge can only move along the central axis of a cylinder. A second electromagnetic field will then fix the ion in place at a certain position on the central axis. If electromagnetic fields then trap a second magnesium ion with a positive electric charge just a few thousandth of a millimeter away, the two positive electric charges will exhibit powerful repelling forces.
Should the researchers reduce the electromagnetic field holding the ions in place, they will shoot off – propelled by the repelling forces of their identical electric charges – in opposite directions along the cylinder’s central axis. Occasionally, the escaping ions will veer off a little and also move perpendicular to this axis. So when the researchers identify this kind of oscillation in one of the ions, the laws of quantum physics stipulate that its partner, flying away in the opposite direction, must oscillate with the same energy. Similar principles apply to the pair-creation process at play when the nascent Universe was torn apart.
‘Entanglement’ is the name that theoretical physicists have given to this phenomenon – when two particles, created at the same time, are able to move far apart while still exhibiting certain properties that betray their common origins. And because this entanglement is vital for the development of extremely high-performance quantum computers, the researchers are, by using ion traps to replicate the processes that unfolded during the Big Bang, investing a little in a future technology.
Publication: Christian Fey, Tobias Schaetz, Ralf Schützhold: „Ion-trap analog of particle creation in cosmology“, Physical Review A, DOI: 10.1103/PhysRevA.98.033407
For more information:
Prof. Ralf Schützhold | Head of the Theoretical Physics Group at HZDR
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Christine Bohnet | HZDR Press Spokesperson
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