![]() ![]() This is also true for the Unruh effect: If the original version cannot be demonstrated for practical rea-sons, then another quantum system can be created and examined in order to see the effect there. "In contrast, analog black holes can be readily produced right here in the lab." Cisco Gooding from the Black Hole laboratory emphasizes. "Simulating one system with another has been especially useful for understanding black holes, since real black holes are effectively inaccessible," Dr. "This means that you can often learn something important about a particular quantum system by studying a different quantum system." One can use the same formulas to explain completely different quantum systems," says Jörg Schmiedmayer from the Vienna University of Technology. They can be shown to occur in very different systems. "Many laws of quantum physics are universal. "You would need a measuring device accelerated to almost the speed of light within a microsecond to see even a tiny Unruh-effect -we can't do that." However, there is another way to learn about this strange effect: using so-called quantum simulators. Sebastian Erne who came from the University of Nottingham to the Atomic Institute of the Vienna University of Technology as an ESQ Fellow a few months ago. "To observe the Unruh effect directly, as William Unruh described it, is completely impossible for us today," explains Dr. ![]() This is due to so-called virtual particles, which are also responsible for other important effects, such as Hawking radiation, which causes black holes to evaporate. The Unruh effect, discovered in 1976 by William Unruh, says that for a strongly accelerated observer the vacuum has a temperature. No-because what looks like a perfect vacuum to one observer can be a turbulent swarm of particles and radiation to the other. But what about the question of whether a certain area of space is empty or not? Shouldn't two observers at least agree on that? How fast does a clock tick? How long is an object? What is the wavelength of a ray of light? There is no universal answer to this, the result is relative-it depends on how fast the observer is moving. ![]() ![]() One of the basic ideas of Albert Einstein's theory of relativity is: Measurement results can depend on the state of motion of the observer. The sound is not created by the detector, rather it is hearing what is there just because of the acceleration (a non-accelerated detector would still hear nothing). This phenomenon is closely related to the Hawking radiation from black holes.Ī research team from the University of Nottingham's Black Hole Laboratory in collaboration with University of British Columbia and Vienna University of Technology has shown that instead of studying the empty space in which particles suddenly become visible when accelerating, you can create a two-dimensional cloud of ultra-cold atoms (Bose-Einstein condensate) in which sound particles, phonons, become audible to an accelerated observer in the silent phonon vacuum. The Unruh effect suggests that if you fly through a quantum vacuum with extreme acceleration, the vacuum no longer looks like a vacuum: rather, it looks like a warm bath full of particles. The team's research has been published today in the journal Physical Review Letters. So far it has not been possible to measure or observe it, but now new research from a team led by the University of Nottingham has shed light on how this could be achieved using sound particles. The Unruh effect combines quantum physics and the theory of relativity. ![]()
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