Quantenparadoxien durch neue Röntgentechniken entschlüsselt

> An international team of physicists has devised a method to test alternatives to standard quantum theory, proposing a possible explanation for why quantum effects don’t appear in larger objects like cats.

> According to standard quantum theory, before an object is observed it can exist in a superposition state with multiple contradictory properties.

> In experiments, such superpositions have been observed in objects as large as a sapphire crystal weighing in at 16 micrograms, for example. According to standard quantum theory, superpositions could, in principle, persist in even bigger objects. But we do not see these superpositions in everyday life.

> “For some reason, these wavefunctions when observed are prone to ‘collapse’–at which point, quantum systems behave like everyday ‘classical’ systems, losing their genuine quantum attributes,” says Curceanu. “But standard quantum theory cannot tell us how or why this happens. This is the essence of the so-called ‘measurement problem’ in quantum mechanics.”

> The measurement problem led independent teams of scientists to develop a suite of different explanations, among which are ‘quantum collapse models’–rival alternatives to standard quantum theory “that propose a physical process triggers the collapse of the wavefunction in such a way that the bigger the system is, the faster the collapse goes,” says Curceanu. These models are exciting because they predict effects that are not present in standard quantum mechanics, in the form of spontaneous radiation, Curceanu explains.

> There are two main types of quantum collapse models: The first are called Continuous Spontaneous Localization (CSL) models, in which the collapse is caused by an intrinsic, random process, which may or may not be related to gravity or something else. This process happens spontaneously and continuously. In the second set of models, the collapse is related explicitly to gravity–for instance, in the so-called Diósi-Penrose models. But, as yet, they have found no evidence for spontaneous radiation.

> In their most recent work they calculated the features of the spontaneous electromagnetic radiation that should be emitted from atomic systems at lower energies, in the X-ray domain. The team found big differences with previous expectations for the simplest models. “Quite surprisingly, in this low-energy regime the spontaneous radiation rate was found to strongly depend on the atomic species under investigation,” says Piscicchia. “**For the first time, the emission was also found to depend on the specific collapse model**,” adds Manti.

> Curceanu and her colleagues are updating their own experiment performed at the LNGS-INFN underground laboratory in Italy, to search for these X-rays. They plan to explore the predicted relationship between the spontaneous radiation and the atomic structure in dedicated experiments using several targets. “This would allow us to better constrain the collapse models and, if a signal is found, to pin down what causes it, which, of course, **would have enormous implications in all science,”** Curceanu says.