Scientists from Russia and Finland used a quantum computer to study an understudied area of physics – non-hermitian quantum mechanics, demonstrating for the first time new possibilities of quantum modeling, allowing to test in practice daring mathematical ideas that contradict the classical rules of physics. The results of the study are published in the journal Communications Physics.
The rules of quantum physics, which determine the behavior of very small objects, use mathematical operators called hermitian Hamiltonians. Hermite operators have been used in quantum physics for almost 100 years, but theorists have recently realized that it is possible to extend its fundamental equations using operators that are not Hermite, that is, operating with a violation of parity and time symmetry, or PT symmetry.
The new equations describe the universe with their own rules: for example, by looking in a mirror and changing the direction of time, you can see the same version of yourself as in the real world. However, existing computational power has so far not allowed creating a model of such a universe.
Researchers from Aalto University in Finland and Artem Melnikov from MIPT have for the first time modeled, using an IBM quantum computer, a toy universe that behaves according to these new rules. To do this, they made the qubits – the elements of the quantum computer that are responsible for calculations – behave according to the new rules of non-hermitian quantum mechanics.
The authors obtained some exciting results. First, it turned out that the application of such operations to qubits led to the loss of quantum information, a phenomenon similar to the hypothetical paradox of disappearing information in a black hole, proposed by Stephen Hawking, which has no explanation within the framework of standard quantum mechanics.
The second exciting result was obtained when the authors experimented with two entangled qubits. Entanglement is the type of correlation that occurs between qubits as if they were experiencing a magical connection that causes each one to synchronize with each other.
Einstein famously disliked the concept of entanglement, calling it “spooky action at a distance.” In conventional quantum physics, it is impossible to change the degree of entanglement between two particles by interfering with only one of them. However, in non-hermitian quantum mechanics, the researchers were able to change the entanglement level of the qubits by manipulating only one of them and obtained a result that is forbidden in ordinary quantum physics.
“The most interesting thing about these results is that quantum computers are now advanced enough to start using them to test unconventional ideas that until now have only been mathematical,” Sorin Paraoanu, associate professor of physics at Aalto University, said in a press release. – In this paper, the “spooky action at a distance” becomes even more frightening. Although we understand very well what is going on, it makes us shudder.”
Although the research is purely theoretical, it has potential practical applications, the authors believe. In particular, several new optical and microwave devices have recently been produced that seem to behave according to the new rules. The present work paves the way for modeling these devices on quantum computers.