**(SciTech)** Aalto researchers have used an IBM quantum computer to explore an overlooked area of physics, and have challenged 100-year-old cherished notions about information at the quantum level.

The rules of quantum physics — which govern how very small things behave — use mathematical operators called Hermitian Hamiltonians. Hermitian operators have underpinned quantum physics for nearly 100 years but recently, theorists have realized that it is possible to extend its fundamental equations to making use of Hermitian operators that are not Hermitian. The new equations describe a universe with its own peculiar set of rules: for example, by looking in the mirror and reversing the direction of time you should see the same version of you as in the actual world. In their new paper, a team of researchers led by Docent Sorin Paraoanu used a quantum computer to create a toy-universe that behaves according to these new rules. The team includes Dr. Shruti Dogra from Aalto University, first author of the paper, and Artem Melnikov, from MIPT and Terra Quantum.

The researchers made qubits, the part of the quantum computer that carries out calculations, behave according to the new rules of non-Hermitian quantum mechanics. They demonstrated experimentally a couple of exciting results which are forbidden by regular Hermitian quantum mechanics.

The research also has potential applications. Several novel optical or microwave-based devices developed in recent times do seem to behave according to the new rules. The present work opens the way to simulating these devices on quantum computers.