Demonstration of a parity-time-symmetry-breaking phase transition using superconducting and trapped-ion qutrits
Alena S. Kazmina, I. V. Zalivako, A. S. Borisenko, Nikita A. Nemkov, Anastasiia S. Nikolaeva, Ilya A. Simakov, Arina V. Kuznetsova, Elena Yu. Egorova, Kristina P. Galstyan, Nikita V. Semenin, A. E. Korolkov, Ilya N. Moskalenko, N. N. Abramov, Ilya S. Besedin, Daria A. Kalacheva, Viktor B. Lubsanov, Aleksey N. Bolgar, Evgeniy O. Kiktenko, K. Yu. Khabarova, Alexey Galda, I. A. Semerikov, N. Kolachevsky, Nataliya Maleeva, Aleksey K. Fedorov
Abstract
Scalable quantum computers hold the promise to solve hard computational problems, such as prime factorization, combinatorial optimization, simulation of many-body physics, and quantum chemistry. While being key to understanding many real-world phenomena, simulation of nonconservative quantum dynamics presents a challenge for unitary quantum computation. In this work, we focus on simulating nonunitary parity-time-symmetric systems, which exhibit a distinctive symmetry-breaking phase transition as well as other unique features that have no counterpart in closed systems. We show that a qutrit, a three-level quantum system, is capable of realizing this nonequilibrium phase transition. By using two physical platforms, an array of trapped ions and a superconducting transmon, and by controlling their three energy levels in a digital manner, we experimentally simulate the parity-time-symmetry-breaking phase transition. Our results indicate the potential advantage of multilevel (qudit) processors in simulating physical effects, where additional accessible levels can play the role of a controlled environment.