TY - JOUR T1 - Observation of measurement-induced quantum phases in a trapped-ion quantum computer Y1 - 2021 A1 - Crystal Noel A1 - Pradeep Niroula A1 - Daiwei Zhu A1 - Andrew Risinger A1 - Laird Egan A1 - Debopriyo Biswas A1 - Marko Cetina A1 - Alexey V. Gorshkov A1 - Michael Gullans A1 - David A. Huse A1 - Christopher Monroe AB -

Many-body open quantum systems balance internal dynamics against decoherence from interactions with an environment. Here, we explore this balance via random quantum circuits implemented on a trapped ion quantum computer, where the system evolution is represented by unitary gates with interspersed projective measurements. As the measurement rate is varied, a purification phase transition is predicted to emerge at a critical point akin to a fault-tolerent threshold. We probe the "pure" phase, where the system is rapidly projected to a deterministic state conditioned on the measurement outcomes, and the "mixed" or "coding" phase, where the initial state becomes partially encoded into a quantum error correcting codespace. We find convincing evidence of the two phases and show numerically that, with modest system scaling, critical properties of the transition clearly emerge.

UR - https://arxiv.org/abs/2106.05881 ER -