Leveraging dynamic circuits

Abstract

Dynamic circuits — mid-circuit measurements and real-time classical communications that allow us to change the circuit on the fly - will be essential to a myriad of quantum computing protocols. Not in the least will they be a critical component of future quantum error correction schemes. In this talk, I will discuss a new proposal and implementation of a circuit to prepare an error suppressed magic state with high yield on a superconducting qubit device using dynamic circuits. Magic states are used to complete a universal set of logic gates, but conventionally they are costly to prepare using distillation. It is therefore valuable to find ways of reducing the resource cost of producing high fidelity magic states. We can reduce this resource cost by preparing better encoded magic states. Remarkably, we find that our error-suppressed encoding circuit demonstrates a magic state preparation fidelity of (1.87 ± 0.16)× $10^{-2}$, exceeding that of an unencoded preparation on the same device. We show beyond break-even fidelity on encoded magic state even using real-time feedforward. Furthermore, we show that adaptive circuit elements that are conditioned in real time on mid-circuit measurement outcomes increase the yield compared to implementation with post selection.