Reducing cavity-qubit operation times with antisymmetric pulses for bosonic codes.

Bosonic encoding is a nascent robust path to quantum computation, allowing error correction already at the hardware level.  For an oscillator dispersively coupled to a two level ancilla, the universal control required for computation with any bosonic code was shown to be possible.  However, the rate of control of such systems,  as realized by Transmon coupled to a long-lived mode of a microwave cavity,  is typically limited by the qubit-oscillator dispersive coupling strength [Heeres et al., 2017].

 

In our work, we propose and demonstrate experimentally a symmetry-inspired approach for fast displacement conditioned on the state of the qubit. Our novel method enables fast universal control while avoiding the undesired increase in higher-order terms, such as the Kerr nonlinearity. By focusing on the temporal form of the pulse, our method simplifies the implementation of the fast conditional displacement and greatly reduces the peak power required compared to previous schemes.