Multimode superconducting microwave cavities provide a hardware efficient means of engineering a large Hilbert space with high coherence, suitable for quantum simulations and information processing. Coupling to a superconducting transmon circuit results in random access control [1], with logic gates possible between arbitrary pairs of cavity modes. I will present our progress towards realizing such a processor using the quantum flute - a seamless rectangular 3D multimode cavity, with a tailored mode dispersion and lifetimes approaching a millisecond for ~10 modes. We present various schemes for controlling the cavity states using interactions mediated by the dispersively coupled transmon. 4-wave mixing processes induced by the non-linearity of the transmon can be used to exchange quantum states between the transmon and the cavity modes in a few hundred nanoseconds. When driven off-resonantly, these sideband drives can be used to controllably dress the cavity states, and engineer novel multimode interactions. These interactions can also be used to compensate multimode-state-dependent Stark shifts, and perform generalized parity measurements, crucial for high fidelity gate operations and quantum error correction.
[1] Naik, R. K., et al. "Random access quantum information processors using multimode circuit quantum electrodynamics." Nature Communications 8, 1904 (2017).
Dr. Srivatsan Chakram, University of Chicago
Host: Jens Koch
Keywords: Physics, Astronomy, Condensed Matter