Tunable-profile qubit-photon bound state interactions with superconducting circuits

Strongly coupling qubits to the band edge of a photonic crystal results in the formation of qubit-photon dressed bound states. The photonic components of these bound states are exponentially localized around the qubit positions and represent the inter-bound state interaction profiles. Tunability of the exponential localization length of bound state interactions has been experimentally demonstrated in superconducting circuits of two transmons coupled to a microwave photonic crystal [1]. To expand the range of 1D quantum models that can be probed with qubits coupled to photonic crystals, proposals have been put forth to engineer non-exponential interaction profiles by further dressing the systems with external driving fields [2]. We present experimental progress towards characterizing the effective bound states of transmons coupled to photonic crystals driven by auxiliary microwave tones. By driving the photonic crystal with multiple tones we aim to engineer non-exponential effective interactions, with the goal of accessing a broader class of tunable spin models.

[1] Sundaresan et al. arXiv:1801.10167
[2] Douglas et al. Nat Pho 9, 326–331, 2015