Quantum simulation with periodically driven superconducting circuits

V. M. Bastidas, Chen Zha, Ming Gong +18 more

Andrew Houck

Yijie Yao, Jiarui Zeng, Yao Yao

Abstract Avoided crossings are always assumed to be a natural result of degeneracy lift. In order to perform quantum simulations of this, one can utilize a Rydberg atom periodically driven by a microwave field, and by further coupling to a superconducting (SC) quantum circuit, the avoided crossing can be largely enhanced depending on the coupling strength. The entire diagram of transition probability is investigated and the parameter regimes for the facilitation of avoided crossings are determined, which will be extremely useful for realistic experimental designs. We then employ the Floquet theory to calculate the quasi-energy distribution of the Rydberg atom, especially in the blue-detuning regime. The opening and closing of the quasi-energy gap is surprisingly found to be insensitive to the frequency of the SC circuit. The anharmonicity of the circuit is also analyzed.

Huikai Xu, Jing-Ning Zhang, Jiaxiu Han +5 more

Floquet engineering, i.e. driving the system with periodic Hamiltonians, not only provides great flexibility in analog quantum simulation, but also supports phase structures of great richness. It has been proposed that Floquet systems can support a discrete time-translation symmetry (TTS) broken phase, dubbed the discrete time crystal (DTC). This proposal, as well as the exotic phase, has attracted tremendous interest among the community of quantum simulation. Here we report the observation of the DTC in an one-dimensional superconducting qubit chain. We experimentally realize long-time stroboscopic quantum dynamics of a periodically driven spin system consisting of 8 transmon qubits, and obtain a lifetime of the DTC order limited by the coherence time of the underlying physical platform. We also explore the crossover between the discrete TTS broken and unbroken phases via various physical signatures. Our work extends the usage of superconducting circuit systems in quantum simulation of many-body physics, and provides an experimental tool for investigating non-equilibrium dynamics and phase structures.

Yasunobu Nakamura

U. Las Heras, Laura García-Álvarez, Lucas Lamata +1 more