The giant atom regime of quantum acoustics

Ao-Lin Guo, Le-Tian Zhu, Guang‐Can Guo +3 more

The giant atom regime where the wavelength of the phonon field is smaller than the atomic size opens up new opportunities for exploring exotic phenomena and developing powerful quantum technologies. Here, we explore the radiation dynamics of a hybrid system consisting of a superconducting giant atomic ensemble and an acoustic waveguide. In particular, we show how to design the delayed feedback of the slow acoustic field on the giant atomic ensemble. This modulates the phonon superradiant dynamics into engineerable revival modes and unconventional scaling laws with respect to the number of giant atoms. These are a distinctive feature of time-delayed collective processes that have no analog in other settings. The recipes we provide for harnessing collective giant atoms can be exported to other platforms, laying the foundation for a variety of quantum simulations and applications.

Hassan Gholibeigian

Thomas Aref, Per Delsing, Maria K. Ekström +6 more

Xinyu Li, Wei Zhao, Zhihai Wang

We investigate the single photon scattering in a phonon-photon hybrid system in the waveguide quantum electrodynamics (QED) scheme. In our consideration, an artificial giant atom, which is dressed by the phonons in a surface acoustic wave resonator, interacts with a coupled resonator waveguide (CRW) nonlocally via two connecting sites. Together with the interference effect by the nonlocal coupling, the phonon serves as a controller to the transport of the photon in the waveguide. On the one hand, the coupling strength between the giant atom and the surface acoustic wave resonator modulates the width of the transmission valley or window in the near resonant regime. On the other hand, the two reflective peaks induced by the Rabi splitting degrade into a single one when the giant atom is large detuned from the surface acoustic resonator, which implies an effective dispersive coupling. Our study paves the way for the potential application of giant atoms in the hybrid system.

Thomas Brennan

David D. Noachtar, Johannes Knörzer, Robert H. Jonsson

Superconducting circuits coupled to acoustic waveguides have extended the range of phenomena that can be experimentally studied using tools from quantum optics. In particular, giant artificial atoms permit the investigation of systems in which the electric dipole approximation breaks down and pronounced non-Markovian effects become important. While previous studies of giant atoms focused on the realm of the rotating-wave approximation, we go beyond this and perform a numerically exact analysis of giant atoms strongly coupled to their environment, in regimes where counter-rotating terms cannot be neglected. To achieve this, we use a Lanczos transformation to cast the field Hamiltonian into the form of a one-dimensional chain and employ matrix-product state simulations. This approach yields access to a wide range of system-bath observables and to relatively unexplored parameter regimes.