Physics
Permanent URI for this communityhttp://hdl.handle.net/1903/2269
Browse
2 results
Search Results
Item Photon-Mediated Interactions in Lattices of Coplanar Waveguide Resonators(2024) Amouzegar, Maya; Kollár, Alicia; Physics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Circuit quantum electrodynamics (circuit QED) has become one of the main platforms for quantum simulation and computation. One of its notable advantages is its ability to facilitate the study of new regimes of light-matter interactions. This is achieved due to the native strong coupling between superconducting qubits and microwave resonators, and the ability to lithographically define a large variety of resonant microwave structures, for example, photonic crystals. Such geometries allow the implementation of novel forms of photon-mediated qubit-qubit interaction, cross-Kerr qubit-mediated interactions, and studies of many-body physics. In this dissertation, I will show how coplanar waveguide (CPW) lattices can be used to create engineered photon-mediated interactions between superconducting qubits. I will discuss the design and fabrication of a quasi one-dimensional lattice of CPW resonators with unconventional bands, such as gapped and ungapped flat bands. I will then present experimental data characterizing photon-mediated interactions between tunable transmon qubits and qubit-mediated non-linear photon-photon interactions in the said lattice. Our results indicate the realization of unconventional photon-photon interactions and qubit-qubit interactions, therefore, demonstrating the utility of this platform for probing novel interactions between qubits and photons. In future design iterations, one can extend the study of these interactions to two-dimensional flat and hyperbolic lattices.Item Excited Nucleon and Delta Spectra From Lattice QCD(2009) Engelson, Eric; Wallace, Stephen J; Physics; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)We calculate the nucleon and delta excited state spectra from lattice QCD. Operators which transform as irreducible representations of the lattice symmetry group are used as bases for variational calculations. We compute matrices of corre- lation functions between all the operators in the variational bases. From the time dependence of the eigenvalues of these matrices, we extract energy eigenvalues. By subducing the continuum SU(3) rotation group to the octahedral group, we can identify the spins of the continuum states which correspond to the lattice states. In the nucleon spectrum calculation, we use 24^3 × 64 anisotropic lattices with pion masses of 416 MeV and 576 MeV. The lattices have a spacing of about 0.1 fm and an anisotropy of 3. We use the Wilson gauge and the Wilson fermion actions with two flavors of dynamical light quarks. The low-lying spectrum has many of the qualitative features of the physical spectrum and we are able to identify the continuum states which correspond to several of the lattice states. This includes one of the first observations of a spin- 5 state on the lattice. For the delta spectrum calculation, we use 16^3 × 128 anisotropic lattices. The gauge action is the tree-level tadpole improved Wilson gauge action, while in the fermion sector we use the clover action. The pion mass is about 390 MeV and the anisotropy is 3.5. We have two flavors of dynamical light quarks as well as dynamical strange quarks. To compute the correlation functions, we use the distillation method in which operators are projected on the the low lying eigenmodes of the Laplacian operator, allowing for an exact computation of all-to-all propagators between the distilled source and sink operators. We are able to identify four low-lying states with continuum delta states.