Superconducting Quantum Circuit For Light-Matter Interaction And Quantum Simulation

During the last three decades,superconducting circuits as one of the leading candidates for realizing quantum computing and studying quantum optics have attracted much attention.In this platform,one can design circuits containing Josephson junctions that exhibit a wide range of anharmonicity,and thus can be used to mimic atomic energy spectra.Moreover,LC and transmission line resonators encode(approximate)single,and multi-mode light degrees of freedom.The development of this platform promotes research in the field of circuit quantum electrodynamics(cQED).In cQED,the interaction between artificial atom and single microwave photons can reach ultra-strong coupling(USC)regime,and deep-strong coupling regime(DSC),which are not accessible in nature system leading to improved understanding of quantum optics and atomic physics in the microwave domain.Besides,the current scalability and flexibility of this platform provide us a promising toolbox for designing quantum simulators,where by adjusting the external parameter,one can manipulate the internal degree of freedom of the circuit,emulating a wide variety of quantum systems.In this thesis,we follow the aforementioned two applications of this platform i.e.studying the fundamental aspects of light-matter interaction with superconducting circuit and designing a suitable architecture for performing the quantum simulation.The main work is as follows:1.We study the coupling limit of the light-matter interaction with a charge qubit coupled to an LC oscillator on resonance.We show that it is possible to enhance the coupling and achieve the resonant USC/DSC regime,by increasing the impedance of the oscillator.Finally,we extend this result to a two-qubit and oscillator circuit and use this compound USC unit as an incoherent mediator for performing a quantum state transfer protocol.2.On the other hand,we propose a superconducting circuit design for performing the quantum simulation,which consists of a chain of charge qubits coupled through grounded superconducting quantum interference devices(SQUIDs).We show that by controlling the external flux signal through the SQUIDs,we can engineer different inter-qubit interactions obtaining parametrized multi-qubit gates.Finally,we test our architecture by simulating the Fermi-Hubbard model.