This Week at Physics








R. G. Herb Condensed Matter Seminars 

<< Fall 2016  Spring 2017  Summer 2017 >> 
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1. Atomic sized twolevel systems (TLSs) in dielectrics are known as a major source of loss in superconducting devices, particularly due to frequency noise. However, the induced frequency shifts on the devices, even by far offresonance TLSs, is often suppressed by symmetry when standard singletone spectroscopy is used. We introduce a twotone spectroscopy on the normal modes of a pair of coupled superconducting coplanar waveguide resonators to uncover this effect by asymmetric saturation. Together with an appropriate generalized saturation model this enables us to extract the average singlephoton Rabi frequency of dominant TLSs to be Ω0/2π≈79 kHz. At high photon numbers we observe an enhanced sensitivity to nonlinear kinetic inductance when using the twotone method and estimate the value of the Kerr coefficient as K/2π≈−1×10−4 Hz/photon. Furthermore, the lifetime of each resonance can be controlled (increased) by pumping of the other mode as demonstrated both experimentally and theoretically.
2. Multiple bosons undergoing coherent evolution in a coupled network of resonators constitute a socalled quantum walk system. The simplest example of such a twoparticle interference is the celebrated HongOuMandel interference. When scaling to larger boson numbers, simulating the exact distribution of bosons has been shown, under reasonable assumptions, to be exponentially hard. We analyze the feasibility and expected performance of a globally connected superconducting resonator based quantum walk system, using the known characteristics of stateoftheart components. We simulate the sensitivity of such a system to decay processes and to perturbations and compare with coherent input states.