SESSION 4: Solid-state implementations

Chair: (Thaddeus Ladd (HRL) )
3:45pm - 4:30pmAlicia Kollar, University of Maryland, College Park (invited)
Band engineering for quantum simulation in circuit QED
Abstract. The field of circuit QED has emerged as a rich platform for both quantum com- putation and quantum simulation. Lattices of coplanar waveguide (CPW) resonators realize artificial photonic materials in the tight-binding limit. Combined with strong qubit-photon interactions, these systems can be used to study dynamical phase tran- sitions, many-body phenomena, and spin models in driven-dissipative systems. I will show that these waveguide cavities are uniquely deformable and can produce lattices and networks which cannot readily be obtained in other systems, including periodic lattices in a hyperbolic space of constant negative curvature. Furthermore, I will show that the one-dimensional nature of CPW resonators leads to degenerate flat bands and that criteria for when they are gapped can be derived from graph-theoretic techniques. The resulting gapped flat-band lattices are difficult to realize in standard atomic crys- tallography, but readily realizable in superconducting circuits.
4:30pm - 5:00pmMattias Fitzpatrick, Princeton University
Charge state instabilities in shallow NV centers for quantum sensing
Abstract. Nitrogen Vacancy (NV) centers in diamond are a promising platform for nanoscale sensing, quantum information processing, and quantum networks. For most sensing applications, due to the decay of target signal outside the diamond, it is advantageous to have NV centers as close as possible to the diamond surface. However, it has been observed that for shallow NV centers, the measurement contrast for Rabi experiments and optically detected magnetic resonance (ODMR) is worse than that for bulk NV centers. Here we demonstrate that the degradation of shallow NV centers Rabi and ODMR contrasts can be associated with dynamics between the two charge states of the NV center (NV$^0$ and NV$^-$). We validate this claim by comparing two distinctly different diamond samples with shallow NVs, one which has charge-state stable NVs and the other with measurably less stable NVs. We measure NV spectra to compare the equilibrium charge state population for NVs in these two samples. Charge state conversion measurements are performed to extract the ionization and recombination rates in the dark and under both green (\unit{532}{\nano\meter}) and orange laser (\unit{590}{\nano\meter}) illumination. Finally, to understand how the charge state population and dynamics are influencing the ESR contrasts, we use time-resolved measurement of NV fluorescence and develop a model of the spin states of NV$^-$ and the NV$^0$ charge state. By fitting the measured fluorescence as function of time to our model, we deduce that the primary cause for lower ESR and Rabi contrast is an increase in the NV$^0$ population and rapid spin-nonconserving charge state conversion at higher laser powers. This research was supported by an appointment to the Intelligence Community Postdoctoral Research Fellowship Program at the Princeton University by Oak Ridge Institute for Science and Education (ORISE) through an interagency agreement between the U.S. Department of Energy and the Office of the Director of National Intelligence (ODNI).

SQuInT Chief Organizer
Akimasa Miyake, Associate Professor

SQuInT Co-Organizer
Brian Smith, Associate Professor UO

SQuInT Program Committee
Postdoctoral Fellows:
Markus Allgaier (UO OMQ)
Sayonee Ray (UNM CQuIC)
Pablo Poggi (UNM CQuIC)
Valerian Thiel (UO OMQ)

SQuInT Event Co-Organizers (Oregon)
Jorjie Arden
Holly Lynn

SQuInT Event Administrator (Oregon)
Brandy Todd

SQuInT Administrator (CQuIC)
Gloria Cordova
505 277-1850

SQuInT Founder
Ivan Deutsch, Regents' Professor, CQuIC Director

Tweet About SQuInT 2020!