  Astronomical Kinetic Inductance Detectors (KIDs), similar to quantum
information devices, experience performance limiting noise from materials. In
particular, 1/f (frequency) noise can be a dominant noise mechanism, which
arises from Two-Level System defects (TLSs) in the circuit dielectrics and
material interfaces. Here we present a Dual-Resonator KID (DuRKID), which is
designed for improved signal to noise (or noise equivalent power) relative to
1/f-noise limited KIDs. We first show the DuRKID schematic, fabricated circuit,
and we follow with a description of the intended operation, first measurements,
theory, and discussion. The circuit consists of two superconducting resonators
sharing an electrical capacitance bridge of 4 capacitors, each of which hosts
TLSs. The device is intended to operate using hybridization of the modes, which
causes TLSs to either couple to one mode or the other, depending upon which
capacitor they reside in. In contrast, the intended KID signal is directed to
an inductor, and due to hybridization this causes correlated frequency changes
in both (hybridized) modes. Therefore, one can distinguish photon signal from
TLS frequency noise. To achieve hybridization, a TiN inductor is current biased
to allow tuning of one bare resonator mode into degeneracy with the other and
measurements show that the intended resonator modes frequency tune and
hybridize as expected. The interresonator coupling and unintentional coupling
of the 2 resonators to transmission lines are also characterized in
measurements. In the theory, based on a quantum-information-science modes, we
calculate the 4-port S parameters and simulate the 1/f frequency noise of the
device. The study reveals that the DuRKID can exhibit a large and fundamental
performance advantage over 1/f-noise-limited KID detectors.
