Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Revealing the nonlinear response of a tunneling two-level system
  ensemble using coupled modes   Atomic sized two-level systems (TLSs) in amorphous dielectrics are known as a
major source of loss in superconducting devices. In addition, individual TLS
are known to induce large frequency shifts due to strong coupling to the
devices. However, in the presence of a broad ensemble of TLSs these shifts are
symmetrically canceled out and not observed in a typical single-tone
spectroscopy experiment. We introduce a two-tone spectroscopy on the normal
modes of a pair of coupled superconducting coplanar waveguide resonators to
reveal this effect. Together with an appropriate saturation model this enables
us to extract the average single-photon Rabi frequency of dominant TLSs to be
$\Omega_0/2\pi \approx 79 $ kHz. At high photon numbers we observe an enhanced
frequency shift due to nonlinear kinetic inductance when using the two-tone
method and estimate the value of the nonlinear coefficient as $K/2\pi \approx
-1\times 10^{-4}$ Hz/photon. Furthermore, the life-time of each resonance can
be controlled (increased) by pumping of the other mode as demonstrated both
experimentally and theoretically.

18
The categories of this paper are: econ
6
The categories of this paper are: astro-ph
7
The categories of this paper are: hep-th
25
The categories of this paper are: patt-sol
8
The categories of this paper are: hep-ex
10
The categories of this paper are: q-bio
14
The categories of this paper are: math-ph
35
The categories of this paper are: mtrl-th
19
The categories of this paper are: eess
21
The categories of this paper are: adap-org
32
The categories of this paper are: atom-ph
27
The categories of this paper are: comp-gas
1
The categories of this paper are: cs
13
The categories of this paper are: quant-ph
17
The categories of this paper are: q-fin
20
The categories of this paper are: acc-phys