Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Circuit QED with fluxonium qubits: theory of the dispersive regime   In circuit QED, protocols for quantum gates and readout of superconducting
qubits often rely on the dispersive regime, reached when the qubit-photon
detuning {\Delta} is large compared to their mutual coupling strength. For
qubits including the Cooper-pair box and transmon, selection rules dramatically
restrict the contributions to dispersive level shifts {\chi}. By contrast,
without selection rules many virtual transitions contribute to {\chi} and can
produce sizable dispersive shifts even at large detuning. We present theory for
a generic multi-level qudit capacitively coupled to one or multiple harmonic
modes, and give general expressions for the effective Hamiltonian in second and
fourth order perturbation theory. Applying our results to the fluxonium system,
we show that the absence of strong selection rules explains the surprisingly
large dispersive shifts observed in experiments and also leads to the
prediction of a two-photon vacuum Rabi splitting. Quantitative predictions from
our theory are in good agreement with experimental data over a wide range of
magnetic flux and reveal that fourth-order resonances are important for the
phase modulation observed in fluxonium spectroscopy.

17
The categories of this paper are: q-fin
28
The categories of this paper are: alg-geom
3
The categories of this paper are: physics
21
The categories of this paper are: adap-org
8
The categories of this paper are: hep-ex
7
The categories of this paper are: hep-th
35
The categories of this paper are: mtrl-th
10
The categories of this paper are: q-bio
29
The categories of this paper are: funct-an
15
The categories of this paper are: nucl-ex
36
The categories of this paper are: cmp-lg
34
The categories of this paper are: chem-ph
25
The categories of this paper are: patt-sol
9
The categories of this paper are: nlin
20
The categories of this paper are: acc-phys
1
The categories of this paper are: cs