Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Measuring out-of-time-ordered correlation functions with a single
  impurity qubit in a bosonic Josephson junction   We calculate the out-of-time-ordered correlation function (OTOC) of a single
impurity qubit coupled to fully a connected many-particle system such as a
bosonic Josephson junction or spins with long-range interactions. In these
systems the qubit OTOC can be used to detect both ground state and excited
state quantum phase transitions (QPTs), making it a robust order parameter that
is considerably more sensitive than the standard one-body correlation function.
Finite size scaling exponents for an $N$ body system can also be accurately
extracted from the long-time OTOC dynamics, however, for short times there is a
discrepancy due to the fact that the qubit has not had enough time to couple to
the larger system. Our results show that the OTOC of even the smallest probe is
enough to diagnose a QPT in fully connected models but, like a continuous
measurement, can still cause a backaction effect which leads to weakly chaotic
dynamics and gradual information scrambling.

1
The categories of this paper are: cs
35
The categories of this paper are: mtrl-th
24
The categories of this paper are: dg-ga
32
The categories of this paper are: atom-ph
10
The categories of this paper are: q-bio
0
The categories of this paper are: hep-ph
22
The categories of this paper are: chao-dyn
14
The categories of this paper are: math-ph
18
The categories of this paper are: econ
30
The categories of this paper are: q-alg
37
The categories of this paper are: supr-con
9
The categories of this paper are: nlin
23
The categories of this paper are: solv-int
16
The categories of this paper are: stat
26
The categories of this paper are: bayes-an
8
The categories of this paper are: hep-ex