Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Many-body quantum lock-in amplifier   Achieving high-precision detection of time-dependent signals in noisy
environment is a ubiquitous issue in physics and a critical task in metrology.
Lock-in amplifiers are detectors that can extract alternating signals with a
known carrier frequency from an extremely noisy environment. Here, we present a
protocol for achieving an entanglement-enhanced lock-in amplifier via empoying
many-body quantum interferometry and periodic multiple pulses. Generally,
quantum interferometry includes three stages: initialization, interrogation,
and readout. The many-body quantum lock-in amplifier can be achieved via adding
suitable periodic multiple-$\pi$-pulse sequence during the interrogation. Our
analytical results show that, by selecting suitable input states and readout
operations, the frequency and amplitude of an unknown alternating field can be
simultaneously extracted via population measurements. In particular, if we
input spin cat states and apply interaction-based readout operations, the
measurement precisions for frequency and amplitude can both approach the
Heisenberg limit. Moreover, our many-body quantum amplifier is robust against
extreme stochastic noises. Our study may point out a new direction for
measuring time-dependent signals with many-body quantum systems, and provides a
feasible way for achieving Heisenberg-limited detection of alternating signals.

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The categories of this paper are: dg-ga
10
The categories of this paper are: q-bio
33
The categories of this paper are: plasm-ph
5
The categories of this paper are: gr-qc
15
The categories of this paper are: nucl-ex
16
The categories of this paper are: stat
37
The categories of this paper are: supr-con
17
The categories of this paper are: q-fin
12
The categories of this paper are: nucl-th
32
The categories of this paper are: atom-ph
35
The categories of this paper are: mtrl-th
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The categories of this paper are: patt-sol
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The categories of this paper are: acc-phys
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The categories of this paper are: bayes-an
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The categories of this paper are: ao-sci
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The categories of this paper are: funct-an