Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Practical and Efficient Hamiltonian Learning   With the fast development of quantum technology, the size of quantum systems
we can digitally manipulate and analogly probe increase drastically. In order
to have a better control and understanding of the quantum hardware, an
important task is to characterize the interaction, i.e., to learn the
Hamiltonian, which determines both static or dynamic properties of the system.
Conventional Hamiltonian learning methods either require costly process
tomography or adopt impractical assumptions, such as prior information of the
Hamiltonian structure and the ground or thermal states of the system. In this
work, we present a practical and efficient Hamiltonian learning method that
circumvents these limitations. The proposed method can efficiently learn any
Hamiltonian that is sparse on the Pauli basis using only short time dynamics
and local operations without any information of the Hamiltonian or preparing
any eigenstates or thermal states. The method has scalable complexity and
vanishing failure probability regarding the qubit number. Meanwhile, it is free
from state preparation and measurement error and robust against a certain
amount of circuit and shot noise. We numerically test the scaling and the
estimation accuracy of the method for transverse field Ising Hamiltonian with
random interaction strengths and molecular Hamiltonians, both with varying
sizes. All these results verify the practicality and efficacy of the method,
paving the way for a systematic understanding of large quantum systems.

31
The categories of this paper are: ao-sci
24
The categories of this paper are: dg-ga
12
The categories of this paper are: nucl-th
27
The categories of this paper are: comp-gas
1
The categories of this paper are: cs
20
The categories of this paper are: acc-phys
32
The categories of this paper are: atom-ph
33
The categories of this paper are: plasm-ph
22
The categories of this paper are: chao-dyn
15
The categories of this paper are: nucl-ex
26
The categories of this paper are: bayes-an
14
The categories of this paper are: math-ph
37
The categories of this paper are: supr-con
25
The categories of this paper are: patt-sol
3
The categories of this paper are: physics
5
The categories of this paper are: gr-qc