Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Optimizing Parameterized Quantum Circuits with Free-Axis Selection   Parameterized quantum circuits (PQCs), which are essential for variational
quantum algorithms, have conventionally been optimized by parameterized
rotational angles of single-qubit gates around predetermined set of axes. We
propose a new method to optimize a PQC by continuous parameterization of both
the angles and the axes of its single-qubit rotations. The method is based on
the observation that when rotational angles are fixed, optimal axes of
rotations can be computed by solving a system of linear equations whose
coefficients can be determined from the PQC with small computational overhead.
The method can be further simplified to select axes freely from continuous
parameters with rotational angles fixed to $\pi$. We show the simplified
free-axis selection method has better expressibility against other structural
optimization methods when measured with Kullback-Leibler (KL) divergence. We
also demonstrate PQCs with free-axis selection are more effective to search the
ground states of Heisenberg models and molecular Hamiltonians. Because
free-axis selection allows designing PQCs without specifying their single-qubit
rotational axes, it may significantly improve the handiness of PQCs.

4
The categories of this paper are: cond-mat
29
The categories of this paper are: funct-an
31
The categories of this paper are: ao-sci
1
The categories of this paper are: cs
12
The categories of this paper are: nucl-th
15
The categories of this paper are: nucl-ex
0
The categories of this paper are: hep-ph
14
The categories of this paper are: math-ph
28
The categories of this paper are: alg-geom
35
The categories of this paper are: mtrl-th
27
The categories of this paper are: comp-gas
30
The categories of this paper are: q-alg
11
The categories of this paper are: hep-lat
36
The categories of this paper are: cmp-lg
9
The categories of this paper are: nlin
7
The categories of this paper are: hep-th