Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Product Spectrum Ansatz and the Simplicity of Thermal States   Calculating the physical properties of quantum thermal states is a difficult
problem for classical computers, rendering it intractable for most quantum
many-body systems. A quantum computer, by contrast, would make many of these
calculations feasible in principle, but it is still non-trivial to prepare a
given thermal state or sample from it. It is also not known how to prepare
special simple purifications of thermal states known as thermofield doubles,
which play an important role in quantum many-body physics and quantum gravity.
To address this problem, we propose a variational scheme to prepare approximate
thermal states on a quantum computer by applying a series of two-qubit gates to
a product mixed state. We apply our method to a non-integrable region of the
mixed field Ising chain and the Sachdev-Ye-Kitaev model. We also demonstrate
how our method can be easily extended to large systems governed by local
Hamiltonians and the preparation of thermofield double states. By comparing our
results with exact solutions, we find that our construction enables the
efficient preparation of approximate thermal states on quantum devices. Our
results can be interpreted as implying that the details of the many-body energy
spectrum are not needed to capture simple thermal observables.

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The categories of this paper are: acc-phys
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The categories of this paper are: q-bio
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The categories of this paper are: gr-qc
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The categories of this paper are: math-ph
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The categories of this paper are: physics
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The categories of this paper are: chem-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: funct-an
0
The categories of this paper are: hep-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: solv-int
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The categories of this paper are: stat
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The categories of this paper are: ao-sci
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The categories of this paper are: econ
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The categories of this paper are: nucl-th
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The categories of this paper are: chao-dyn