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arXiv · 2203.00601

Beyond Ans\"atze: Learning Quantum Circuits as Unitary Operators

Bálint Máté·Bertrand Le Saux·Maxwell Henderson
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Abstract

This paper explores the advantages of optimizing quantum circuits on $N$ wires as operators in the unitary group $U(2^N)$. We run gradient-based optimization in the Lie algebra $\mathfrak u(2^N)$ and use the exponential map to parametrize unitary matrices. We argue that $U(2^N)$ is not only more general than the search space induced by an ansatz, but in ways easier to work with on classical computers. The resulting approach is quick, ansatz-free and provides an upper bound on performance over all ans\"atze on $N$ wires.

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Bálint Máté, Bertrand Le Saux, Maxwell Henderson. 2022-03-01. Beyond Ans\"atze: Learning Quantum Circuits as Unitary Operators. https://arxiv.org/abs/2203.00601

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