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An initialization strategy for addressing barren plateaus in parametrized quantum circuits

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Edward Grant1, Leonard Wossnig1, Mateusz Ostaszewski2, and Marcello Benedetti3

1Rahko Limited & Department of Computer Science, University College London
2Institute of Theoretical and Applied Informatics, Polish Academy of Sciences
3Cambridge Quantum Computing Limited & Department of Computer Science, University College London

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Abstract

Parametrized quantum circuits initialized with random initial parameter values are characterized by barren plateaus where the gradient becomes exponentially small in the number of qubits. In this technical note we theoretically motivate and empirically validate an initialization strategy which can resolve the barren plateau problem for practical applications. The technique involves randomly selecting some of the initial parameter values, then choosing the remaining values so that the circuit is a sequence of shallow blocks that each evaluates to the identity. This initialization limits the effective depth of the circuits used to calculate the first parameter update so that they cannot be stuck in a barren plateau at the start of training. In turn, this makes some of the most compact ansätze usable in practice, which was not possible before even for rather basic problems. We show empirically that variational quantum eigensolvers and quantum neural networks initialized using this strategy can be trained using a gradient based method.

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► References

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Cited by

[1] Jacques Carolan, Masoud Mohseni, Jonathan P. Olson, Mihika Prabhu, Changchen Chen, Darius Bunandar, Murphy Yuezhen Niu, Nicholas C. Harris, Franco N. C. Wong, Michael Hochberg, Seth Lloyd, and Dirk Englund, “Variational quantum unsampling on a quantum photonic processor”, arXiv:1904.10463, Nature Physics (2020).

[2] Ryan LaRose, Arkin Tikku, Étude O’Neel-Judy, Lukasz Cincio, and Patrick J. Coles, “Variational Quantum State Diagonalization”, arXiv:1810.10506.

[3] Brian Coyle, Daniel Mills, Vincent Danos, and Elham Kashefi, “The Born Supremacy: Quantum Advantage and Training of an Ising Born Machine”, arXiv:1904.02214.

[4] Mateusz Ostaszewski, Edward Grant, and Marcello Benedetti, “Quantum circuit structure learning”, arXiv:1905.09692.

[5] Marcello Benedetti, Erika Lloyd, Stefan Sack, and Mattia Fiorentini, “Parameterized quantum circuits as machine learning models”, Quantum Science and Technology 4 4, 043001 (2019).

[6] Guillaume Verdon, Michael Broughton, Jarrod R. McClean, Kevin J. Sung, Ryan Babbush, Zhang Jiang, Hartmut Neven, and Masoud Mohseni, “Learning to learn with quantum neural networks via classical neural networks”, arXiv:1907.05415.

[7] Sukin Sim, Peter D. Johnson, and Alan Aspuru-Guzik, “Expressibility and entangling capability of parameterized quantum circuits for hybrid quantum-classical algorithms”, arXiv:1905.10876.

[8] Cristina Cirstoiu, Zoe Holmes, Joseph Iosue, Lukasz Cincio, Patrick J. Coles, and Andrew Sornborger, “Variational Fast Forwarding for Quantum Simulation Beyond the Coherence Time”, arXiv:1910.04292.

[9] Max Wilson, Sam Stromswold, Filip Wudarski, Stuart Hadfield, Norm M. Tubman, and Eleanor Rieffel, “Optimizing quantum heuristics with meta-learning”, arXiv:1908.03185.

[10] Arthur G. Rattew, Shaohan Hu, Marco Pistoia, Richard Chen, and Steve Wood, “A Domain-agnostic, Noise-resistant, Hardware-efficient Evolutionary Variational Quantum Eigensolver”, arXiv:1910.09694.

[11] Francesco Tacchino, Panagiotis Barkoutsos, Chiara Macchiavello, Ivano Tavernelli, Dario Gerace, and Daniele Bajoni, “Quantum implementation of an artificial feed-forward neural network”, arXiv:1912.12486.

[12] Jules Tilly, Glenn Jones, Hongxiang Chen, Leonard Wossnig, and Edward Grant, “Computation of molecular excited states on IBMQ using a Discriminative Variational Quantum Eigensolver”, arXiv:2001.04941.

The above citations are from Crossref’s cited-by service (last updated successfully 2020-01-22 09:35:12) and SAO/NASA ADS (last updated successfully 2020-01-22 09:35:14). The list may be incomplete as not all publishers provide suitable and complete citation data.

Source: https://quantum-journal.org/papers/q-2019-12-09-214/

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