Universität zu Köln

Anselmetti, Gian-Luca R., Wierichs, David, Gogolin, Christian and Parrish, Robert M. (2021). Local, expressive, quantum-number-preserving VQE ansatze for fermionic systems. New J. Phys., 23 (11). BRISTOL: IOP Publishing Ltd. ISSN 1367-2630

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Abstract

We propose VQE circuit fabrics with advantageous properties for the simulation of strongly correlated ground and excited states of molecules and materials under the Jordan-Wigner mapping that can be implemented linearly locally and preserve all relevant quantum numbers: the number of spin up (alpha) and down (beta) electrons and the total spin squared. We demonstrate that our entangler circuits are expressive already at low depth and parameter count, appear to become universal, and may be trainable without having to cross regions of vanishing gradient, when the number of parameters becomes sufficiently large and when these parameters are suitably initialized. One particularly appealing construction achieves this with just orbital rotations and pair exchange gates. We derive optimal four-term parameter shift rules for and provide explicit decompositions of our quantum number preserving gates and perform numerical demonstrations on highly correlated molecules on up to 20 qubits.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Anselmetti, Gian-Luca R. UNSPECIFIED UNSPECIFIED UNSPECIFIED Wierichs, David UNSPECIFIED UNSPECIFIED UNSPECIFIED Gogolin, Christian UNSPECIFIED UNSPECIFIED UNSPECIFIED Parrish, Robert M. UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-570575
DOI:	10.1088/1367-2630/ac2cb3
Journal or Publication Title:	New J. Phys.
Volume:	23
Number:	11
Date:	2021
Publisher:	IOP Publishing Ltd
Place of Publication:	BRISTOL
ISSN:	1367-2630
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language Physics, Multidisciplinary Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/57057