Look-ahead Schemes for Nearest Neighbor Optimization of 1D and 2D Quantum Circuits

Robert Wille, Oliver Keszöcze, Marcel Walter, Patrick Röhrs, Anupam Chattopadhyay, Rolf Drechsler

In: 21st Asia and South Pacific Design Automation Conference. Asia and South Pacific Design Automation Conference (ASP-DAC-21) 21st January 25-28 Macau China 2016.


Ensuring nearest neighbor compliance of quantumcircuits by inserting SWAP gates has heavily been consideredin the past. Here, quantum gates are considered which workon non-adjacent qubits. SWAP gates are applied in order to“move” these qubits onto adjacent positions. However, a decisionhow exactly the SWAPs are “moved” has mainly been madewithout considering the effect a “movement” of qubits mayhave on the remaining circuit. In this work, we propose amethodology for nearest neighbor optimization which addressesthis problem by means of a look-ahead scheme. To this end,two representative implementations are presented and discussedin detail. Experimental evaluations show that, in the best case,reductions in the number of SWAP gates of 56% (compared to thestate-of-the-art methods) can be achieved following the proposedmethodology.

Deutsches Forschungszentrum für Künstliche Intelligenz
German Research Center for Artificial Intelligence