Multiqubit entangling gates with multi-exchange interactions between spin qubits*

In the pursuit of optimizing quantum circuits, the prevailing quantum computing paradigm leverages a sequence of quantum gates, primarily composed of one- and two-qubit gate operations from a universal set. While these gates are versatile, their utilization often necessitates lengthy sequences, posing challenges for quantum coherence and circuit complexity. Notably, for semiconductor quantum dot systems employing spin qubits, the exchange interaction between neighboring spin qubits has emerged as the standard mechanism for enabling two-qubit gates. However, the short-range nature of this exchange coupling imposes a significant overhead when implementing such gates between distant qubits.

In this study, we explore an alternative approach to optimize quantum circuits, where the exchange interaction is harnessed simultaneously across multiple qubits. This technique not only simplifies the practical implementation but also holds promise for enhancing quantum circuit efficiency. Through numerical optimization methods, we seek to identify optimal quantum circuits using this multi-qubit exchange interaction approach.

Our research investigates the efficacy of this method in generating typical entangled states and compares it with the conventional exchange-based approach. We demonstrate that the multi-qubit exchange interaction approach considerably reduces the depth of quantum circuits, showcasing its potential for efficiently implementing large-scale quantum computations. This work underscores the practicality and efficiency of employing multi-qubit exchange interactions as a valuable tool for quantum circuit optimization.