Three-qubit entangling gates for spin qubits with simultaneous exchange interactions

Pairwise exchange couplings have long been the standard mechanism for entangling spin qubits in semiconductor systems. However, implementing quantum circuits based on pairwise exchange gates often requires a lengthy sequence of elementary gate operations, including a significant number of SWAP gates for interactions between distant qubits. In this talk, we present an alternative approach: multiqubit entangling gate operations that simultaneously drive the exchange couplings between multiple pairs of spin qubits. We explore three spin qubit systems in linear or triangular configurations. We derive analytical expressions for these multi-exchange entangling operations and demonstrate how to use three-qubit gates to construct quantum circuits capable of generating standard entangled states, such as the GHZ and W states, by optimizing control parameters. Our results show that this multiqubit strategy significantly reduces the number of required operations, offering a pathway to more efficient, shallower, and more coherent circuits for scaling up spin-qubit processors.