  Variational quantum algorithms (VQAs) are among the most promising algorithms
to achieve quantum advantages in the NISQ era. One important challenge in
implementing such algorithms is to construct an effective parameterized quantum
circuit (also called an ansatz). In this work, we propose a single entanglement
connection architecture (SECA) for a bipartite hardware efficient ansatz (HEA)
by balancing its expressibility, entangling capability, and trainability.
Numerical simulations with a one-dimensional Heisenberg model and quadratic
unconstrained binary optimization (QUBO) issues were conducted. Our results
indicate the superiority of SECA over the common full entanglement connection
architecture (FECA) in terms of computational performance. Furthermore,
combining SECA with gate-cutting technology to construct distributed quantum
computation (DQC) can efficiently expand the size of NISQ devices under low
overhead. We also demonstrated the effectiveness and scalability of the DQC
scheme. Our study is a useful indication for understanding the characteristics
associated with an effective training circuit.
