Hi, thanks for your reply. I also read the discussion in Questions about parallel execution, where one of the responses mentioned that default.qubit utilizes NumPy broadcasting. It seems that NumPy performs concurrent processing rather than parallel processing.
To further investigate this, I monitored the CPU usage (by using htop on linux) while executing the program, and it showed that only a single CPU core was active. Therefore, I believe that the execution mechanism is concurrent rather than truly parallel.Thanks ! 