qi.py 文件源码

def __trace_middle_dims(sys, dims, reverse=True):
    """
    Get system dimensions for __trace_middle.

    Args:
        j (int): system to trace over.
        dims(list[int]): dimensions of all subsystems.
        reverse (bool): if true system-0 is right-most system tensor product.

    Returns:
        Tuple (dim1, dims2, dims3)
    """
    dpre = dims[:sys]
    dpost = dims[sys + 1:]
    if reverse:
        dpre, dpost = (dpost, dpre)
    dim1 = int(np.prod(dpre))
    dim2 = int(dims[sys])
    dim3 = int(np.prod(dpost))
    return (dim1, dim2, dim3)