  The availability of a universal quantum computer will have fundamental impact
on a vast number of research fields and society as a whole. An increasingly
large scientific and industrial community is working towards the realization of
such a device. An arbitrarily large quantum computer is best constructed using
a modular approach. We present a blueprint for a trapped-ion based scalable
quantum computer module which makes it possible to create a scalable quantum
computer architecture based on long-wavelength radiation quantum gates. The
modules control all operations as stand-alone units, are constructed using
silicon microfabrication techniques and they are within reach of current
technology. To perform the required quantum computations, the modules make use
of long-wavelength-radiation based quantum gate technology. To scale this
microwave quantum computer architecture to an arbitrary size we present a fully
scalable design that makes use of ion transport between different modules,
thereby allowing arbitrarily many modules to be connected to construct a
large-scale device. A high-error-threshold surface error correction code can be
implemented in the proposed architecture to execute fault-tolerant operations.
With only minor adjustments the proposed modules are also suitable for
alternative trapped-ion quantum computer architectures, such as schemes using
photonic interconnects.
