Excellence
 
This is an excellent proposal with a very high probability of success
in all the proposed tasks (maybe too high). Risk assessment has been
considered and concrete solutions have been devised in the work
packages design.The competence of the team is unquestionable since it
contains the creators of the ZX and AZX calculus. The goals for each
task are clear and there is the possibility of a very strong impact in
research and in industry. There is an appropriate interplay between
theoretical development and experimental research.However, it should
be stressed that the non-incremental aspect of this proposal is not
entirely ensured. The fact is that this proposal basically aims at
implementing the already existing AZX concept in (more or less)
practical systems. This gives some degree of predictability to the
proposal but at the same time does not demonstrate a fundamental
breakthrough which would constitute a major advantage with respect to
other proposals in this call.A considerable strength of the proposal
comes from the long history of cross collaboration of the team which
guarantees the effective complementarity of all the component sub
teams. 

Highly useful and relevant proposal which will accelerate the
development of applications on quantum computing hardware. Similar to
the development of concepts like UNIX, this will be transformational,
providing the glue between software development and bespoke
hardware. Although a step removed from actual QC implementation, this
work is essential and also provides a foundation for the future
Flagship. The recent developments including theoretical proofs show
the fruitfulness of this area and enhance the proposal. Inclusion of
the ability to perform quantum error correction is also an essential
element. The project appears very well timed, with ZX-calculus making
great strides theoretically.

The goal of this proposal is to develop an intermediate language for
quantum computers that will serve as a translator between a
higher-level language and the hardware.  This builds on previous work
on the ZX calculus by members of the consortium.  The hardware end
will focus on two architectures, superconducting and ion trap.  With
the advent of few-qubit quantum computers this project is a timely
one.The project is well structured.  The tasks are arranged so that
the easiest ones can be tackled first.  The results of these initial
tasks can them be integrated into the longer-term, more difficult
ones.    Besides the theoretical work, there is an industrial
collaboration and there will be collaborations with experimental
efforts, one using superconducting technology and the other using
optically-linked ion traps.  All of this indicates that the project
should have a high probability of success.While the project is novel
and not incremental, it falls mostly within the field of computer
science.  There will be some interaction with experimental groups, and
this will bring in a bit of physics.  However, what this project is
trying to accomplish is important, and the fact that it is primarily a
computer science project should not be regarded as a problem. 
 
Impact
 
This proposal aims at creating an “abstraction layer” for quantum
computation that makes the computation process independent of the
underlying hardware. This is a mandatory step if quantum computation
is to become the standard in the near future. This is, therefore, a
very strong point in favour of the proposal.To have a series of
workshops and schools to disseminate the results is quite interesting
and valuable to build a continual development of the subject in the
following years. Taken abstractly this should also be considered a
strong point in favour of the proposal.On the other hand, it is not
entirely clear from what is described in the proposal what the
dissemination tasks will bring to future programmers. Will they use
the outcome of this project as a black box of which they know nothing
about, thus enforcing the creation of a new professional layer in the
IT world? If this is bound to become in the future an industry
standard it might be worthwhile to discuss this issue thoroughly
because it will have a strong and long lasting impact in the IT labour
structure. As such, this is a weak point in the proposal that is not
addressed properly.

IF it can be made to work then the impact is massive and means that
software will automatically take advantage of improvements and
developments in hardware as well as making simple portability across
platforms possible and smooth. Apart from anything else, this allows a
ready comparison capability between hardware platforms – running
similar speed tests, each optimised / prepared using the same
intermediate language. Ultimately this approach could result in a
language that is embedded at a low level with the hardware – similar
to X86 machine code. A concern is that this approach is counter to
convention (the gate approach) and this will inevitably slow down the
impact, but the benefits outweigh the risks in terms of producing a
radically new way to interface software and quantum hardware. Another
concern is simply the risk that the project doesn’t deliver, given the
radical nature of the ideas proposed. But the gains again seem to
outweigh this risk. 

The results of this project could be truly significant.  Currently,
the way in which a quantum computer is programed depends on the
hardware.  This hardware-dependence needs to be eliminated, in order
to make quantum programming platform independent and make quantum
computers more useful. Results will be disseminated through the
relevant journals and workshops.  Software tools will be released on
an open-source basis. 
 
Quality and efficiency of the implementation
 
Strengths:-The work plan is well designed and feasible with well
designed tasks and risk mitigation measures correctly considered.- The
management structure is appropriate.- The expertise for the different
work packages is guaranteed- Correct allocation of tasks.Weaknesses:-
It is not clear how the results of this proposal can percolate
correctly to industry if this is to become a standard in quantum
computing.

The attention to testing and monitoring / measurement of classical
information makes the project more practical but even better is the
link to two very different hardware implementations as a means to
practically verify the universal approach sought here. The project is
still addressing the concept at an early stage and so much work will
remain once the project is complete. Direct links with NQIT are highly
beneficial to the project, given the world leading status of ion trap
based qubits at Oxford.Making the resulting software open to the
community is also highly positive.

The work plan is well planned, and the management structure is
reasonable.  This is an ambitious project, and, consequently, there is
a risk of failure.  Steps have been taken to identify risks and deal
with problems should they arise.  The research timeline has been
arranged to tackle some of the easier tasks first while simultaneously
working on longer-term and more difficult goals, guaranteeing that
there will be results and leaving time to address the more ambitious
goals.  The consortium consists of members from both academia and
industry, and people working in the more theoretical aspects of
computer science along with others working on specific implementations
of quantum computing.  In this case, the whole is greater than the sum
of the parts.  The expertise in the consortium is appropriate to the
project.
 
General comments
 
This feels like a high risk project, proposing to overturn the
gate-based approach to quantum software programming in favour of a
radical new method relying on XZ calculus. However, the returns on the
investment would be highly significant, allowing the porting of
software across multiple hardware platforms. It is unclear that there
would be much in the way of side-benefits, should the main challenge
fall short.