But is it really quantum?  This question has been asked up and down the country throughout the UK quantum technology community and also internationally.  It is especially important now that we are starting to move beyond the academic investigation and prototype technologies towards the applied quantum technologies that are the principal aim of our CDT. 

 It is probable the question will be one of the most regularly asked by manufacturers, funders and consumers alike as we seek to introduce quantum technologies into the mainstream.  To answer it, and to do so with authority and clarity, is principally a task for our theoretical colleagues, for to be a genuinely quantum technology requires a proof or at least a demonstration that the same behaviours underlying the application cannot be realised using the familiar classical-physics based resources widely employed at present. 

 This project will seek to provide such theoretical proofs of quantum behaviours for a wide range of prototype candidate quantum technologies and devices including, in particular, those being developed elsewhere within the CDT.  Added to this more formal element will be the aim, and requirement, to explain at the appropriate level what the quantum behaviour is, how we know it is present and also why it is so crucial to the operation of our prototype devices.  Some of the tools we shall use will be derived from established methods within quantum optics and quantum information, such as coherent state probability distributions and Bell-CHSH tests of entanglement, but these will be tailored to practical realities.  Others will require more innovative tests: how, for example, can we demonstrate the quantum behaviour of a very weakly squeezed state of light using only photon-counting statistics accounting for the realities of small detection efficiencies.   

 In the longer term we envisage the information and demonstrations we aim to arrive at will be part of the customers documentation and contract terms for quantum-certified devices.  It may well be that this task will turn out to be one of the most important and certainly the most all-pervading one taken on by our theorists within the CDT.  For this reason, moreover, we can confidently predict that the graduated student will be much in demand.