Testing the computational power of discord

At present, no single feature of the quantum world has been identified as the source of the computational enhancement, efficiency and speed-up of quantum technology. Whilst entanglement is widely recognised as a key resource in quantum technology, an exponential advantage over classical technology can be achieved without it in the presence of non-classical correlations. Furthermore for specific tasks separable states with discord have been proved to be even more efficient than entanglement.
The dynamics of entanglement and discord differ considerably, with entanglement being extremely fragile towards decoherence (even undergoing entanglement "sudden death" ) and discord being much more robust. Since decoherence is a major hurdle to the development of quantum technologies, the investigation of discord is a promising route for progressing the field.
Whilst discord has been proved to be a valuable resource for speed up of specific computational
tasks and for being robust towards decoherence, the more general demonstration that discord can provide
computational enhancement for any computational task has not been provided.This makes discord a very
controversial asset for quantum information processing, although it is widely recognised that if one day it
could be made of use for quantum computation, the impact would be truly ground-breaking.

The goal of this project is to experimentally investigate the physics and the computational power of quantum discord in many-atom
ensembles for a specific algorithm that performs the normalized trace estimation. We will be using the DQC1 model to compute
sums over extremely large strings of numbers, which make the computation classically intractable. As an illustrative example, consider one hundred atoms trapped in an optical dipole trap. A unitary operation on these atoms would be described by a 2^100-by-2^100 matrix. Finding the normalised trace of this matrix is equivalent to adding up 10^30 numbers, which is a task that is classically intractable: modern supercomputers can perform 10^12 operations per second and therefore it would take about the age of the universe to have the same task. This is potentially transformative because quantum discord has not yet been studied in systems with large Hilbert spaces, and the successful demonstration of the exponential speed-up of the computational capability would be a
major leap forward in the field. The ultimate impact of this research idea would be to gain a variety of experimental insights into, and thus a deeper understanding of, the quantum correlations that would be present in all quantum systems

The PI will actively take part in the dissemination of the project results both through specialized seminars at conferences and universities and in peer reviewed publications. The PI will also organize lectures in schools, to promote awareness of quantum information in pre-university pupils.
On a much larger scale, the PI will pursue the broadcasting of dedicated TV programs on quantum information, entanglement and discord. The Open University has a unique agreement with the BBC: over more than 40 years the OU has co-authored a wide variety of very successful scientific programs, and to this day the collaboration with the BBC is central to our role as academics. Whilst the field of quantum information is taking giant steps and a new generation of highly trained and skilled scientists is required in this field, it is remarkable that the media are still devoting a limited amount of broadcasting time to quantum mechanics and quantum information (as compared to, for example, astronomy). The PI will enthusiastically seek an opportunity to work with the BBC on a special issue on quantum computation for the general public, with the aim to increase awareness and widen knowledge in the public sphere. The PI, who has already started making progress in this task, also hopes to engage in this venture other UK/EU colleagues in the field.
The PI has already began the development of an educational video on quantum information and quantum discord for iTunes and the OU youtube channel, as part of an Open University project which exploits our own media development resources.
The OU youtube channel and iTunes services have topped the charts worldwide in terms of downloads and appreciation.
The science faculty at the Open University has employed a full-time business development officer to explore possible routes towards the early commercialization of technologies developed through our various research programs. The PI has independently started making arrangements to raise matching funds for a PhD studentship with the private sector.