Quantum computers and simulators exploit the laws of quantum mechanics to realize a novel computing paradigm. The hope is that superpositions and entanglement of quantum states allow for a much more efficient computation for specific but highly relevant applications.
Most contemporary quantum information processing platforms use two levels, ∣0⟩ and ∣1⟩, called qubits. The aim of NeQST is to elevate this to the next level, by developing the full stack of quantum information processing using d>2 levels, ∣0⟩,∣1⟩,…, ∣d−1⟩: qudits. This approach permits us to compactify quantum information and to tackle problems whose natural description is in terms of d-dimensional degrees of freedom, without encoding overheads.
NeQST tackles all levels of a quantum computer, (i) control of the underlying hardware, (ii) software control packages and simulators, (iii) algorithms for relevant use-cases, (iv) tools to certify the achieved results.
(i) In conventional trapped-ion quantum computers, quantum information is stored in two distinct states of an electron, denoted ∣0⟩ and ∣1⟩-the qubit. However, ions almost always have many more states that could be used to store information. The big opportunity-and challenge-of operating with qudits is the much richer structure to process the quantum information. Within NeQST, we develop new solutions to most efficiently harness the extended qudit spaces.
(ii) Recent accomplishments in the realization of quantum computers and simulators are leading to an exponentially increasing complexity, whose handling demands dedicated methods. The design automation for classical computers was a key to enable their ubiquity we see to today. We believe design automation has the potential to be a similar enabler for quantum computing. We want to push the boundaries on simulation, compilation, and verification as the pillars of design automation and apply them to qudits to fully exploit their potential.
(iii) NeQST will design algorithms for use cases where the additional freedom offered by qudits can become a game changer.
As academic use case, we tackle gauge theories, which describe fundamental particles of nature, such as electrons, positrons, quarks, or gluons. Despite their ubiquity, no efficient classical algorithm exists to compute their dynamical behavior. NeQST will design new algorithms for qudit quantum simulators.
As industrial use case, NeQST focuses on the challenges arising from the growing number of electric vehicles (EVs), which will substantially increase the load on the electricity grid and the variability of electricity production and consumption. Optimizing the distributed operations involved in the (dis-)charging schedules of large numbers of EVs requires novel algorithmic approaches. It is still an open question whether and at which scale quantum computers may offer a speedup in such a context. Yet, it is important to identify and enhance the possibilities quantum computers may offer.
(iv) Present quantum computers are noisy, making it particularly important to certify their quantum performance. In the context of the vastly increased complexity of qudits, this requires the development of new approaches and experimentally feasible tools. We develop techniques to certify that (a) the qudit quantum hardware works as intended, and (b) that it uses intrinsic qudit quantum phenomena.
