We propose to build the prototype of a neutron quantum computer (QCN) based on a single ultra-cold neutron bound on a reflecting mirror. The project goal is to construct a multi (logic)-level Q-N-it system, with N ≥ 2, which in addition enables computing with multiple state operations as well. We take advantage of multiple quantum states of the neutrons in the gravity potential of the earth, were all criteria of a QC can be fulfilled. Compared to other quantum computers, the QCN enables multiple-state logic and less complex gate operations.
As neutron sources are limited, a neutron-based quantum computer offers a high potential for security-relevant applications and guarantees exclusive access. The experiments are foreseen at the European Neutron Source at the Institut Laue-Langevin in Grenoble at the beam position PF2. The team endeavors to bind in future commercial partners and possible investors even in an early project phase. NXP Semiconductors, Austria, in Gratkorn and NXP Semiconductors, Germany, in Hamburg have expressed their interest to join later project phases in case of the successful prototype phase. Even the Bundesdruckerei GmbH, Berlin, has expressed their interest in quantum computing based on a multi-logic state approach. At first the consortium consists of groups from TU Wien and ILL. They will build and install a prototype at beam position PF2. Second, University of Heidelberg will work on magnetic field gradients that can be used for CNOT-operations together with a ucn storage technique. TU Wien will also work on compressed states whereas Uni Wien will concentrate on bound entanglement, a question which is related to Hilbert space dimension. QUBITFLOW as a third party contributor will provide higher dimensional quantum logic algorithms.
So far quantum computers require Q-bits to be interconnected e.g. via lasers or other means for performing operations, which becomes challenging as the number of Q-bits increases and limits the scalability of quantum computers. For a QCN the interconnect ability is the same independent of the number of Q-bits. More important, we will extend the architecture to higher dimensional state-computing using Q-N-its, N ≥ 22, exploring higher dimensional quantum algorithms from the experimental and theoretical side. As project aim we will construct a multi Q-2- to Q-5-it systems, where we will perform SWIFT operations as a first step towards quantum fourier transformation.
The higher dimensional gate operations have another decisive advantage. In particular with our Q-16-it system, we will show that the use of compressed states can help to reduce complexity by another factor of 32. The number of states - given by an infinite number of Airy functions with practically no top-cover - has basically a large expansion capability while keeping a highly isolated quantum system. In this respect other aspects of high-dimensional quantum states come into focus. No general method exists to determine to what extend such higher dimensional quantum states are entangled. We will study the process of entanglement distillation, a problem which is strongly connected to a special form of entanglement called bound entanglement (BE) in contrast to weakly or free entangled states.
