Exploring nanowire structures for quantum information - a route to discoveries and new technological applications

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Classical computers (CC) use classical physics to encode information in binary bits while quantum computers rely on the laws of quantum mechanics (QM) to process information in qubits qubits may simultaneously be in two states due to superposition, and many such qubits can form strongly correlated systems through entanglement, behaving as a single system. Such QM systems are inherently more powerful than CCs, and with sufficiently large numbers of qubits, can solve problems that are intractable with CCs. The search for a perfect platform that simultaneously satisfies requirements of fast quantum control, long coherence times and scalability to thousands of qubits remains a topic of considerable interest. Recently, a new platform based on semiconductor (S) nanowire (NW) heterostructures (HS) has emerged, with qubits showing the fastest electrical spin manipulation times for single spins in QDs. Moreover, the first signatures of Majorana fermions (MFs), which are their own antiparticles and represent the building blocks for topological qubits, have been very recently reported in such NWs. However, these systems are still in their infancy and typically only function in dilution fridge temperatures. NW HS bring: (a) a virtually unlimited choice of materials for both radial and longitudinal HSs as strain may be relieved by unconfined deformation as they grow, and (b) multiple local metal or superconductor (SC) gates may be defined, together with a global back-gate, to provide scalable qubit systems. This proposal examines NW-based schemes addressing shortcomings of current schemes for a scalable QC platform. MF based qubits, through topological protection, should be virtually immune to environment-based decoherence. However, to host them, ballistic (B) NW HS are key - an area where we have demonstrated control over surface state occupation and backscattering to yield state of the art B-NWs; with sufficient quality B-NWs, long thin NWs can be used to enhance immunity. We propose to harness our recent first reports on proximitized SC with high temperature SCs (HTSC), to potentially bring the technology to near-LN2 temperatures something quite new. Next we will explore scalable systems which can be extended into multi-qubit systems. We will also explore the novel possibility of using HTSC/NW-HS systems for gate controlled radiative emission (and two-photon absorption) of entangled photon pairs at elevated temperatures such devices could provide the means to implement “flying” qubits for scalable quantum processing application. We will also explore an alternative platform for dense qubit registers based on self-assembled electron lattices known as the incipient Wigner lattice. This state with entangled e' (spin antiparallel) pairing, can be explored for its' potential for information transmission, computation and memory.