Losses in physical channels, such as optical fibres, limit existing quantum communication systems to modest distance ranges. Since amplification of quantum signals is fundamentally not possible, we look to extend the range and functionality of these quantum channels by adding quantum memory nodes that can daisy-chain multiple lengths of quantum channels through entanglement and thus extend the communication distance — an approach known as ‘quantum repeater’. Quantum repeaters are by necessity hybrid devices, as they connect flying qubits (photons) to small processors for error correction and privacy amplification. In this project we develop a two-node proof-of-principle hybrid quantum repeater system. We generate entangled photon pairs from quantum dots embedded in semiconductor nanowire and store them in atomic quantum memories following a frequency up-conversion. We expect this will enable quantum key distribution over long distances at rates exceeding those possible through a direct link. The photon-pair sources, the frequency converters, as well as the quantum memories will be implemented in compact on-chip platforms. This novel approach combines the advantages available from a deterministic and tunable solid-state source of bright entangled photon pairs with the potential for high-efficiency long-lived quantum memory that is achievable with laser cooled atoms. The ultimate goal is to achieve a working pair of quantum repeater nodes at practically relevant wavelengths that would lead to useful rates for long-distance quantum key distribution.
Materials for Majorana-based Topological Qubits
Summary Topological qubits offer a novel pathway to scalable quantum computing by simultaneously allowing for ease of coupling between qubits and strong decoupling of qubits from noise and dissipation. The most promising direction explores the topologically induced protection of theoretically predicted exotic quasiparticles, the so-called Majorana Zero Modes or MZMs. To-date MZMs, which follow […]
January 28, 2019
Implementing High-fidelity Quantum Gates in Multi-level Trapped Ions
Summary The scalability of quantum processors is limited by current error rates for single-qubit gates. By encoding more than a single bit of information within a single ion, multi-level “qudits” offer a promising method of increasing the information density within a quantum processor, and therefore minimizing the number of gates and associated error rates. […]
July 30, 2018
Molecular Scale Magnetic Resonance Imaging
Through its phenomenal ability to image soft tissues, magnetic resonance imaging (MRI) has revolutionized both clinical medicine and research biomedicine.
September 9, 2016