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.
Fabrication of Ultra Low Noise RF SQUID Amplifiers
A superconducting quantum interference device (SQUID) is an extremely sensitive magnetic field detector.
June 1, 2017
Quantum State Tomography with Machine Learning
Summary An important challenge in building a quantum computer is quantifying the level of control obtained in the preparation of a quantum state. The state of a quantum device is characterized from experimental measurements, using a procedure known as tomography. Exact tomography requires a vast amount of computer resources, making it prohibitive for quantum […]
June 6, 2018
Qubits and Quantum Effects in Biology
It is unknown whether biological processes make direct use of quantum effects, as opposed to depending merely on the influence of quantum physics on chemical bonding and molecular structure.
June 1, 2017
Quantum Material Multilayer Photonic Devices and Network
Summary Realizing highly integrated quantum photonic devices on a chip can enable new opportunities for photonic quantum computation. In this project, we explore heterostructures of stacked two-dimensional (2D) materials, such transition metal dichalcogenides (TMDC) or graphene, combined with optical microcavities as a platform for such devices. 2D materials are extremely thin and flexible, and have […]
December 12, 2019