Entanglement of nanophotonic quantum memory nodes in a telecom network.

A key challenge in realizing practical quantum networks for long-distance quantum communication involves robust entanglement between quantum memory nodes connected by fibre optical infrastructure1-3. Here we demonstrate a two-node quantum network composed of multi-qubit registers based on silicon-vacancy (SiV) centres in nanophotonic diamond cavities integrated with a telecommunication fibre network. Remote entanglement is generated by the cavity-enhanced interactions between the electron spin qubits of the SiVs and optical photons. Serial, heralded spin-photon entangling gate operations with time-bin qubits are used for robust entanglement of separated nodes. Long-lived nuclear spin qubits are used to provide second-long entanglement storage and integrated error detection. By integrating efficient bidirectional quantum frequency conversion of photonic communication qubits to telecommunication frequencies (1,350 nm), we demonstrate the entanglement of two nuclear spin memories through 40 km spools of low-loss fibre and a 35-km long fibre loop deployed in the Boston area urban environment, representing an enabling step towards practical quantum repeaters and large-scale quantum networks.

Reported level of pain of upper extremities related to multi-factorial workloads among office workers during and after work hours.

OBJECTIVES: This research compared the level of reported pain between women workers with high workload (main work involved typing) and women workers with low workload (various office work where typing was not the main task). The research examined the relationship between reported pain of upper extremities (UE) and the following variables: physical strain exerted during typing on a computer keyboard, extra-work strain on UE, bio-demographic variables, psychosocial variables, and ergonomic variables. STUDY DESIGN: Participants were 60 women who worked in offices, divided into two groups. The index group included women whose main work involved typing (high workload: M=6.16 h of typing per day), and the control group did various office work where typing was not the main task (low workload: M=3.23 h of typing per day). The level of pain, physical strain, and data concerning bio-demographic variables, psychosocial variables and ergonomic variables was assessed by a self-reported questionnaire. RESULTS: The results suggested that there was a significant difference between workers with high and low typing workloads. Workers with higher typing load reported higher levels of pain. There was a significant positive correlation between level of reports of pain and levels of physical overload at work, and extra-work strain on UE both among workers with high and low workloads. It was also found that levels of pain correlated significantly with bio-demographic variables (age and number of children) and psychosocial variables (managerial responsibilities) among low workload workers only. CONCLUSIONS: The research on pain of UE indicates that pain may be affected by a multi-factorial nature of a work-related environment which includes physical strain exerted during typing on a computer keyboard, extra-work strain on UE, bio-demographic variables and psychosocial variables.