Nuclear spin-wave quantum register for a solid-state qubit.

Solid-state nuclear spins surrounding individual, optically addressable qubits1,2 are a crucial resource for quantum networks3-6, computation7-11 and simulation12. Although hosts with sparse nuclear spin baths are typically chosen to mitigate qubit decoherence13, developing coherent quantum systems in nuclear-spin-rich hosts enables exploration of a much broader range of materials for quantum information applications. The collective modes of these dense nuclear spin ensembles provide a natural basis for quantum storage14; however, using them as a resource for single-spin qubits has thus far remained elusive. Here, by using a highly coherent, optically addressed 171Yb3+ qubit doped into a nuclear-spin-rich yttrium orthovanadate crystal15, we develop a robust quantum control protocol to manipulate the multi-level nuclear spin states of neighbouring 51V5+ lattice ions. Via a dynamically engineered spin-exchange interaction, we polarize this nuclear spin ensemble, generate collective spin excitations, and subsequently use them to implement a quantum memory. We additionally demonstrate preparation and measurement of maximally entangled 171Yb-51V Bell states. Unlike conventional, disordered nuclear-spin-based quantum memories16-24, our platform is deterministic and reproducible, ensuring identical quantum registers for all 171Yb3+ qubits. Our approach provides a framework for utilizing the complex structure of dense nuclear spin baths, paving the way towards building large-scale quantum networks using single rare-earth ion qubits15,25-28.

Efficacy of different doses of intranasal dexmedetomidine in preventing emergence agitation in children with inhalational anaesthesia: A prospective randomised trial.

BACKGROUND: Emergence agitation is a common paediatric complication after inhalational anaesthesia. Intranasal dexmedetomidine can prevent emergence agitation effectively, but the optimal dose is uncertain. OBJECTIVE: The aim of our study was to investigate the 95% effective dose (ED 95 ) of intranasal dexmedetomidine for the prevention of emergence agitation after inhalational anaesthesia for paediatric ambulatory surgery. DESIGN: A prospective, randomised, placebo-controlled, double-blind, clinical trial. SETTING: The study was conducted in Guangzhou Women and Children's Medical Center in China from August 2017 to December 2018. PATIENTS: Three hundred and eighteen children scheduled for ambulatory surgery were enrolled into two age groups of less than 3 years and at least 3 years. INTERVENTIONS: The children in each age group were randomised into five equal subgroups to receive either intranasal dexmedetomidine 0.5, 1.0, 1.5 or 2.0 µg kg -1 (Groups D 0.5 , D 1.0 , D 1.5 and D 2.0 ), or intranasal isotonic saline (group C) after induction. MAIN OUTCOME MEASURES: The primary outcome was the ED 95 dose of intranasal dexmedetomidine for preventing emergence agitation after inhalational anaesthesia for paediatric ambulatory surgery. RESULTS: The incidences of emergence agitation for Groups C, D 0.5 , D 1.0 , D 1.5 and D 2.0 were 63, 40, 23, 13 and 3% in children less than 3 years, and 43, 27, 17, 7 and 3% in children at least 3 years. The ED 95 of intranasal dexmedetomidine for preventing emergence agitation was 1.99 µg kg -1 [95% confidence interval (CI), 1.83 to 3.80 µg kg -1 ] in children less than 3 years, and 1.78  µg kg -1 (95% CI, 0.93 to 4.29 µg kg -1 ) in children at least 3 years. LMA removal time for groups D 1.5 and D 2.0 was 9.6 ±â€Š2.2 and 9.7 ±â€Š2.5 min, respectively, for children less than 3 years, and 9.4 ±â€Š2.0 and 9.9 ±â€Š2.7 min in children at least 3 years, respectively. Length of stay in the postanaesthesia care unit for Groups D 1.5 and D 2.0 was 34.3 ±â€Š9.6 and 37.1 ±â€Š11.2 min, respectively, in children less than 3 years, and 34.7 ±â€Š10.2 and 37.3 ±â€Š8.3 min in children at least 3 years, respectively. These times were longer in the D 1.5 and D 2.0 subgroups than in the control subgroup in the two age groups of less than 3 years and at least 3 years, respectively: 7.2 ±â€Š1.9 min in children less than 3 years and 7.3 ±â€Š2.5 min in children at least 3 years for LMA removal time, 22.2 ±â€Š7.9 min in children less than 3 years and 22.0 ±â€Š7.7 min in children at least 3 years for PACU stay time in control subgroup, respectively ( P  < 0.05). CONCLUSION: Intranasal dexmedetomidine prevented emergence agitation after paediatric surgery in a dose-dependent manner. The optimal dose of intranasal dexmedetomidine for preventing emergence agitation was higher in younger children. TRIAL REGISTRY: chictr.org.cn: ChiCTR-IOR-17012415.

Development of a Blood Pressure Measurement Instrument with Active Cuff Pressure Control Schemes.

This paper presents an oscillometric blood pressure (BP) measurement approach based on the active control schemes of cuff pressure. Compared with conventional electronic BP instruments, the novelty of the proposed BP measurement approach is to utilize a variable volume chamber which actively and stably alters the cuff pressure during inflating or deflating cycles. The variable volume chamber is operated with a closed-loop pressure control scheme, and it is activated by controlling the piston position of a single-acting cylinder driven by a screw motor. Therefore, the variable volume chamber could significantly eliminate the air turbulence disturbance during the air injection stage when compared to an air pump mechanism. Furthermore, the proposed active BP measurement approach is capable of measuring BP characteristics, including systolic blood pressure (SBP) and diastolic blood pressure (DBP), during the inflating cycle. Two modes of air injection measurement (AIM) and accurate dual-way measurement (ADM) were proposed. According to the healthy subject experiment results, AIM reduced 34.21% and ADM reduced 15.78% of the measurement time when compared to a commercial BP monitor. Furthermore, the ADM performed much consistently (i.e., less standard deviation) in the measurements when compared to a commercial BP monitor.