Quantum-based realizations of the pascal: status and progress of the EMPIR-project: quantumpascal

The QuantumPascal (QP) project combines the capabilities of 12 European institutions to enable traceable pressure measurements utilizing quantum-based methods that evaluate the number density instead of force per area to target the wide pressure range between 1 Pa and 3 MPa. This article summarizes the goals and results since the project start in June 201

Two-way coherent frequency transfer in a commercial DWDM communication network in Sweden

An experimental fiber link is being established between SP Technical Research Institute of Sweden in Boras and Chalmers University of Gothenburg in Sweden. The one way fiber length is about 60 km and implemented in SUNET (Swedish University Network). The aim of the project is to evaluate the signal quality when sending a stable optical frequency utilizing a wavelength in a DWDM (Dense Wavelength Division Multiplexing) system fiber pair. The experiment uses a channel in the DWDM with the wavelength of 1542.14 nm. This wavelength is within the C band and is therefore compatible with common Erbium doped amplifiers in this network. Another aim of the system is to be ultra-stable which corresponds to a stability of 1 710-13 for τ = 1 s as well as providing the ability to distribute monitored ultra-stable frequency with a future traceability to UTC (SP) (National realization of Universal Time Coordinated within Sweden) to multiple users within the network. Measurements of an optical frequency transfer using a fiber-link based on unidirectional light signals in parallel fibers have shown promising results in a free-running setup and in a lab environment. The fractional frequency stability, analyzed as the Overlapping Allan deviation, is approximately 3 710-13 at τ = 10 s and almost 1 710-14 at 105 s

Coherent optical two-way frequency transfer in a commercial DWDM network

An experimental fiber connection for ultra-stable optical frequency transfer is established between SP Technical Research Institute of Sweden in Bor\ue5s and Chalmers University of Technology in Gothenburg. The distance is approximately 60 km, and the connection is implemented in the Swedish University Computer Network. The sites are connected through an active flexible communication network where each optical channel can be configured with terminal equipment based on the user needs. The network is implemented with unidirectional optical amplifiers and duplex fibers. The signal quality and the stability when sending an optical coherent frequency utilizing a wavelength in a DWDM system fiber pair, is evaluated within this work. The aim of the system is to be ultra-stable which corresponds to a stability of 10-13 for t = 1 s (Overlapping Allan Variance), as well as providing the ability to distribute monitored ultra-stable frequency with a future traceability to UTC (SP) to multiple users within the future network. This paper describes the current status and results from the frequency transfer between SP and Chalmers

Coherent optical two-way frequency transfer in a commercial DWDM network

An experimental fiber connection for ultra-stable optical frequency transfer is established between SP Technical Research Institute of Sweden in Bor\ue5s and Chalmers University of Technology in Gothenburg. The distance is approximately 60 km, and the connection is implemented in the Swedish University Computer Network. The sites are connected through an active flexible communication network where each optical channel can be configured with terminal equipment based on the user needs. The network is implemented with unidirectional optical amplifiers and duplex fibers. The signal quality and the stability when sending an optical coherent frequency utilizing a wavelength in a DWDM system fiber pair, is evaluated within this work. The aim of the system is to be ultra-stable which corresponds to a stability of 10-13 for t = 1 s (Overlapping Allan Variance), as well as providing the ability to distribute monitored ultra-stable frequency with a future traceability to UTC (SP) to multiple users within the future network. This paper describes the current status and results from the frequency transfer between SP and Chalmers