A method of operating a photon exchange based quantum network, the network comprising a detection station and a first and second quantum network node, the first and second quantum network node each comprising a laser of the node and a sub-system capable of single photon emission in response to irradiation by a pulse of light from the laser, the detection station comprising a photon arrival detector and a reference laser, the sub-systems of the first and second quantum network nodes being in light communication with the photon arrival detector via respective light transmission paths, the method comprising, in each of the network nodes, - supplying the pulse of light from the laser of the node to the sub-system in the node; - supplying light from the laser of the node into the light transmission path in a time slot preceding a time point at which the network node supplies the pulse of light from the laser of the node; and the method comprising, in the detection station - using a first and/or second optical phase and/or frequency modulator between the photon arrival detector and the respective light transmission paths, to adapt the optical phase and/or frequency transmission between the respective light transmission paths and the photon arrival detector; - measuring a first and second phase difference between light from the reference laser and light transmitted in said time slot of the first and second network nodes respectively; - applying control signals to the first and second optical phase and/or frequency modulator, and adjusting the control signals dependent on the first and second phase difference respectively, so as to establish predetermined phase relations between the reference laser and the light in the detection station due to transmission in said time slot from the first and second network nodes respectively; - maintaining the control signals of the first and second optical phase and/or frequency modulator after said applying and adjusting the control signals, at least until after an expected time of arrival of photons emitted in response to irradiation by a pulse of light in the first and second network nodes. - supplying the pulse of light from the laser of the node to the sub-system in the node; - supplying light from the laser of the node into the light transmission path in a time slot preceding a time point at which the network node supplies the pulse of light from the laser of the node; - using a first and/or second optical phase and/or frequency modulator between the photon arrival detector and the respective light transmission paths, to adapt the optical phase and/or frequency transmission between the respective light transmission paths and the photon arrival detector; - measuring a first and second phase difference between light from the reference laser and light transmitted in said time slot of the first and second network nodes respectively; - applying control signals to the first and second optical phase and/or frequency modulator, and adjusting the control signals dependent on the first and second phase difference respectively, so as to establish predetermined phase relations between the reference laser and the light in the detection station due to transmission in said time slot from the first and second network nodes respectively; - maintaining the control signals of the first and second optical phase and/or frequency modulator after said applying and adjusting the control signals, at least until after an expected time of arrival of photons emitted in response to irradiation by a pulse of light in the first and second network nodes.