Abstract: According to an example aspect of the present invention, there is provided a method of producing electrodes for superconducting components of quantum computers, quantum sensors or quantum communication devices comprising depositing a first layer on a silicon substrate, the first layer being of a first metal, the first metal being a superconductor, depositing a second layer on the first layer, the second layer being of a second metal, the second metal being a superconductor, and plasma etching through the second layer using a mask layer disposed on the second layer to partially expose the first layer.

Abstract: According to an example aspect of the present invention, there is provided an isolating amplifier apparatus comprising a first 2×2 hybrid coupler and a second 2×2 hybrid coupler, each 2×2 hybrid coupler having a first input port, a second input port, a first output port and a second output port, a first travelling wave parametric amplifier, TWPA, comprising an input connected to the first output port of the first 2×2 hybrid coupler and an output connected to the first input port of the second 2×2 hybrid coupler, and a second travelling wave parametric amplifier, TWPA, comprising an input connected to the second output port of the first 2×2 hybrid coupler and an output connected to the second input of the second 2×2 hybrid coupler.

Abstract: The disclosure relates to a quantum detector configured to receive a microwave signal from a microwave source. The quantum detector comprises a main element formed by a main Josephson junction and a Josephson transmission line which is coupled to the main element for outputting a measurement signal. The Josephson transmission line comprises at least a first set of JTL elements and a second set of JTL elements. The capacitively shunted Josephson junction in each JTL element in the first set is weakly damped, and the JTL element in the second set are more strongly damped than the JTL elements in the first set.

Abstract: A method for providing an electric waveform at a cryogenic temperatures includes providing an optical signal, which comprises an optical waveform, guiding the optical signal into a cryogenic chamber, and converting the optical waveform of the optical signal into an electric waveform inside the cryogenic chamber.

Abstract: The disclosure relates to a quantum detector configured to receive a microwave signal from a microwave source. The quantum detector comprises a main element formed by a main Josephson junction and a Josephson transmission line which is coupled to the main element for outputting a measurement signal. The Josephson transmission line comprises at least a first set of JTL elements and a second set of JTL elements. The capacitively shunted Josephson junction in each JTL element in the first set is weakly damped, and the JTL element in the second set are more strongly damped than the JTL elements in the first set.