A semiconductor-superconductor hybrid device, comprising: a semiconductor component configured to host a 2-dimensional electron gas or a 2-dimensional hole gas; a superconductor component arranged over the semiconductor component, the superconductor component being capable of inducing superconductivity in a channel region of the semiconductor component by proximity effect; and a set of depletion gates (252, 254, 256) arranged over the semiconductor component, the set of depletion gates (252, 254, 256) being configured to define boundaries of the channel region by depleting charge carriers from regions of the semiconductor component along edges of the channel region; wherein the superconductor component comprises an elongate strip of superconductor material having two ends, at least one of the ends being electrically grounded; wherein the set of depletion gates (252, 254, 256) comprises: at least one first outer depletion gate for defining a first outer segment of the channel region; at least one second outer depletion gate for defining a second outer segment of the channel region; and at least one inner depletion gate for defining an inner segment of the channel region between the first outer segment and the second inner segment; wherein the semiconductor-superconductor hybrid device further comprises: a first junction comprising a first space between the at least one first outer depletion gate and the at least one inner depletion gate, and a first helper gate for gating the first space; a second junction comprising a second space between the at least one second outer depletion gate and the at least one inner depletion gate, and a second helper gate for gating the second space; and wherein the first and second helper gates (270a, 270b) are each operable to connect electrically the channel region to respective leads. a semiconductor component configured to host a 2-dimensional electron gas or a 2-dimensional hole gas; a superconductor component arranged over the semiconductor component, the superconductor component being capable of inducing superconductivity in a channel region of the semiconductor component by proximity effect; and a set of depletion gates (252, 254, 256) arranged over the semiconductor component, the set of depletion gates (252, 254, 256) being configured to define boundaries of the channel region by depleting charge carriers from regions of the semiconductor component along edges of the channel region; wherein the superconductor component comprises an elongate strip of superconductor material having two ends, at least one of the ends being electrically grounded; wherein the set of depletion gates (252, 254, 256) comprises: at least one first outer depletion gate for defining a first outer segment of the channel region; at least one second outer depletion gate for defining a second outer segment of the channel region; and at least one inner depletion gate for defining an inner segment of the channel region between the first outer segment and the second inner segment; at least one first outer depletion gate for defining a first outer segment of the channel region; at least one second outer depletion gate for defining a second outer segment of the channel region; and at least one inner depletion gate for defining an inner segment of the channel region between the first outer segment and the second inner segment; wherein the semiconductor-superconductor hybrid device further comprises: a first junction comprising a first space between the at least one first outer depletion gate and the at least one inner depletion gate, and a first helper gate for gating the first space; a second junction comprising a second space between the at least one second outer depletion gate and the at least one inner depletion gate, and a second helper gate for gating the second space; and a first junction comprising a first space between the at least one first outer depletion gate and the at least one inner depletion gate, and a first helper gate for gating the first space; a second junction comprising a second space between the at least one second outer depletion gate and the at least one inner depletion gate, and a second helper gate for gating the second space; and wherein the first and second helper gates (270a, 270b) are each operable to connect electrically the channel region to respective leads.