Quantum magnetic field receiving device

1 . A quantum magnetic field receiving device comprising:

a superconducting quantum interference device (SQUID) including:

a superconducting loop including a first arm spaced apart from a second arm;

a first Josephson Junction in the first arm;

a second Josephson Junction in the second arm;

a third arm electrically connecting the first arm and the second arm; and

a third Josephson Junction in the third arm, wherein each of the three Josephson Junctions has a junction material; and

an electrostatic gating circuit configured to apply a first electrostatic field to the first Josephson Junction and a second electrostatic field to the second Josephson Junction,

wherein a first critical supercurrent of the junction material of the first Josephson Junction is tuneable by applying the first electrostatic field to the junction material effected by a first gate voltage provided by the electrostatic gating circuit and a second critical supercurrent of the junction material of the second Josephson Junction is tuneable by applying the second electrostatic field to the junction material effected by a second gate voltage provided by the electrostatic gating circuit, and

wherein the first critical supercurrent is tuned to based on the second supercurrent to improve linearity of magnetic flux-to-voltage response of the quantum magnetic field receiving device,

wherein the first and the second critical supercurrent are tuned relative to a third critical supercurrent of the junction material of the third Josephson Junction, and

wherein the third critical supercurrent of the junction material of the third Josephson Junction is tuneable by applying a third electrostatic field to the junction material effected by a third gate voltage provided by the electrostatic gating circuit.

2 . The quantum magnetic field receiving device of claim 1 , wherein the SQUID is a Bi-SQUID.

3 . The quantum magnetic field receiving device of claim 1 wherein the ratio of the first and the second critical supercurrent to the third critical supercurrent is 0.5 to 1.5.

4 . The quantum magnetic field receiving device of claim 1 , wherein an inductance in the first arm is tuned by the electrostatic gating circuit to substantially equal an inductance in the second arm.

5 . The quantum magnetic field receiving device of claim 1 , wherein an inductance in the first arm and an inductance in the second arm is tuned by the electrostatic gating circuit to optimise a Spurious Free Dynamic Range of the quantum magnetic field receiving device.

6 . The quantum magnetic field receiving device of claim 5 , wherein an optimised value of the Spurious Free Dynamic Range resulting from the tuning by the electrostatic gating circuit improves linearity of the magnetic flux-to-voltage response of the quantum magnetic field receiving device above 100 dB.

7 . A quantum magnetic field receiving device comprising:

a superconducting quantum interference filter (SQIF) including:

two or more superconducting loops, each including a first arm spaced apart from a second arm, wherein a second arm of a first superconducting loop forms a first arm of a second superconducting loop;

a first Josephson Junction in the first arm of the first superconducting loop;

a second Josephson Junction in the second arm of the first superconducting loop which forms the first arm of the second superconducting loop; and

a third Josephson Junction in the second arm of second superconducting loop,

wherein each of the first, second and third Josephson Junctions has a junction material; and

an electrostatic gating circuit configured to apply a first electrostatic field to the first Josephson Junction, a second electrostatic field to the second Josephson Junction, and a third electrostatic field to the third Josephson Junction,

wherein a first critical supercurrent of the junction material of the first Josephson Junction is tuneable by applying the first electrostatic field to the junction material effected by a first gate voltage provided by the electrostatic gating circuit and a second critical supercurrent of the junction material of the second Josephson Junction is tuneable by applying the second electrostatic field to the junction material effected by a second gate voltage provided by the electrostatic gating circuit and a third critical supercurrent of the junction material of the third Josephson Junction is tuneable by applying the third electrostatic field to the junction material effected by a third gate voltage provided by the electrostatic gating circuit, and

wherein the first, second and third critical supercurrents are tuned relative to each other to improve linearity of magnetic flux-to-voltage response of the quantum magnetic field receiving device.

8 . The quantum magnetic field receiving device of claim 7 , wherein an inductance in the first arm of the first superconducting loop is tuned by the electrostatic gating circuit based on an inductance in the second arm of the first superconducting loop.

9 . The quantum magnetic field receiving device of claim 7 , wherein an inductance in the first arm and an inductance in the second arm is tuned by the electrostatic gating circuit to optimise a Spurious Free Dynamic Range of the quantum magnetic field receiving device.

10 . The quantum magnetic field receiving device of claim 9 , wherein an optimised value of the Spurious Free Dynamic Range resulting from the tuning by the electrostatic gating circuit improves linearity of the magnetic flux-to-voltage response of the quantum magnetic field receiving device above 100 dB.