Method and apparatus of implementing a magnetic shield flux sweeper

1. A shield which protects magnetically sensitive devices, the shield comprising:

a non-superconducting metal or lower transition temperature (T c ) material compared to a higher transition temperature material, disposed in a magnetic field environment;

a temperature control system to cool the non-superconducting metal or lower transition temperature (T c ) material below its transition temperature to create a spatially varying order parameter's |Ψ(r,T)| 2 in said non-superconducting metal or said lower transition temperature material, where Ψ is the superconductivity order parameter, r is a spatial position, and T is temperature;

wherein said spatially varying order parameter is created by a proximity effect, such that said non-superconducting metal or said lower transition temperature material becomes superconductive as a temperature is lowered, creating a flux-free Meissner state, in order to sweep magnetic flux lines to a periphery of said non-superconducting metal or said lower transition temperature material.

2. The shield of claim 1 , wherein said proximity effect is one of a variable thickness proximity effect, a longitudinal proximity effect, an inverse proximity effect, or combination thereof.

3. The shield of claim 2 , the shield further comprising:

a higher transition temperature (T c ) superconducting material disposed on said non-superconducting metal or said lower transition temperature (T c ) material.

4. The shield of claim 3 , wherein said higher transition temperature superconducting material is disposed in a plurality of different patterns on said non-superconducting metal or said lower transition temperature (T c ) material.

5. The shield of claim 4 , wherein the shield is provided in a plurality of heterostructure two-dimensional and three-dimensional structures, including planar and non-planar structures.

6. The shield of claim 5 , wherein the shield comprises a planar disc or a cylinder.

7. The shield of claim 6 , the shield further comprising:

a highest transition temperature (T c ) superconducting material;

wherein said non-superconducting metal or said lower transition temperature material and said higher transition temperature material form a bilayer; and

wherein said highest transition temperature superconducting material is disposed on said bilayer.

8. The shield of claim 7 , wherein said proximity effect is a combination of said longitudinal proximity effect and said variable thickness proximity effect.

9. The shield of claim 6 , wherein the shield is said cylinder; and

wherein said higher transition temperature material is provided in a strip with a width less than a critical length.

10. The shield of claim 6 , wherein said cylinder is open-ended, and said planar disc is provided at one end of said open-ended cylinder.

11. The shield of claim 10 , the shield further comprising:

an intermediate transition temperature superconducting material, said intermediate transition temperature superconducting material having a transition temperature between said higher transition temperature superconducting material and said non-superconducting metal; and

wherein said planar disc comprises said higher transition temperature superconducting material disposed in said plurality of different patterns on one of said intermediate transition temperature superconducting material, or a bilayer of said non-superconducting metal and a superconducting material.

12. The shield of claim 11 , wherein sides of said open-ended cylinder are comprised of said intermediate transition temperature superconducting material, and said non-superconducting metal or said lower transition temperature (T c ) material in a variable thickness; and

wherein said magnetic flux lines are swept outwards from said center of said planar disc to a perimeter of said planar disc, and from a top of said open-ended cylinder where said planar disc is disposed, to a bottom of said open-ended cylinder.

13. The shield of claim 6 , wherein said planar disc comprises said higher transition temperature superconducting material disposed in said plurality of different patterns on a bilayer of said non-superconducting metal and a superconducting material; and

wherein a superconducting lead is connected to one of said non-superconducting metal or said higher transition temperature superconducting material at each of two ends thereof.

14. The shield of claim 13 , the shield further comprising:

a metal bank structure deposited on at least said non-superconducting metal;

wherein said metal bank structure comprises gold.

15. The shield of claim 14 , wherein said non-superconducting metal is gold and said higher transition temperature superconducting material is molybdenum; and

wherein said superconducting lead comprises niobium.

16. The shield of claim 13 , wherein said plurality of different patterns includes another superconducting lead disposed at a center of said planar disc at a greater thickness than at edges thereof, and allows for tuning of the shield; or

wherein said superconducting lead is disposed at edges of said metal bank structure and separately at said center of said planar disc.

17. The shield of claim 4 , wherein trapping regions are disposed at edges of said at least one of said non-superconducting metal or said higher transition temperature superconducting material.

18. The shield of claim 13 , the shield further comprising:

an insulator layer on which said higher transition temperature material is disposed; and

a metal layer ground plane on which said insulator layer is disposed; and

a superconductor disposed at edges of said metal layer ground plane.

19. An array of sensors comprising a plurality of shields of claim 1 .

20. The array of claim 19 , the array further comprising:

a magnetometer disposed in the array;

a continuous superconducting loop around the array; and

a compensating magnetic field coil disposed around the array.

21. A method of protecting a magnetically sensitive device, the method comprising:

creating a spatially varying order parameter's |Ψ(r,T)| 2 in a non-superconducting metal or a lower transition temperature (T c ) material compared to a higher transition temperature material, said non-superconducting metal or said lower transition temperature material being disposed in a magnetic field, where Ψ is the superconductivity order parameter, r is a spatial position, and T is temperature;

wherein said spatially varying order parameter is created by a proximity effect, such that said non-superconducting metal or said lower transition temperature material becomes superconductive as a temperature is lowered, creating a flux-free Meissner state, in order to sweep magnetic flux lines to a periphery of said non-superconducting metal or said lower transition temperature material.

22. An electrical lead of a cryogenic detector, the lead comprising:

a magnetic flux sweeper which uses a proximity effect to create spatially varying order parameter's |Ψ(r,T)| 2 such that upon cooling, the electrical lead becomes superconductive and magnetic flux lines are swept to a periphery creating a flux-free Meissner state in said electrical lead which carries current to and from the cryogenic detector, where Ψ is the superconductivity order parameter, r is a spatial position, and T is temperature.

23. A sensing element of a cryogenic detector comprising:

a magnetic flux sweeper which uses a proximity effect to create spatially varying order parameter's |Ψ(r,T)| 2 such that upon cooling, the sensing element becomes superconductive and magnetic flux lines are swept to a periphery creating a flux-free Meissner state in said sensing element of the cryogenic detector, where Ψ is the superconductivity order parameter, r is a spatial position, and T is temperature.

24. The sensing element of claim 23 , wherein said magnetic flux sweeper is a temperature dependent resistor of a superconducting transition-edge sensor.

25. The sensing element of claim 23 , wherein said magnetic flux sweeper is a temperature dependent magnetic response of a magnetic penetration depth thermometer (MPT).

26. The sensing element of claim 23 wherein said magnetic flux sweeper is a superconducting quantum interference device (SQUID), rf-SQUID, SQUID array, superconducting parametric amplifier, superconducting nanowire detector, superconducting kinetic inductance detector (KID), superconducting mixer, or superconducting q-bit.