Patent Publication Number: US-2021175010-A1

Title: Superconducting shield for cryogenic chamber

Description:
FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     This invention was made with United States Government support. The United States Government has certain rights in the invention. 
    
    
     TECHNICAL FIELD 
     Various embodiments relate to shield for a cryogenic chamber. For example, various embodiments relate to a shield configured to provide a highly uniform magnetic field region within a cryogenic chamber. 
     BACKGROUND 
     In various scenarios, an action (e.g., experiment, controlled state evolution, reaction, function performance, and/or the like) is to be carried out an action temperature that is a cryogenic temperature. Generally, temperatures in the range of 0 K to 124 K are considered cryogenic temperatures. Some of these actions require precise control of other environmental parameters in addition to temperature. For example, the action may require being performed within a region where the magnetic field is substantially free of fluctuations. However, the Earth&#39;s magnetic field and/or magnetic fields generated by electrical components in the vicinity of where the action is taking place may cause the local magnetic field to have significant fluctuations. 
     BRIEF SUMMARY OF EXAMPLE EMBODIMENTS 
     Example embodiments provide methods for shielding a cryogenic chamber, a cryogenic chamber comprising a superconducting shield, a superconducting shield for use with a cryogenic chamber, and/or the like. In various embodiments, the cryogenic chamber may comprise an action chamber within which one or more actions may be performed corresponding action temperatures. For example, the actions may include performing an experiment, a controlled state evolution, a chemical reaction, performing a function, and/or the like. In various embodiments, the action temperatures are cryogenic temperatures (e.g., within the range of 0 K to 124 K). 
     According to a first aspect, a shield for a cryogenic chamber is provided. In an example embodiment, the shield comprises an interior shield at least partially sandwiched within housing walls of the cryogenic chamber. The housing walls define an action chamber within the cryogenic chamber. The action chamber is configured to be cryogenically cooled to an action temperature. The interior shield is made of a first material that acts as a superconductor at the action temperature. 
     According to another aspect, a cryogenic chamber comprising a shield is provided. In an example embodiment, the cryogenic chamber comprises an interior housing comprising housing walls that define an action chamber. The action chamber is configured to be cryogenically cooled to an action temperature. The cryogenic chamber further comprises an interior shield at least partially sandwiched within the housing walls. The interior shield is made of a first material that acts as a superconductor at the action temperature. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S) 
       Having thus described the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein: 
         FIG. 1  provides a schematic diagram of an example action system, in accordance with an example embodiment. 
         FIG. 2  provides a cross-section view of an example cryogenic chamber, in accordance with an example embodiment. 
         FIG. 3  provides a cross-section view of another example cryogenic chamber, in accordance with an example embodiment. 
         FIG. 4  provides a perspective view of an example cryogenic chamber, in accordance with an example embodiment. 
         FIG. 5  provides a perspective view of shield for a cryogenic chamber, in accordance with an example embodiment. 
         FIG. 6  provides a top view of the shield shown in  FIG. 5 . 
         FIG. 7  provides a partial cross-section view of the shield shown in  FIG. 5 . 
         FIG. 8  provides a schematic diagram of an example action chamber within an interior housing, in accordance with an example embodiment. 
         FIG. 9  provides a schematic diagram of an example computing entity that may be used in accordance with an example embodiment. 
     
    
    
     DETAILED DESCRIPTION OF SOME EXAMPLE EMBODIMENTS 
     The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all embodiments of the invention are shown. Indeed, the invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. The term “or” (also denoted “/”) is used herein in both the alternative and conjunctive sense, unless otherwise indicated. The terms “illustrative” and “exemplary” are used to be examples with no indication of quality level. The terms “generally” and “approximately” refer to within engineering and/or manufacturing limits and/or within user measurement capabilities, unless otherwise indicated. Like numbers refer to like elements throughout. 
     As described above, in various cryogenic systems, it is important to be able to precisely control the magnetic field within an action chamber of the cryogenic system. For example, to accurately carry out an action within the action chamber of the cryogenic system, the magnetic field in the action chamber may be controlled to have very few and/or very small fluctuations. In various embodiments, the cryogenic chamber of the cryogenic system comprises a shield configured to dampen, reduce, diminish, and/or minimize fluctuations in the magnetic field within the action chamber. In various embodiments, the shield comprises an interior shield that is at least partially embedded within an interior housing of the cryogenic chamber that defines the action chamber. In various embodiments, the interior shield is made of a first material that acts as a superconductor (e.g., has approximately zero resistivity) at an action temperature. The cryogenic system is configured to maintain the action chamber at the action temperature. 
     In various embodiments, the action chamber is defined by an interior housing of the cryogenic chamber. For example, the interior housing may be disposed within the cryogenic chamber. The interior housing may comprise housing walls that define the action chamber within the interior housing. In various embodiments, the shield comprises an interior shield that is at least partially sandwiched within the housing walls of the interior housing. For example, at least some of the housing walls of the interior housing may comprise an exterior wall portion and an interior wall portion. At least a portion of the interior shield may be sandwiched between the exterior wall portion and the interior wall portion, in an example embodiment. In various embodiments, the interior shield comprises at least one sheet or film of a first material. In various embodiments, the first material is a metal, metal alloy, and/or the like. In various embodiments, the first material is a superconductor at the action temperature. For example, in an example embodiment where the action temperature is a cryogenic temperature (e.g., less than approximately 124 K). 
     In various embodiments, the cryogenic chamber comprises an outer housing that defines a main chamber of the cryogenic chamber. For example, the interior housing and the action chamber are disposed within the main chamber of the cryogenic chamber. In various embodiments, an exterior shield is disposed outside of the outer housing. For example, the exterior shield may comprise at least one sheet of a second material that dads the outer surface of the outer housing. In various embodiments, the second material is a metal, metal alloy, and/or other low resistivity material. In various embodiments, the second material may be different from the first material of the interior shield. In various embodiments, the exterior shield is expected to be at an outer shield temperature when the action chamber is maintained at the action temperature (e.g., by a cryogenic system). In various embodiments, the second material has low resistivity and/or is a superconductor at the outer shield temperature. In an example embodiment, the outer shield temperature is in the range of approximately 30-100K. In an example embodiment, the outer temperature is approximately 40 K. 
     In various embodiments, one or more intermediate shields may be disposed between an inner surface of the outer housing and the housing walls of the interior housing. In an example embodiment, two intermediate shields are disposed between the inner surface of the outer housing and the housing walls of the interior housing. For example, an intermediate shield may be disposed within the main chamber and outside of the interior housing. In various embodiments, an intermediate shield comprises at least one sheet of a third material. The third material may be a metal, metal alloy, and/or other low resistivity material. In various embodiments, the third material may be different from the first material of the interior shield and/or the second material of the outer shield. In various embodiments, the intermediate shield is expected to be at an intermediate temperature when the action chamber is maintained at the action temperature (e.g., by a cryogenic system). In various embodiments, the third material has low resistivity and/or is a super conductor at the intermediate temperature. In an example embodiment, the intermediate temperature is in the range of approximately 30-100K. In an example embodiment, the intermediate temperature is 40 K. 
     In various embodiments, the interior housing and outer housing include one or more access openings. In various embodiments, the access openings may provide an optical path for a laser beam to enter the action chamber for use in the action, provide an optical path for photons generated during the action to leave the action chamber, permit a fiber optic or electrical cable to pass through the outer and/or interior housing, and/or the like. In various embodiments, the interior, outer, and/or intermediate shields comprise shield openings corresponding to access openings. For example, the interior shield comprises a shield opening corresponding to each access opening of the interior housing. For example, the exterior shield comprises a shield opening corresponding to each access opening of the outer housing. In various embodiments, the intermediate shield may comprise a shield opening corresponding to each access opening of the interior and/or outer housing. In an example embodiment, the interior shield, intermediate shield, and/or exterior shield comprises a tube stub extending outward from the shield opening. For example, a tube stub may be hollow cylinder having substantially the same or smaller diameter as the shield opening. The tube stub may be secured to the corresponding shield at the perimeter of the shield opening and extend outward from the shield. In various embodiments, a tube stub is made of the same material as the corresponding shield and is in electrical contact with the corresponding shield. 
     In various embodiments, the shield comprises an interior shield at least partially sandwiched within the housing walls of the interior housing of a cryogenic chamber. In various embodiments, the shield further comprises an exterior shield and/or an intermediate shield. In various embodiments, the interior shield comprises one or more tube stubs about a shield opening therein. In various embodiments, the exterior shield and/or the intermediate shield comprises one or more tube stubs about a shield opening therein. In various embodiments, the shield is configured to provide a very homogenous magnetic field region within the action chamber. For example, the shield may be configured to reduce, diminish, and/or minimize magnetic field fluctuations within the action chamber. In various embodiments, the action chamber is configured to be maintained at an action temperature which is a cryogenic temperature (e.g., via a cryogenic system). In various embodiments, the interior shield is made of a first material that is a super conductor at the action temperature. 
     In an example embodiment, the cryogenic system is part of a quantum computer, such as a trapped ion quantum computer. In an example embodiment, the actions include preparing one or more qubits of the quantum computer (e.g., within an ion trap), performing a controlled state evolution of one or more qubits of the quantum computer (e.g., via application of one or more gates), stimulating emission of one or more qubits of the quantum computer (e.g., to read the qubit), and/or the like. 
     Exemplary Quantum Computer System 
       FIG. 1  provides a schematic diagram of an example trapped ion quantum computer system  100 , in accordance with an example embodiment. In various embodiments, the trapped ion quantum computer system  100  comprises a computing entity  10  and a quantum computer  110 . In various embodiments, the quantum computer  110  comprises a controller  30 , a cryogenic chamber  40  enclosing an ion trap  50 , and one or more laser sources  60 . In various embodiments, the one or more laser sources  60  are configured to provide one or more laser beams to the ion trap  50  within an action chamber  432  (See  FIG. 3 ) of the cryogenic chamber  40 . In an example embodiment, the cryogenic chamber and/or a portion thereof (e.g., including the action chamber) is also a vacuum chamber. 
     In various embodiments, a computing entity  10  is configured to allow a user to provide input to the quantum computer  110  (e.g., via a user interface of the computing entity  10 ) and receive, view, and/or the like output from the quantum computer  110 . The computing entity  10  may be in communication with the controller  30  via one or more wired or wireless networks  120  and/or via direct wired and/or wireless communications. In an example embodiment, the computing entity  10  may translate, configure, format, and/or the like information/data, quantum computing algorithms, and/or the like into a computing language, executable instructions, command sets, and/or the like that the controller  30  can understand and/or implement. 
     In various embodiments, the controller  30  is configured to control the ion trap  50 , cryogenic system  45  and/or vacuum system controlling the temperature and pressure within the cryogenic chamber  40 , and/or other systems controlling the environmental conditions (e.g., temperature, humidity, pressure, and/or the like) within the cryogenic chamber  40 . For example, the cryogenic system  45  may be configured to maintain the action chamber  432  at the action temperature. In various embodiments, the action temperature is a cryogenic temperature (e.g., in the range of approximately 124 K to 0 K) and the cryogenic system  45  is a cryogenic cooling system. In various embodiments, the cryogenic system  45  is also comprises a vacuum system configured to maintain the main chamber  442  and/or the action chamber  432  at a particular pressure. In various embodiments, the controller  30  is configured to control various components of the quantum computer  110  in accordance with executable instructions, command sets, and/or the like provided by the computing entity  10 . In various embodiments, the controller  30  is configured to receive output from the quantum computer  110  (e.g., from an optical collection system) and provide the output and/or the result of a processing the output to the computing entity  10 . 
     In various embodiments, the one or more laser sources  60  are configured to generate laser beams and provide the laser beams to the cryogenic chamber  40  (and/or the action chamber  432 ) via one or more optical fibers  64  (e.g.,  64 A,  64 B,  64 C), such that laser beams are accurately and precisely delivered to qubit ions within the ion trap  50  (e.g., precisely in terms of position, frequency, and/or phase). In various embodiments, the optical fibers  64  and/or other optical path and/or wave guide may provide the laser beams to the ion trap  50  and/or action chamber  432  via one or more access openings  446  and/or shield openings  406 ,  416 ,  426  (See  FIGS. 2-7 ). 
     Exemplary Cryogenic Chamber 
       FIGS. 2-4 and 8  provide various views of a cryogenic chamber  40  and  FIGS. 5-7  provide various views of outer and intermediate shields  412 ,  422  (e.g.,  422 A,  422 B). In various embodiments, the cryogenic chamber  40  comprises an interior housing  434  and an outer housing  440 . In various embodiments, the interior housing  430  comprises housing walls  434 . The housing walls  434  define an action chamber  432 . In various embodiments, one or more actions may be performed within the action chamber at a corresponding action temperature. For example, the actions may include performing an experiment, a controlled state evolution, a chemical reaction, performing a function, and/or the like. In an example embodiment, the ion trap  50  of an ion trapped quantum computer  110  is disposed within the action chamber  432 . In various embodiments, the outer housing  440  defines a main chamber  442 . The interior housing  430  and the action chamber  432  are disposed within the main chamber  442 . In various embodiments, the interior housing  430  and/or the outer housing  440  are made of metal. For example, the interior housing  430  and/or the outer housing  440  may be made of copper. 
     The cryogenic chamber is coupled to a cryogenic system configured to maintain the action chamber  432  and/or the interior housing  430  at an action temperature. When the action chamber  432  is maintained at the action temperature the outer housing  440  is maintained at a second temperature. In various embodiments, the action temperatures are cryogenic temperatures (e.g., within the range of 0 K to 124 K). In an example embodiment, the action temperature is approximately 4 K. In an example embodiment, the second temperature is 40 K. 
     In various embodiments, the inner housing  430  and/or the outer housing  440  comprise access openings  436 ,  446 . In various embodiments, the access openings  436 ,  446  allow for laser beams to enter the main chamber  442  and/or the action chamber  432 ; fiber optics and/or electrical cables (e.g.,  46 A,  46 B,  46 C) to provide laser beams, electrical signals, and/or the like to the inside of main chamber  442  and/or the action chamber  432 ; and/or the like. In various embodiments, the access openings  436 ,  446  may be enclosed by a transparent (e.g., transparent at the wavelength of a laser beam being provided to the main chamber and/or action chamber) and/or translucent window  437 ,  448 . 
     In various embodiments, the cryogenic chamber  40  is configured to insulate the action chamber  432  such that the action chamber  432  may be maintained at the action temperature by the cryogenic system  45 . In various embodiments, the cryogenic chamber  40  is configured to seal the main chamber  442  and/or action chamber  432  from the external environment that is exterior to the cryogenic chamber  40  such that the pressure within the main chamber  442  and/or action chamber  432  may be controlled independently of the external environment. For example, the cryogenic chamber  40  may be a vacuum chamber. 
     In various embodiments, the cryogenic chamber  40  comprises a shield  400 . The shield  400  is configured to cause the magnetic field within the action chamber  432  to have very few and/or very small fluctuations such that the magnetic field within the action chamber  432  is highly uniform and/or homogenous. In various embodiments, the shield  400  comprises an interior shield  402 . In various embodiments, the shield  400  may further comprise and exterior shield  412  and/or one or more intermediate shields  422  (e.g.,  422 A,  422 B). In an example embodiment, the shield  400  may further comprise an end shield  404 . In various embodiments, each of the interior shield  402 , exterior shield  412 , and/or one or more intermediate shields is generally a cylindrical shell. The end shield  404  encloses one end of the cylindrical shell of the interior shell  402 . For example, the end shield  404  may be disposed at one end of the cylindrical shell of the interior shell  402  and may be at least partially sandwiched between one or more layers of the end wall of the interior housing  232 , in an example embodiment. 
     In various embodiments, the action chamber  432  is defined by an interior housing  430  of the cryogenic chamber  40 . For example, the interior housing  432  may be disposed within the main chamber  442  of the cryogenic chamber  40 . The interior housing  430  may comprise housing walls  434  that define the action chamber  432  within the interior housing  430 . In various embodiments, the shield  400  comprises an interior shield  402  that is at least partially embedded within the housing walls  434  of the interior housing  430 . For example, at least some of the housing walls  434  of the interior housing  430  may comprise an exterior wall portion  434 B and an interior wall portion  434 A. At least a portion of the interior shield  402  may be sandwiched and/or disposed between the exterior wall portion  434 B and the interior wall portion,  434 A in an example embodiment. 
     In an example embodiment, the housing walls  434  define a first hollow cylinder enclosed at both ends. In an example embodiment, the diameter of the first hollow cylinder is greater than the length of the first hollow cylinder. In an example embodiment, the housing walls  434  that enclose the ends of the first hollow cylinder comprise an exterior wall portion  434 B and an interior wall portion  434 A, where the interior wall portion  434 A faces the action chamber  432  and the exterior wall portion  434 B faces out into the main chamber  442 . In various embodiments, the interior shield  402  also generally defines a second hollow cylinder enclosed at both ends. The portions of the interior shield  402  that enclose the ends of the second hollow cylinder are embedded, sandwiched, and/or disposed between the interior wall portion  434 A and the exterior wall portion  434 B that enclose the ends of the first hollow cylinder of the interior housing  430 . In an example embodiment, the cylinder portion of the second hollow cylinder lines the housing walls  434  of the cylinder portion of the first hollow cylinder facing into the action chamber  432 . In various embodiments, the portions of the interior shield  402  that enclose the ends of the second hollow cylinder and the cylinder portion of the interior shield  402  are in direct electrical communication with each other. For example, the portions of the interior shield  402  that enclose the ends of the second hollow cylinder and the cylinder portion of the interior shield  402  may be made of a continuous piece of material and/or made of multiple pieces of the same material and in direct physical connection with one another. For example, a portion of the interior shield  402  that encloses an end of the second hollow cylinder may abut and/or be in direct physical contact with the cylinder portion of the interior shield  402 . 
     In various embodiments, the interior shield  402  comprises one or more sheets of one or more first materials. For example, one or more sheets of the first materials may be used to form the hollow cylinder portion and the end enclosing portions of the interior shield  402 . In various embodiments, the first materials are metals, metal alloys, and/or the like. In various embodiments, the interior shield  402  is made of a first material that has low resistivity at the action temperature. As used herein the term low resistivity refers to a resistivity of less than approximately 6×10 −8  ohm·m. In an example embodiment, the term low resistivity refers to a resistivity of less than approximately 2.8×10 −8  ohm·m. In an example embodiment, the term low resistivity refers to a resistivity of less than approximately 1.0×10 −8  ohm·m. In an example embodiment, a material with low resistivity may have a resistivity that is less than approximately 5×10 −9  ohm·m. In various embodiments, the interior shield  402  is made of a first material that has low resistivity at the action temperature. In various embodiments, the interior shield  402  is made of a first material that is a superconductor at the action temperature. As used herein the term superconductor refers to a resistivity of approximately zero. For example, the interior shield  402  may comprise one or more layers of a first material that has low resistivity and/or is a super conductor at the action temperature. For example, in an example embodiment, the action temperature is a cryogenic temperature (e.g., less than approximately 124 K). In various embodiments, the first materials may comprise one of and/or a combination of one or more of Al, Bi, Cd, Diamond:B, Ga, Hf, α-Hg, β-Hg, In, Ir, α-La, β-La, Li, Mo, Nb, Os, Pa, Pb, Re, Rh, Ru, Si:B, Sn, Ta, Tc, α-Th, Ti, Tl, α-U, β-U, V, α-W, β-W, Zn, Zr, Ba 8 Si 46 , C 6 Ca, C 6 Li 3 Ca 2 , C 8 K, C 8 KHg, C 6 K, C 3 K, C 3 Li, C 2 Li, C 3 Na, C 2 Na, C 8 Rb, C 6 Sr, C 6 Yb, C 60 Cs 2 Rb, C 60 Cs 2 Rb, C 60 RbX, FeB 4 , InN, In 2 O 3 , LaB 6 , MgB 2 , Nb 3 A 1 , Nb 3 Ge, NbO, NbN, Nb 3 Sn, NbTi, SiC:B, SiC:Al, TiN, V 3 Si, YB 6 , ZrN, ZrB 12 , YBCO, GdBCO, BSCCO, HBCCO (HgBa 2 Ca 2 Cu 3 O x ), SmFeAs(O,F), CeFeAs(O,F), LaFeAs(O,F)), LaFePO, FeSe, (Ba,K)Fe 2 As 2 , NaFeAs, ReBCO, and/or other super conducting materials. 
     In an example embodiment, the interior housing  430  is assembled with the interior shield  402  sandwiched therein. For example, the interior shield  402  may be at least partially sandwiched between layers of the interior housing  430 . In an example, embodiment, the interior shield  402  is annealed and/or heat-treated after the fabrication thereof. The interior housing  430  may then be assembled (e.g., using one or more fasteners) with the interior shield  402  embedded therein. 
     In various embodiments, one end of the interior shield  402  is enclosed at least in part by an end shield  404 . In various embodiments, the end shield  404  is generally planar. The interior shield  402  may comprise a hollow cylindrical portion that is sandwiched, at least in part, within layers of the walls of the interior housing  430 . In an example embodiment, the interior shield  402  may further comprise an end shield  404  that encloses one end of the how cylindrical portion of the interior shield  402 . In an example embodiment, the end shield  404  may also be sandwiched, at least in part, between layers of the walls of the interior housing  430 . In various embodiments, the end shield  404  may include one or more support openings  421  configured to allow support legs  42  to pass therethrough. In various embodiments, the end shield  424  may include a central opening  423  configured to provide optical access to the interior of the interior housing  430 . 
     In various embodiments, the cryogenic chamber  40  comprises an outer housing  440  that defines a main chamber  442  of the cryogenic chamber  40 . For example, the interior housing  430  and the action chamber  432  are disposed within the main chamber  442  of the cryogenic chamber  40 . In various embodiments, an exterior shield  412  is disposed outside of the outer housing  440 . For example, the exterior shield  412  may comprise one or more sheets of a second material that dads the outer surface  441  of the outer housing  440 . For example, the exterior shield  412  may generally define a cylindrical shell that is disposed on the outer surface  441  of the outer housing  440 . For example, the exterior shield  412  may be secured to the outer surface  441  of the outer housing  440 . 
     In various embodiments, the exterior shield  412  is made of one or more second materials (e.g., one or more sheets of the second material(s)). In various embodiments, the second material(s) comprise a metal, metal alloy, and/or other low resistivity material and/or a thermally conductive material. In various embodiments, the exterior shield  412  may comprise at least one thermally conductive layer and at least one low resistivity layer. The thermally conductive layer(s) and the low resistivity layer(s) may be made of different materials. In various embodiments, the second material may be different from the first material of the interior shield  402 . In various embodiments, the exterior shield  412  is expected to be at an outer shield temperature when the action chamber  432  is maintained at the action temperature (e.g., by the cryogenic system  45 ). In various embodiments, the second material has a low resistivity, and/or is a superconductor at the outer shield temperature. In an example embodiment, the outer shield temperature is in the range of approximately 30-100K. In an example embodiment, the outer shield temperature is approximately 40 K. 
     In various embodiments, one or more intermediate shields  422  (e.g.,  422 A,  422 B) may be disposed between the outer housing  440  and the interior housing  430 . For example, an intermediate shield  422  may be disposed within the main chamber  442  and outside of the interior housing  430 . In an example embodiment, two intermediate shields  422 A,  422 B are disposed between the outer housing  440  and the interior housing  430 . In an example embodiment, the at least one of the intermediate shields  422 B is not in direct contact with the outer housing  440  and/or interior housing  430 . For example, the intermediate shield  422 B may be secured to the outer housing  440 , interior housing  430 , and/or another intermediate shield  422 A via one or more spacers  450 . In an example embodiment, two or more intermediate shields  422 A,  422 B may indirect contact with one another via one or more spacers  450 . In an example embodiment, mechanical fasteners  452  are used to secure the spacers  450  to the exterior shield  412 , intermediate shield(s)  422 , and/or outer housing  440 . In an example embodiment, one of the intermediate shields  422 B is secured directly to the interior surface (e.g., the main chamber  442  facing surface) of the outer housing  440 . For example, one of the intermediate shields  422 B dads the interior surface of the hollow cylinder defined by the outer housing  440 . 
     In various embodiments, the intermediate shields  422  each generally define a hollow cylinder. In various embodiments, the intermediate shield(s)  422  comprise one or more sheets of a third material. The third material(s) may be a metal, metal alloy, and/or other low resistivity material and/or a thermally conductive material. In various embodiments, the exterior shield  412  may comprise at least one thermally conductive layer and at least one low resistivity layer. The thermally conductive layer(s) and the low resistivity layer(s) may be made of different materials. In various embodiments, at least one of the third material(s) may be different from the first material(s) of the interior shield and/or the second material(s) of the outer shield. In various embodiments, an intermediate shield  422  is expected to be at an intermediate temperature when the action chamber is maintained at the action temperature (e.g., by the cryogenic system  45 ). In various embodiments, one of the third materials has a low resistivity and/or is a superconductor at the intermediate temperature. In an example embodiment, the intermediate temperature is in the range of approximately 30-100K. In an example embodiment, the intermediate temperature is approximately 40 K. 
     In various embodiments, the first, second, and/or third materials may comprise mumetal or other magnetic shield alloy (e.g., a metal alloy having a high magnetic permeability). In various embodiments, the first, second, and/or third materials may comprise a heat-treated mumetal or other magnetic shield alloy (e.g., a metal alloy having a high magnetic permeability). 
     In various embodiments, the interior shield  402 , exterior shield  412 , and one or more intermediate shields  422  each define a hollow cylinder. In various embodiments, the hollow cylinders of each of the interior shield  402 , exterior shield  412 , and one or more intermediate shields  422  are coaxial. For example, in a cross-section of the shield  400  taken substantially perpendicular to any of an axis defined by the interior shield  402 , an axis defined by the exterior shield  412 , and/or an axis defined by an intermediate shield  422  (and/or top view of the shield  400 , as shown, for example, in  FIG. 6 ) a cross-section of the interior shield, a cross-section of the exterior shield  412 , and a cross-section of the intermediate shield(s)  422  are concentric. 
     In various embodiments, the interior housing  430  and outer housing  440  include or more access openings  436 ,  446 . In various embodiments, the access openings  436 ,  446  may provide an optical path for a laser beam to enter the action chamber  432  for use in the action, provide an optical path for photons generated during the action to leave the action chamber  432 , permit a fiber optic or electrical cable to pass through the outer and/or interior housing  440 ,  430 , and/or the like. In various embodiments, the interior, outer, and/or intermediate shields  402 ,  412 ,  422  comprise shield openings  406 ,  416 ,  426  corresponding to access openings  436 ,  446 . For example, the interior shield  402  comprises a shield opening  406  corresponding to each access opening  436  of the interior housing  430 . For example, the exterior shield  412  comprises a shield opening  416  corresponding to each access opening  446  of the outer housing  440 . In various embodiments, an intermediate shield  422  may comprise a shield opening  426  corresponding to each access opening of the interior and/or outer housing  430 ,  440 . In an example embodiment, the interior shield  402 , intermediate shield  422 , and/or exterior shield  412  comprises a tube stub  408 ,  418  extending outward from the shield opening  406 ,  416 ,  426 . For example, a tube stub  408 ,  418  may be hollow cylinder having substantially the same diameter as the corresponding shield opening  406 ,  416 ,  426 . The tube stub  408 ,  418  may be secured to the corresponding shield (e.g., interior shield  402  and/or exterior shield  418 ) at the perimeter of the shield opening  406 ,  416  and extend outward for a tube length. In various embodiments, the tube stub  408 ,  418  defines a tube diameter. The tube length may be at least approximately three times the tube diameter. In an example embodiment, the tube length may be determined based on other components of the system that are in the vicinity of the shield opening  406 ,  416 ,  426 . For example, the tube stub  408 ,  418  may have a tube length configured to permit optical components to be able to provide an optical signal into the action chamber  432  via the shield opening  406 ,  416 ,  426 . In various embodiments, a tube stub  408 ,  418  is made of the same material as the corresponding shield. 
     In an example embodiment, it may be desired to maintain a particular magnetic field within at least a portion of the action chamber  432 . In various embodiments, Helmholtz/drive coils, permanent magnets, shim coils, and/or the like are disposed outside of the cryogenic chamber  40 . Thus, heat generated by the Helmholtz/drive coils, shim coils, and/or the like does not affect the temperature within the main chamber  442  and/or the action chamber  432  as the heat may be dissipated into the environment outside of the cryogenic chamber  40 . 
     In an example embodiment, Helmholtz/drive coils, permanent magnets, shim coils, and/or the like are disposed within the main chamber  442  (but exterior to the action chamber  432 ). In such an example embodiment, the Helmholtz/drive coils, permanent magnets, shim coils, and/or the like are expected to be at a third temperature when the action chamber  432  is maintained at the action temperature. In various embodiments, the Helmholtz/drive coils, shim coils, and/or the like may be made of and/or comprise a material that has low resistivity and/or acts as a superconductor at the outer shield temperature, intermediate temperature, and/or action temperature. 
     As shown in  FIG. 8 , in an example embodiment, Helmholtz/drive coils  462 , permanent magnets, shim coils  464 , and/or the like are disposed within the action chamber  432 . In such an example embodiment, the Helmholtz/drive coils, permanent magnets, shim coils, and/or the like are expected to be at the action temperature when the action chamber  432  is maintained at the action temperature. In various embodiments, the Helmholtz/drive coils  462 , shim coils  464 , and/or the like may be made of and/or comprise a material that has low resistivity and/or acts as a superconductor at the action temperature. For example, if the Helmholtz/drive coils  462 , shim coils  464 , and/or the like comprise and/or are made of a material (e.g., the first material, in an example embodiment) that acts as a superconductor at the action temperature, the Helmholtz/drive coils  462 , shim coils  464 , and/or the like will generate very little to no heat during operation (e.g., because the resistivity of the Helmholtz/drive coils and/or shim coils will be approximately zero). Thus, operation of the Helmholtz/drive coils  462 , shim coils  464 , and/or the like will not cause significant heating within the action chamber  432 . This allows for the desired magnetic field for the action chamber  432  to be generated within the action chamber  432  (e.g., within the interior shield  402 ), which results in a very precise, highly uniform magnetic field region within the action chamber  432 . 
     Technical Advantages 
     Various embodiments provide technical solutions to the technical problem of maintaining a region within a cryogenic chamber that has a very uniform and/or homogenous magnetic field. In various embodiments, the technical solution for providing a region having a highly uniform and/or homogenous magnetic field includes incorporating a shield  400  into the cryogenic chamber  40  to shield an action chamber  432  and/or main chamber  442  of the cryogenic chamber  40  from stray magnetic fields, fluctuations in magnetic fields in the environment outside of the cryogenic chamber  40 , and/or the like. In various embodiments, the shield  400  comprises an interior shield  402  at least partially embedded within the housing walls  434  of the interior housing  430  of a cryogenic chamber  40 . For example, at least a portion of the interior shield  402  may be sandwiched and/or disposed between the exterior wall portion  434 B and the interior wall portion  434 A of the interior housing  430 . In an example embodiment, a portion of the interior shield  402  is disposed on and/or abutting a face of the housing wall  434  that faces into the action chamber  432 . For example, the housing walls  434  may define a hollow cylinder enclosed on the ends. The interior shield  402  may be sandwiched and/or disposed between the exterior wall portion  434 B and the interior wall portion  434 A of the interior housing  430  on the enclosing ends and disposed on the action-chamber- 432 -facing side of the housing wall  434  on the how cylinder portion of the interior housing  430 . This positioning of the interior shield  402  ensures that the interior shield will be maintained at the action temperature when the action chamber  432  is maintained at the action temperature. In various embodiments, the interior shield  402  is made of one or more first materials and at least one of the first materials has a low resistivity and/or is a superconductor at the action temperature. Thus, the interior shield  402  provides very high quality magnetic field shielding for the action chamber  432 . 
     In various embodiments, the shield  400  further comprises an exterior shield  412  and/or one or more intermediate shields  422 . In various embodiments, the interior shield  402  comprises one or more tube stubs  408  about a shield opening  406  therein. In various embodiments, the exterior shield  412  and/or the intermediate shield  422  comprises one or more tube stubs  418  about a shield opening  416 ,  426  therein. The tube stubs  408 ,  418  act to control, shield, and/or condition the magnetic field in the vicinity of the shield openings  406 ,  416 ,  426  so as to diminish and/or minimize the disruption to the shielding abilities of the interior shield  402 , exterior shield  412 , and/or intermediate shield(s)  422  caused by the shield openings  406 ,  416 ,  426 . 
     Thus, various embodiments provide a shield  400  that is configured to provide a very homogenous magnetic field region within the action chamber  432 . For example, the shield  400  may be configured to reduce, diminish, and/or minimize magnetic field fluctuations within the action chamber  432 . The ability to have the Helmholtz/drive coils  462 , shim coils  464 , and/or the like within the action chamber  432  (e.g., inside the interior shell  402 ) further allows for a highly precise and uniform magnetic field region to be established and/or maintained within the action chamber  432 , without having a significant effect on the temperature within the action chamber  432 . 
     Exemplary Controller 
     In various embodiments, the controller  30  may comprise various controller elements including processing elements, memory, driver controller elements, analog-digital converter elements, and/or the like. For example, the processing elements may comprise programmable logic devices (CPLDs), microprocessors, coprocessing entities, application-specific instruction-set processors (ASIPs), integrated circuits, application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), programmable logic arrays (PLAs), hardware accelerators, other processing devices and/or circuitry, and/or the like. and/or controllers. The term circuitry may refer to an entirely hardware embodiment or a combination of hardware and computer program products. For example, the memory may comprise non-transitory memory such as volatile and/or non-volatile memory storage such as one or more of as hard disks, ROM, PROM, EPROM, EEPROM, flash memory, MMCs, SD memory cards, Memory Sticks, CBRAM, PRAM, FeRAM, RRAM, SONOS, racetrack memory, RAM, DRAM, SRAM, FPM DRAM, EDO DRAM, SDRAM, DDR SDRAM, DDR2 SDRAM, DDR3 SDRAM, RDRAM, RIMM, DIMM, SIMM, VRAM, cache memory, register memory, and/or the like. In various embodiments, the driver controller elements may include one or more drivers and/or controller elements each configured to control one or more drivers. 
     In various embodiments the drivers may be laser drivers; vacuum component drivers; drivers for controlling the flow of current and/or voltage applied to DC, RD, and/or other electrodes used for maintaining and/or controlling the ion trapping potential of the ion trap  50 ; cryogenic system component drivers; and/or the like. In various embodiments, the controller  30  comprises means for communicating and/or receiving signals from one or more optical receiver components such as cameras, MEMs cameras, CCD cameras, photodiodes, photomultiplier tubes, and/or the like. For example, the controller  30  may comprise one or more analog-digital converter elements configured to receive signals from one or more optical receiver components. In various embodiments, the controller  30  may comprise means for receiving executable instructions, command sets, and/or the like from the computing entity  10  and providing output received from the quantum computer  110  (e.g., from an optical collection system) and/or the result of a processing the output to the computing entity  10 . In various embodiments, the computing entity  10  and the controller  30  may communicate via a direct wired and/or wireless connection and/or one or more wired and/or wireless networks  120 . 
     Exemplary Computing Entity 
       FIG. 9  provides an illustrative schematic representative of an example computing entity  10  that can be used in conjunction with embodiments of the present invention. In various embodiments, a computing entity  10  is configured to allow a user to provide input to the quantum computer system  100  (e.g., via a user interface of the computing entity  10 ) and receive, view, and/or the like output from the quantum computer system  100 . 
     As shown in  FIG. 9 , a computing entity  10  can include an antenna  312 , a transmitter  304  (e.g., radio), a receiver  306  (e.g., radio), and a processing element  308  that provides signals to and receives signals from the transmitter  304  and receiver  306 , respectively. The signals provided to and received from the transmitter  304  and the receiver  306 , respectively, may include signaling information/data in accordance with an air interface standard of applicable wireless systems to communicate with various entities, such as a controller  30 , other computing entities  10 , and/or the like. In this regard, the computing entity  10  may be capable of operating with one or more air interface standards, communication protocols, modulation types, and access types. For example, the computing entity  10  may be configured to receive and/or provide communications using a wired data transmission protocol, such as fiber distributed data interface (FDDI), digital subscriber line (DSL), Ethernet, asynchronous transfer mode (ATM), frame relay, data over cable service interface specification (DOCSIS), or any other wired transmission protocol. Similarly, the computing entity  10  may be configured to communicate via wireless external communication networks using any of a variety of protocols, such as general packet radio service (GPRS), Universal Mobile Telecommunications System (UMTS), Code Division Multiple Access 2000 (CDMA2000), CDMA2000 1x (1xRTT), Wideband Code Division Multiple Access (WCDMA), Global System for Mobile Communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), Time Division-Synchronous Code Division Multiple Access (TD-SCDMA), Long Term Evolution (LTE), Evolved Universal Terrestrial Radio Access Network (E-UTRAN), Evolution-Data Optimized (EVDO), High Speed Packet Access (HSPA), High-Speed Downlink Packet Access (HSDPA), IEEE 802.11 (Wi-Fi), Wi-Fi Direct, 802.16 (WiMAX), ultra wideband (UWB), infrared (IR) protocols, near field communication (NFC) protocols, Wibree, Bluetooth protocols, wireless universal serial bus (USB) protocols, and/or any other wireless protocol. The system computing entity  20  may use such protocols and standards to communicate using Border Gateway Protocol (BGP), Dynamic Host Configuration Protocol (DHCP), Domain Name System (DNS), File Transfer Protocol (FTP), Hypertext Transfer Protocol (HTTP), HTTP over TLS/SSL/Secure, Internet Message Access Protocol (IMAP), Network Time Protocol (NTP), Simple Mail Transfer Protocol (SMTP), Telnet, Transport Layer Security (TLS), Secure Sockets Layer (SSL), Internet Protocol (IP), Transmission Control Protocol (TCP), User Datagram Protocol (UDP), Datagram Congestion Control Protocol (DCCP), Stream Control Transmission Protocol (SCTP), HyperText Markup Language (HTML), and/or the like. 
     Via these communication standards and protocols, the computing entity  10  can communicate with various other entities using concepts such as Unstructured Supplementary Service information/data (USSD), Short Message Service (SMS), Multimedia Messaging Service (MMS), Dual-Tone Multi-Frequency Signaling (DTMF), and/or Subscriber Identity Module Dialer (SIM dialer). The computing entity  10  can also download changes, add-ons, and updates, for instance, to its firmware, software (e.g., including executable instructions, applications, program modules), and operating system. 
     The computing entity  10  may also comprise a user interface device comprising one or more user input/output interfaces (e.g., a display  316  and/or speaker/speaker driver coupled to a processing element  308  and a touch screen, keyboard, mouse, and/or microphone coupled to a processing element  308 ). For instance, the user output interface may be configured to provide an application, browser, user interface, interface, dashboard, screen, webpage, page, and/or similar words used herein interchangeably executing on and/or accessible via the computing entity  10  to cause display or audible presentation of information/data and for interaction therewith via one or more user input interfaces. The user input interface can comprise any of a number of devices allowing the computing entity  10  to receive data, such as a keypad  318  (hard or soft), a touch display, voice/speech or motion interfaces, scanners, readers, or other input device. In embodiments including a keypad  318 , the keypad  318  can include (or cause display of) the conventional numeric (0-9) and related keys (#, *), and other keys used for operating the computing entity  10  and may include a full set of alphabetic keys or set of keys that may be activated to provide a full set of alphanumeric keys. In addition to providing input, the user input interface can be used, for example, to activate or deactivate certain functions, such as screen savers and/or sleep modes. Through such inputs the computing entity  10  can collect information/data, user interaction/input, and/or the like. 
     The computing entity  10  can also include volatile storage or memory  322  and/or non-volatile storage or memory  324 , which can be embedded and/or may be removable. For instance, the non-volatile memory may be ROM, PROM, EPROM, EEPROM, flash memory, MMCs, SD memory cards, Memory Sticks, CBRAM, PRAM, FeRAM, RRAM, SONOS, racetrack memory, and/or the like. The volatile memory may be RAM, DRAM, SRAM, FPM DRAM, EDO DRAM, SDRAM, DDR SDRAM, DDR2 SDRAM, DDR3 SDRAM, RDRAM, RIMM, DIMM, SIMM, VRAM, cache memory, register memory, and/or the like. The volatile and non-volatile storage or memory can store databases, database instances, database management system entities, data, applications, programs, program modules, scripts, source code, object code, byte code, compiled code, interpreted code, machine code, executable instructions, and/or the like to implement the functions of the computing entity  10 . 
     CONCLUSION 
     Many modifications and other embodiments of the invention set forth herein will come to mind to one skilled in the art to which the invention pertains having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the invention is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.