Geometrically and electrically balanaced dc SQUID system having a pair of intersecting slits

A balanced thin film dc SQUID system comprising a substrate, a superconductive groundplane layer on said substrate, said superconductive groundplane layer being formed with a first slit having an enlarged opening at each end thereof, thin film Josephson junction means located on said substrate, said Josephson junction means being part of a SQUID loop, means for interconnecting said Josephson junction means, a thin film signal coil in coupling relationship with each said enlarged opening at opposite ends of said first slit, and means for applying bias current to said Josephson junction means, said system comprising:

• a second slit formed in said superconductive groundplane layer, said second slit forming a mutual intersection with said first slit intermediate their ends, said second slit having an enlarged opening at each end thereof;
• said Josephson junction means being located on diagonally opposite corners of said groundplane at said intersection of said slits;
• said means for interconnecting said Josephson junction means extending across said intersection;
• a pair of thin film modulation coils, each said modulation cell being in coupling relationship with one of said enlarged openings at opposite ends of said second slit;
• and
• a superconducting plate extending over said Josephson junction means and over said intersecting slits;
• said means for applying bias current to said Josephson junction means functioning to apply the bias current symmetrically.

A balanced thin film de SQUID system comprising a substrate, a superconductive groundplane layer on said substrate, said superconductive groundplane layer being formed with a first slit having an enlarged opening at each end thereof, thin film Josephson junction means located on said substrate;

• said Josephson junction means being part of a SQUID loop, means for interconnecting said Josephson junction means, a thin film signal coil in coupling relationship with each said enlarged opening at opposite ends of said slit, and means for applying bias current to said Josephson junction means, said system comprising:
• a second slit formed in said superconductive groundplane layer is formed, said second slit forming a mutual intersection with said first slit intermediate their ends, said second slit having an enlarged opening at each end thereof;
• said Josephson junction means being located on diagonally opposite corners of said groundplane at said intersection of said slits;
• said means for interconnecting said Josephson junctions means extending across said intersection;
• an electrically balanced, physically symmetrical pair of thin film signal coils each said signal coil being in coupling relationship with one of said enlarged openings at opposite ends of said first slit;
• a thin film modulation coil in coupling relationship with each said enlarged opening at opposite ends of said second slit;
• and
• a superconducting plate extending over Josephson junction means and over said intersecting slits;
• the bias current being applied to said Josephson junction means in a way so as to not disturb the symmetry created by said signal coil arrangement.

A balanced thin film de SQUID system comprising a substrate, a superconductive groundplace layer on said substrate, said superconductive groundplane layer being formed with a first slit having an enlarged opening at each end thereof, thin film Josephson junction means located on said substrate said Josephson junction means being part of a squid loop, means for interconnecting said Josephson junction means, a thin film signal coil in coupling relationship with each said enlarged opening at opposite ends of said first slit, and means for applying bias current to said Josephson junction means, said system comprising:

• a second slit formed in said superconductive groundplate layer, said second slit forming a mutual intersection with said first slit intermediate their ends, said second slit having an enlarged opening at each end thereof;
• said Josephson junction means being located on a diagonally opposite corners of said groundplane at said intersection of said slits;
• said means for interconnecting said Josephson junction means extending across intersection;
• an electrically balanced, physically symmetrical pair of thin film signal coils, each said signal coil being in coupling relationship with one of said enlarged openings at opposite ends of said first slit;
• an electrically balanced, physiclaly symmetrical pair of thin film modulation coils each said modulation coil being in coupling relationship with one of said enlarged openings at opposite ends of said second slit, said pair of modulation coils being electrically and physically symmetrical with respect to said signal coils;
• and
• a superconducting plate extending over said Josephson junction means and over said intersecting slits;
• said means for applying bias current to said Josephson junction means functioning to apply the bias current symmetrically so as to enhance the symmetry created by said signal coil and modulation coil arrangement.

A balanced thin film de SQUID system comprising a substrate, a superconductive groundplane layer on said substrate, said superconductive groundplane layer being formed with a first slit having an enlarged opening at each end thereof, thin film Josephson junction means located on said substrate, said Josephson junction means being part of a SQUID loop, means for interconnecting said Josephson junction means, a thin film signal coil in coupling relationship with each said enlarged opening at opposite ends of said first slit, and means for applying bias current to said Josephson junction means, said system comprising:

• a second slit formed in said superconductive groundplane layer, said second slit forming a mutual intersection with said first slit intermediate their ends, said second slit having an enlarged opening at each end thereof;
• said Josephson junction means being located on diagonally opposite corners of said groundplane at said intersection of said slits;
• said means for interconnecting said Josephson junction means extending across said intersection;
• an electrically balanced, physically symmetrical pair of thin modulation coils each said modulation coil being in coupling relationship with one of said enlarged openings at opposite ends of said second slit;
• and
• a restor/capacitor network selectively coupled across each coil of at least one of said pairs of signals coils and modulation coils;
• said signal coils being electrically balanced and physically symmetrical with respect to each other and are physically symmetrical with respect to said modulation coils;
• the bias current being applied to said Josephson junction means in a way so as to not disturb the symmetry created by said modulation coil arrangement.

A balanced thin film de SQUID system comprising a substrate, a superconductive groundplane layer on said substrate, said superconductive groundplane layer being fromed with a first slit an enlarge opening at each end thereof, thin film Josephson junction means located on said substrate, said Josephson junction means being part of a SQUID loop, means for interconnecting said Josephson junction means, a thin film signal coil in coupling relationship with each said enlarged opening at opposite ends of said first slit, and means for applying bias current to said Josephson junction means, said system comprising:

• a second slit formed in said superconductive groundplane layer, said second slit forming a mutual intersection with said first slit intermediate their ends, said second slit having an enlarged opening at each end thereof;
• said Josephson junction means being located on diagonally opposite corners of said groundplane at said intersection of said slits;
• said means for interconnecting said Josephson junction means extending across said intersection;
• a pair of thin film modulation coils each said modulation coil being in coupling relationship with one of said enlarged openings at opposite ends of said second slit;
• and
• a resistor/capacitor network selectively coupled across each coil of at least one of said pairs of signal coils and modulation coils;
• said signal coils being electrically balanced and physically symmetrical with respect to each other and are physically symmetrical with respect to said modulation coils.
• said means for applying bias current to said Josephson junction means functioning to apply the bias currently symmetrically.

A balanced thin film de SQUID system comprising a substrate, a superconductive groundplane layer on said substrate, said superconductive groundplane layer being formed with a first slit having an enlarged opening at each end thereof, thin film Josephson junction means located on said substrate, said Josephson junction means being part of a SQUID loop, means for interconnecting said Josephson junction means, a thin film signal coil in coupling relationship with each said enlarged opening at opposite ends of said slit, and means for applying bias current to said Josephson junction means, said system comprising:

• a second slit formed in said superconductive groundplate layer, said second slit forming a mutual intersection with said first slit intermediate their ends, said second slit having an enlarged opening at each end thereof;
• said Josephson junction means being located on diagonally opposite corners of said groundplate at said intersection of said slits;
• said means for interconnecting said Josephson junctions means extending across said intersection;
• an electrically balanced, physically symmetrical pair of thin film signal coils each said signal coil being in coupling relationship with one of said enlarged openings at opposite ends of said first slit;
• a thin film modulation coil is coupling relationship with each said enlarged opening at opposite ends of said second slit;
• a resistor/capacitor network selectively coupled across each coil of at least one of said pairs of signal coils and modulation coils;
• said modulation coils being electrically balanced and physically symmetrical with respect to each other and are physically symmetrical with respect to said signal coils;
• the bias current being applied to said Josephson junction means in a way so as to not disturb the symmetry created by said signal coil arrangement.

A balanced thin film de SQUID system comprising a substrate, a superconductive groundplane layer on said substrate, said superconductive groundplane layer being formed with a first slit having an enlarged opening at each end thereof, thin film Josephson junction means located on said substrate, said Josephson junction means being part of a SQUID loop, means for interconnecting said Josephson junction means, a thin film signal coil is coupling relationship with each said enlarged opening at opposite ends of said first slit, and means for applying bias current to said Josephson junction means, said system comprising:

• a second slit formed in said superconductive groundplane layer, said second slit forming a mutual intersection with said first slit intermediate their ends, said second slit having an enlarged opening at each end thereof;
• said Josephson junction means being located on diagonally opposite corners of said groundplane at said intersection of said slits;
• said means for interconnecting said Josephson junction means extending across said intersection;
• an electrically balanced, physically symmetrical pair of thin film signal coils each said signal coil being in coupling relationship with one of said enlarged openings at opposite ends of said slit;
• an electrically balanced, physically symmetrical pair of thin film modulation coils each said modulations coil being in coupling relationship with one of said enlarged openings at opposite ends of said second slit, sair pair of modulation coils being electrically and physically symmetrical with respect to said signal coils;
• and
• a resistor/capacitor network selectively coupled across each of at least one of said pairs of signal coils and modulation coils;
• said means for applying bias current to said Josephson junction means functioning to apply the bias current symmetrically so as to enhance the symmetry created by said signal coil and modulation coil arrangement.