Circuit manufacturing method and superconducting circuit
A circuit manufacturing method according to the present disclosure is a circuit manufacturing method by deposition, comprising performing first deposition for forming a first superconductor layer, oxidizing a surface of the first superconductor layer to form an oxide film, performing second deposition for forming a second superconductor layer, whereby a circuit in which Josephson junctions are aligned is generated. A mask includes two opening parts and an odd number of first-type opening parts. The width of a first-type opening part has such a length that the area of a Josephson junction formed based on the first superconductor layer and the second superconductor layer derived from the first-type opening part becomes larger than the area of a Josephson junction formed based on the first superconductor layer and the second superconductor layer derived from the two opening parts that are adjacent to each other.
1 . A superconducting circuit comprising:
a substrate;
first superconductor layers arranged on the substrate in a line shape in a predetermined direction with a predetermined gap therebetween, a surface of each of the first superconductor layers being covered with an oxide film; and
second superconductor layers arranged on the substrate and the first superconductor layers in a line shape in the predetermined direction with the predetermined gap therebetween, the pattern in which the second superconductor layers are arranged being displaced from the pattern in which the first superconductor layers are arranged, wherein
the superconducting circuit include a plurality of Josephson junctions formed by parts where the first superconductor layers and the second superconductor layers overlap each other via the oxide film,
the plurality of Josephson junctions include:
a first Josephson junction having a first area;
a second Josephson junction having a second area;
at least one third Josephson junction each having a third area and between the first Josephson junction and the second Josephson junction; and
a plurality of fourth Josephson junctions each having a fourth area and between the first Josephson junction and the second Josephson junction,
the third area is larger than the fourth area,
the number of the at least one third Josephson junction each having the third area is an odd number and the total number of the at least one third Josephson junction having the third area and the plurality of fourth Josephson junctions each having the fourth area is an odd number as well, and
the superconducting circuit includes a first series circuit in which the at least one third Josephson junction each having the third area and the plurality of fourth Josephson junctions each having the fourth area are connected in series.
2 . The superconducting circuit according to claim 1 , further comprising:
third superconductor layers arranged on the substrate in a line shape in the predetermined direction with the predetermined gap therebetween, a surface of each of the third superconductor layers being covered with an oxide film; and
fourth superconductor layers arranged on the substrate and the third superconductor layers in a line shape in the predetermined direction with the predetermined gap therebetween, the pattern in which the fourth superconductor layers are arranged being displaced from the pattern in which the third superconductor layers are arranged, wherein
the superconducting circuit further include a plurality of Josephson junctions formed by parts where the third superconductor layers and the fourth superconductor layers overlap each other via the oxide film,
the plurality of Josephson junctions formed by parts where the third superconductor layers and the fourth superconductor layers overlap each other via the oxide film include:
a fifth Josephson junction having a fifth area;
a sixth Josephson junction having a sixth area;
at least one seventh Josephson junction each having a seventh area and between the fifth Josephson junction and the sixth Josephson junction; and
a plurality of eighth Josephson junctions each having an eighth area and between the fifth Josephson junction and the sixth Josephson junction,
the seventh area is larger than the eighth area,
the number of the at least one seventh Josephson junction each having the seventh area is an odd number and the total number of the at least one seventh Josephson junction having the seventh area and the plurality of eighth Josephson junctions each having the eighth area is an odd number as well,
the superconducting circuit includes a second series circuit in which the at least one seventh Josephson junction each having the seventh area and the plurality of eighth Josephson junctions each having the eighth area are connected in series, and
the first series circuit and the second series circuit are connected to each other in a loop shape.
3 . The superconducting circuit according to claim 1 , wherein the third area is three or more times larger than the fourth area.