A fluxonium qubit (400, 2106, 2108, 2110), comprising: a superinductor (100, 132, 200, 300, 330, 400, 2032), comprising: a substrate (102, 328, 404, 600, 700, 1500, 1900); a first vertical stack (104, 204, 302, 332, 406, 1318, 1918) extending in a vertical direction from a surface (106, 408) of the substrate (102, 328, 404, 600, 700, 1500, 1900), the first vertical stack (104, 204, 302, 332, 406, 1318, 1918) comprising a first Josephson junction (108, 336, 410) and a second Josephson junction (110, 338, 412) connected in series along the vertical direction; a second vertical stack (112, 206, 304, 334, 414, 1320, 1920) extending in the vertical direction from the surface (106, 408) of the substrate (102, 328, 404, 600, 700, 1500, 1900) and spaced apart from the first vertical stack (104, 204, 302, 332, 406, 1318, 1918), the second vertical stack (112, 206, 304, 334, 414, 1320, 1920) comprising a third Josephson junction (114, 340, 412); and a superconducting connector (118, 326, 352, 354) connecting the first and second vertical stacks (104, 204, 302, 332, 406, 1318, 1918; 112, 206, 304, 334, 414, 1320, 1920) in series such that the first, second, and third Josephson junctions (108, 336, 410; 110, 338, 412; 114, 340, 416) are connected in series; and a shunted Josephson junction connected to the superinductor (100, 132, 200, 300, 330, 400, 2032) with superconducting wires (424, 426) such that the first, second, and third Josephson junctions (108, 336, 410; 110, 338, 412; 114, 340, 416) of the superinductor (100, 132, 200, 300, 330, 400, 2032) that are in series are connected in parallel with the shunted Josephson junction, characterised in that the first vertical stack (104, 204, 302, 332, 406, 1318, 1918) and the second vertical stack (112, 206, 304, 334, 414, 1320, 1920) each comprise at least five Josephson junctions (108, 110, 114, 116, 306, 308, 310, 312, 314, 316, 318, 320, 322, 324, 344, 346, 350, 410, 412, 416, 336, 410, 338, 412, 340, 416, 422). a substrate (102, 328, 404, 600, 700, 1500, 1900); a first vertical stack (104, 204, 302, 332, 406, 1318, 1918) extending in a vertical direction from a surface (106, 408) of the substrate (102, 328, 404, 600, 700, 1500, 1900), the first vertical stack (104, 204, 302, 332, 406, 1318, 1918) comprising a first Josephson junction (108, 336, 410) and a second Josephson junction (110, 338, 412) connected in series along the vertical direction; a second vertical stack (112, 206, 304, 334, 414, 1320, 1920) extending in the vertical direction from the surface (106, 408) of the substrate (102, 328, 404, 600, 700, 1500, 1900) and spaced apart from the first vertical stack (104, 204, 302, 332, 406, 1318, 1918), the second vertical stack (112, 206, 304, 334, 414, 1320, 1920) comprising a third Josephson junction (114, 340, 412); and a superconducting connector (118, 326, 352, 354) connecting the first and second vertical stacks (104, 204, 302, 332, 406, 1318, 1918; 112, 206, 304, 334, 414, 1320, 1920) in series such that the first, second, and third Josephson junctions (108, 336, 410; 110, 338, 412; 114, 340, 416) are connected in series; and a shunted Josephson junction connected to the superinductor (100, 132, 200, 300, 330, 400, 2032) with superconducting wires (424, 426) such that the first, second, and third Josephson junctions (108, 336, 410; 110, 338, 412; 114, 340, 416) of the superinductor (100, 132, 200, 300, 330, 400, 2032) that are in series are connected in parallel with the shunted Josephson junction, characterised in that the first vertical stack (104, 204, 302, 332, 406, 1318, 1918) and the second vertical stack (112, 206, 304, 334, 414, 1320, 1920) each comprise at least five Josephson junctions (108, 110, 114, 116, 306, 308, 310, 312, 314, 316, 318, 320, 322, 324, 344, 346, 350, 410, 412, 416, 336, 410, 338, 412, 340, 416, 422).