A quantum processor (100, 190) comprising: a plurality of qubit elements (192, 194, 196, 198, 254, 256); a plurality of control members arranged to control the plurality of qubit elements; wherein a quantum state of the qubit elements is encoded in the nuclear or electron spin of one or more donor atoms (104, 184, 604) embedded in a semi conducting structure, characterised by the qubit elements being disposed in a two-dimensional matrix arrangement, and by a control structure comprising: the control members comprising a first set of elongate control members (106, 206, 207), arranged in a first plane above a plane comprising the donor atoms, and a second set of elongate control members (108, 208, 209), arranged in a second plane below the plane comprising the donor atoms; a plurality of control elements disposed on a plane between the first and the second plane, each control element forming a single electron transistor (112, 606) with a respective control member of the first set and a respective control member of the second set, wherein each control member is arranged to control a plurality of qubit elements disposed along a row or a column of the two-dimensional matrix to perform topological quantum error corrected computation, wherein each control member is disposed at intersections or between two rows or columns of donor atoms on a plane above or below a plane comprising the donor atoms, the control members (106, 206, 207) of the first set are parallel to each other and the control members (108, 208, 209) of the second set are parallel to each other; and the control members of the first set are disposed to intersect the control members of the second set to form a plurality of intersections where control members of different sets overlap in the direction perpendicular to the plane comprising the donor atoms (104, 184, 604). a plurality of qubit elements (192, 194, 196, 198, 254, 256); a plurality of control members arranged to control the plurality of qubit elements; wherein a quantum state of the qubit elements is encoded in the nuclear or electron spin of one or more donor atoms (104, 184, 604) embedded in a semi conducting structure, characterised by the qubit elements being disposed in a two-dimensional matrix arrangement, and by a control structure comprising: the control members comprising a first set of elongate control members (106, 206, 207), arranged in a first plane above a plane comprising the donor atoms, and a second set of elongate control members (108, 208, 209), arranged in a second plane below the plane comprising the donor atoms; a plurality of control elements disposed on a plane between the first and the second plane, each control element forming a single electron transistor (112, 606) with a respective control member of the first set and a respective control member of the second set, wherein each control member is arranged to control a plurality of qubit elements disposed along a row or a column of the two-dimensional matrix to perform topological quantum error corrected computation, wherein each control member is disposed at intersections or between two rows or columns of donor atoms on a plane above or below a plane comprising the donor atoms, the control members (106, 206, 207) of the first set are parallel to each other and the control members (108, 208, 209) of the second set are parallel to each other; and the control members of the first set are disposed to intersect the control members of the second set to form a plurality of intersections where control members of different sets overlap in the direction perpendicular to the plane comprising the donor atoms (104, 184, 604). the control members comprising a first set of elongate control members (106, 206, 207), arranged in a first plane above a plane comprising the donor atoms, and a second set of elongate control members (108, 208, 209), arranged in a second plane below the plane comprising the donor atoms; a plurality of control elements disposed on a plane between the first and the second plane, each control element forming a single electron transistor (112, 606) with a respective control member of the first set and a respective control member of the second set, wherein each control member is arranged to control a plurality of qubit elements disposed along a row or a column of the two-dimensional matrix to perform topological quantum error corrected computation, wherein each control member is disposed at intersections or between two rows or columns of donor atoms on a plane above or below a plane comprising the donor atoms, the control members (106, 206, 207) of the first set are parallel to each other and the control members (108, 208, 209) of the second set are parallel to each other; and the control members of the first set are disposed to intersect the control members of the second set to form a plurality of intersections where control members of different sets overlap in the direction perpendicular to the plane comprising the donor atoms (104, 184, 604).