Heisenberg group

== English == === Etymology === Named after Werner Heisenberg. === Proper noun === the Heisenberg group (mathematics) The group of 3×3 upper triangular matrices of the form ( 1 a c 0 1 b 0 0 1 ) {\displaystyle {\begin{pmatrix}1&a&c\\0&1&b\\0&0&1\\\end{pmatrix}}} under the operation of matrix multiplication, arising in the description of one-dimensional quantum-mechanical systems.