Apply the Bravyi-Kitaev transform.
Used in the notebooks
Implementation from arXiv:quant-ph/0003137 and
"A New Data Structure for Cumulative Frequency Tables" by Peter M. Fenwick.
Note that this implementation is equivalent to the one described in
arXiv:1208.5986, and is different from the one described in
arXiv:1701.07072. The one described in arXiv:1701.07072 is implemented
in OpenFermion as
A FermionOperator to transform.
Can force the number of qubits in the resulting operator above the
number that appear in the input operator.
An instance of the QubitOperator class.
Invalid number of qubits specified.