Flow equations approach to one dimensional quantum Ising model

One dimensional quantum Ising model with nearest neighbor interaction in transverse magnetic field is one of the simplest spin models which undergo quantum phase transition. This model has been precisely solved using different methods. In this paper, we solve this model in uniform magnetic field -Jgσxn precisely using a new method called Continuous Unitary Transformations (CUT) or flow equations, and derive its expectation values <σxn>, <σzn> and <σxnσxn+j>. Then, we apply this method on one dimensional quantum Ising model in staggered magnetic field (-1)nJgσxn. Results show that both models have the same critical properties as expected, and it was also found that spontaneous symmetry breaking cannot be derived from CUT.