Order parameter statistics in the critical quantum Ising chain.
The probability distribution of the order parameter is expected to take a universal scaling form at a phase transition. In a spin system at a quantum critical point, this corresponds to universal statistics in the distribution of the total magnetization in the low-lying states. We obtain this scaling function exactly for the ground state and first excited state of the critical quantum Ising spin chain. This is achieved through a remarkable relation to the partition function of the anisotropic Kondo problem, which can be computed by exploiting the integrability of the system.
Department of Physics, University of Virginia, Charlottesville, Virginia 22904-4714 USA.
Austen
A
Lamacraft
Paul
P
Fendley