Other derivation of (4.68) which could be useful in quantum computing is as follows.
Let $H^p$ the Hilbert space with orthonormal basis $\left\{ |\omega_p> \right\} $. We define a unitary transformation
$$ U : H^p \rightarrow H^p$$
by the formula·
$$ U = (-1)^F b {e}^{-\beta\,H} $$
with
$$ U |\omega_p>= (-1)^p {e}^{-\beta\,E_p} b |\omega_p> $$
Let a quantum state given by
$$|\Psi>= \sum _p|\omega_p>.$$
Will all these ingredients we make the following computation.
$$Tr((-1)^F b {e}^{-\beta\,H} ) = Tr(U)= < \Psi |U|\Psi>= \sum _q\sum _p<\omega_q|U|\omega_p>,$$
$$Tr((-1)^F b {e}^{-\beta\,H} ) = Tr(U)= < \Psi |U|\Psi>=\sum _q\sum _p<\omega_q|(-1)^p {e}^{-\beta\,E_p} b |\omega_p>,$$
$$Tr((-1)^F b {e}^{-\beta\,H} ) = Tr(U)= < \Psi |U|\Psi>=\sum _q\sum _p(-1)^p {e}^{-\beta\,E_p} <\omega_q|b |\omega_p>,$$
$$Tr((-1)^F b {e}^{-\beta\,H} ) = Tr(U)= < \Psi |U|\Psi>=\sum _q\sum _p(-1)^p {e}^{-\beta\,E_p} <\omega_p|b |\omega_p>\delta_{{q,p}},$$
$$Tr((-1)^F b {e}^{-\beta\,H} ) = Tr(U)= < \Psi |U|\Psi>=\sum _p(-1)^p {e}^{-\beta\,E_p} <\omega_p|b |\omega_p>,$$
$$Tr((-1)^F b {e}^{-\beta\,H} ) = Tr(U)= < \Psi |U|\Psi>= \sum _p(-1)^p \chi_{{p}} \left( b \right) = \chi \left( M_{{b}} \right) .$$
Reference : Louis Kauffman, arXiv:1001.0354v3 [math.GT] 31 Jan 2010 Topological Quantum Information, Khovanov Homology and the Jones Polynomial (http://lanl.arxiv.org/pdf/1001.0354)