  We propose a novel approach to qubit thermometry using a quantum switch, that
introduces an indefinite causal order in the probe-bath interaction, to
significantly enhance the thermometric precision. The resulting qubit probe
shows improved precision in both low and high temperature regimes when compared
to optimal qubit probes studied previously. It even performs better than a
Harmonic oscillator probe, in spite of having only two energy levels rather
than an infinite number of energy levels as that in a harmonic oscillator. We
thereby show unambiguously that quantum resources such as the quantum switch
can significantly improve equilibrium thermometry. We also derive a new form of
thermodynamic uncertainty relation that is tighter and depends on the energy
gap of the probe. The present work may pave the way for using indefinite causal
order as a metrological resource.
