Thermometric schemes using superposition of temporal order and weak measurement


Speaker:Chiranjib Mukhopadhyay

Title:Thermometric schemes using superposition of temporal order and weak measurement

Time:10:30am.  July 12th,2019

Location:818 Conference Room

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Abstract:

As the minituarization of electronic devices, which are sensitive to temperature, grows apace, sensing of temperature with ever smaller probes is more important than ever. Genuinely quantum mechanical schemes of thermometry are thus expected to be crucial to future technological progress. In this talk, we discuss two such schemes. First 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 also derive a new form of thermodynamic uncertainty relation that is tighter and depends on the energy gap of the probe. Next, we propose a new method to measure the temperature of a bath using the weak measurement scheme with a finite dimensional probe. The precision offered by the present scheme not only shows similar qualitative features as the usual Quantum Fisher Information based thermometric protocols, but also allows for flexibility over setting the optimal thermometric window through judicious choice of post selection measurements.


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