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arXiv · 1410.1299

Double-Fock Superposition Interferometry for Differential Diagnosis of Decoherence

Malte C. Tichy·Young-Sik Ra·Hyang-Tag Lim·Clemens Gneiting·Yoon-Ho Kim·Klaus Mølmer
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Abstract

Interferometric signals are degraded by decoherence, which encompasses dephasing, mixing and any distinguishing which-path information. These three paradigmatic processes are fundamentally different, but, for coherent, single-photon and $N00N$-states, they degrade interferometric visibility in the very same way, which impedes the diagnosis of the cause for reduced visibility in a single experiment. We introduce a versatile formalism for many-boson interferometry based on double-sided Feynman diagrams, which we apply to a protocol for differential decoherence diagnosis: Twin-Fock states |N,N> with $N \ge 2$ reveal to which extent decoherence is due to path distinguishability or to mixing, while double-Fock superpositions $|N:M> = (|N,M> + |M,N>)/\sqrt{2} $ with $N > M >0$ additionally witness the degree of dephasing. Hence, double-Fock superposition interferometry permits the differential diagnosis of decoherence processes in a single experiment, indispensable for the assessment of interferometers.

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Malte C. Tichy, Young-Sik Ra, Hyang-Tag Lim, Clemens Gneiting, Yoon-Ho Kim, Klaus Mølmer. 2015-01-30. Double-Fock Superposition Interferometry for Differential Diagnosis of Decoherence. https://doi.org/10.1088/1367-2630%2F17%2F2%2F023008

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