Publication: Non-Abelian Quantum Transport and Thermosqueezing Effects
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American Physical Society
Modern quantum experiments provide examples of transport with noncommuting quantities, offering a tool to understand the interplay between thermal and quantum effects. Here we set forth a theory for nonAbelian transport in the linear response regime. Our key insight is to use generalized Gibbs ensembles with noncommuting charges as the basic building blocks and strict charge-preserving unitaries in a collisional setup. The linear response framework is then built using a collisional model between two reservoirs. We show that the transport coefficients obey Onsager reciprocity. Moreover, we find that quantum coherence, associated with the noncommutativity, acts so as to reduce the net entropy production, when compared to the case of commuting transport. This therefore provides a clear connection between quantum coherent transport and dissipation. As an example, we study heat and squeezing fluxes in bosonic systems, characterizing a set of thermosqueezing coefficients with potential applications in metrology and heat-to-work conversion in the quantum regime.
We thank J.P. Santos for fruitful discussions. The authors acknowledge support from the Abdus Salam International Centre of Theoretical Physics, where part of this work was developed, for both hospitality and financial support. G.M. acknowledges funding from Spanish MICINN through the Juan de la Cierva program (IJC2019-039592I), the European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie Grant Agreement No. 801110, and the Austrian Federal Ministry of Education, Science and Research (BMBWF). J.M.R.P. acknowledges financial support from the Spanish Government (Grant Contract FIS-2017-83706-R) and from the Foundational Questions Institute Fund, a donor-advised fund of Silicon Valley Community Foundation (Grant No. FQXi-IAF19-01). G.T.L. acknowledges the hospitality of Apt. 44, where part of this work was developed, and the financial support of the Sao Paulo Funding Agency FAPESP (Grants No. 2017/50304-7, No. 2017/07973-5, and No. 2018/12813-0) and the Brazilian funding agency CNPq (Grant No. INCT-IQ 246569/2014-0).