Dynamic control of quantum geometric heat flux in a nonequilibrium spin-boson model

Abstract

We study the quantum geometric heat flux in the nonequilibrium spin-boson model. By adopting the noninteracting-blip approximation that is able to accommodate the strong system-bath coupling, we show that there exists a nonzero geometric heat flux only when the two-level system is nondegenerate. Moreover, the pumping, no pumping, and dynamic control of geometric heat flux are discussed in detail, compared to the results with Redfield weak-coupling approximation. In particular, the geometric energy transfer induced by modulation of two system-bath couplings is identified, which is exclusive to quantum transport in the strong system-bath coupling regime.

Unifying quantum heat transfer in a nonequilibrium spin-boson model with full counting statistics

“…(1) under the polaron framework byĤ = U †Ĥ 0Û [9,16,35], where the unitary operator is given bŷ U = e iσ zB /2 , with the collective phononic momentum operator …”

“…From the dynamical control perspective, the timedependent modulation of heat transfer in the NESB model has also attracted tremendous attention, enriching the transfer mechanisms [14][15][16][17][29][30][31][32][33]. The typical realization of the dynamical modulation is the adiabatic quantum pump, which was originally proposed by D. J. Thouless to study the effect of Berry-phase-induced quantization on closed-system transport [34].…”

“…In accordance with the second law of thermodynamics, it is known that heat energy will naturally transfer from a hot source to a cold drain driven by the thermodynamic bias (e.g., temperature), without an external driving field. Considering external modulations, the optimal mechanism of dynamical control can be unraveled in phononic thermal systems [14][15][16][17], even to pump heat against the temperature bias.…”

“…The typical realization of the dynamical modulation is the adiabatic quantum pump, which was originally proposed by D. J. Thouless to study the effect of Berry-phase-induced quantization on closed-system transport [34]. In analogy, as the NESB model is adiabatically and periodically driven by control parameters (e.g., bath temperatures), a geometric-phase-induced heat flow will contribute to the heat transfer [15,16]. However, previous research unraveled the seemingly contradictory results that, in the weak qubit-bath coupling limit, the geometric-phaseinduced heat flux remains finite, independent of the qubit-bath coupling strength under the unbiased condition [15], whereas the counterpart in the strong coupling limit becomes strictly 0 [16].…”

“…In analogy, as the NESB model is adiabatically and periodically driven by control parameters (e.g., bath temperatures), a geometric-phase-induced heat flow will contribute to the heat transfer [15,16]. However, previous research unraveled the seemingly contradictory results that, in the weak qubit-bath coupling limit, the geometric-phaseinduced heat flux remains finite, independent of the qubit-bath coupling strength under the unbiased condition [15], whereas the counterpart in the strong coupling limit becomes strictly 0 [16]. The statement of seemingly contradiction or seemingly contradictory results below has the same meaning as expressed herein by default.…”