Abstract
Fluctuation theorems (FTs) are central in stochastic thermodynamics, as they allow for quantifying the irreversibility of single trajectories. Although they have been experimentally checked in the classical regime, a practical demonstration in the framework of quantum open systems is still to come. Here we propose a realistic platform to probe FTs in the quantum regime. It is based on an effective two-level system coupled to an engineered reservoir, that enables the detection of the photons emitted and absorbed by the system. When the system is coherently driven, a measurable quantum component in the entropy production is evidenced. We quantify the error due to photon detection inefficiency, and show that the missing information can be efficiently corrected, based solely on the detected events. Our findings provide new insights into how the quantum character of a physical system impacts its thermodynamic evolution.
Highlights
We consider a system whose three levels are denoted by |m, |e and |g of respective energy Em > Ee > Eg
D2) detects the photons emitted at frequency ω1, one can formulate the evolution of the qubit state conditioned to the measurement records of the detectors in terms of quantum jumps
Between two detected photons, there exist several different possible trajectories of pure states, which cannot be distinguished by the measurement record: Each of these trajectories corresponds to a particular sequence of undetected emissions and absorptions
Summary
We consider a system whose three levels are denoted by |m , |e and |g of respective energy Em > Ee > Eg (see Fig.2a). The states |e and |g define our effective qubit of interest (Fig.2b). In what follows we drive the qubit transition with a Hamiltonian Hd(t), such that ω1 may depend on time: the rates Γ± can be adjusted to keep the effective temperature constant. These adjustments are discussed in Ref.[26] and the Methods Section at the end of this manuscript. Assuming an initial known pure state |Ψ0 of the qubit, and discretizing the time between ti and tf such as tn = ti + ndt (with n ∈ 0, N and tN = tf), the evolution of the system features a stochastic trajectory γ of pure states |ψγ(tn). At time tn corresponds to applying the operator M1 = Γ−dtσ
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