We apply periodic control to realize a quantum thermal transistor, which we term as the Floquet quantum thermal transistor. Periodic modulation allows us to control the heat flows and achieve large amplification factors even for fixed bath temperatures. Importantly, this transistor effect persists in the cutoff region, where traditional quantum thermal transistors operating in the absence of periodic modulation, fail to act as viable heat modulation devices.

We have constructed a unified framework for generalizing the finite-time thermodynamic behavior of statistically distinct bosonic and fermionic Stirling cycles with regenerative characteristics. In our formalism, working fluids consisting of particles obeying Fermi-Dirac and Bose-Einstein statistics are treated on equal footing and modeled as a collection of noninteracting harmonic and fermionic oscillators. In terms of the frequency and population of the two oscillators, we have provided an interesting generalization for the definitions of heat and work that are valid for classical as well as nonclassical working fluids. Based on a generic setting under finite-time relaxation dynamics, nice results on low- and high-temperature heat transfer rates are derived. Characterized by equal power, efficiency, entropy production, cycle time, and coefficient of performance, the thermodynamic equivalence between two types of Stirling cycles is established in the low-temperature “quantum” regime.

In this article, we show that a quantum gas, a collection of massive, non-interacting, indistinguishable quantum particles, can be realized as a thermodynamic machine as an artifact of energy quantization and, hence, bears no classical analog. Such a thermodynamic machine depends on the statistics of the particles, the chemical potential, and the spatial dimension of the system. Our detailed analysis demonstrates the fundamental features of quantum Stirling cycles, from the viewpoint of particle statistics and system dimensions, that helps us to realize desired quantum heat engines and refrigerators by exploiting the role of quantum statistical mechanics. In particular, a clear distinction between the behavior of a Fermi gas and a Bose gas is observed in one dimension, rather than in higher dimensions, solely due to the innate differences in their particle statistics indicating the conspicuous role of a quantum thermodynamic signature in lower dimensions.

We propose a minimal model of a Coulomb-coupled fermionic quantum dot thermal diode that can act as an efficient thermal switch and exhibit complete rectification behavior, even in the presence of a small temperature gradient. Using two well-defined dimensionless system parameters, universal characteristics of the optimal heat current conditions are identified. It is shown to be independent of any system parameter and is obtained only at the mean transitions point “−0.5”, associated with the equilibrium distribution of the two fermionic reservoirs, tacitly referred to as “universal magic mean”.

We introduce a simplified model for a three-terminal quantum thermocouple consisting of two strongly coupled quantum dots. To elucidate spin-dependent Seebeck and Peltier effects, we employ a microscopic Hamiltonian and map the Lindblad master equation onto a quantum transition network, capturing the key working principles for both reciprocal effects. Our analysis reveals quantum thermodynamic networks encompassing both Coulomb interaction and spin-flipping processes, lead to the emergence of spin-thermolectric effects. Using algebraic graph theory, we recover the phenomenological law of irreversible thermodynamics from the stochastic version of the entropy production rate expressed in terms of cycle flux and cycle forces. Remarkably, Onsager reciprocity and Kelvin relation for transport coefficients find their premises in the properties of cycle flux trajectories within the quantum transition network. This underscores the universal generality of thermodynamic principles across classical and quantum realms, despite their fundamentally different basis from classical laws of irreversible thermodynamics relying on local equilibrium assumptions.