Pre-prints

Andreev spin qubits based on the helical edge states of magnetically doped two-dimensional topological insulators

Edoardo Latini, Fausto Rossi, Fabrizio Dolcini

We show that Andreev spin qubits can be realized in a Josephson junction based on the helical edge states of a two-dimensional topological insulator (quantum spin Hall system) proximized by superconducting films, in the presence of magnetic doping. We demonstrate that the electrical dipole transitions between the Andreev spin states induced by the magnetic doping can be harnessed to optically manipulate the Andreev spin qubit by microwave radiation pulses. We numerically simulate the realization of NOT and Hadamard quantum logic gates, and discuss implementations in realistic setups.

ArXiv:2601.22226

An Information-Theoretic Bound on Thermodynamic Efficiency and the Generalized Carnot's Theorem

Anna Gabetti, Fabrizio Dolcini, Davide Girolami

We derive a bound on the efficiency of thermal engines that can be sharper than Carnot's limit. It is a function of statistical correlations between the engine internal state and Hamiltonian, can be saturated even in finite-time cycles, and applies to both classical and quantum engines. Specifically, the bound establishes the exact maximal efficiency of engines operating with multiple baths, tightening the upper limit set by Carnot's theorem. Then, we show that an engine made of a quantum dot coupled with fermionic baths can achieve the bound, even when operating beyond the quasistatic regime. The result provides a design principle for realistic energy harvesting machines.

ArXiv: 2604.10762