arXiv subjects

S. Gherardini

Publications and source records attributed to S. Gherardini.

5 recordsLinked to original sources

arXiv2022

Experimental signature of initial quantum coherence on entropy production

We report the experimental quantification of the contribution to non-equilibrium entropy production that stems from the quantum coherence content in the initial state of a qubit exposed to both coherent driving and dissipation. Our experimental demonstration builds on the exquisite experimental control of the spin state of a nitrogen-vacancy defect in diamond and is underpinned, theoretically, by the formulation of a generalized fluctuation theorem designed to track the effects of quantum coherence. Our results provide significant evidence of the possibility to pinpoint the genuinely quantum mechanical contributions to the thermodynamics of non-equilibrium quantum processes.

quant-ph↗

arXiv2022

Autonomous dissipative Maxwell's demon in a diamond spin qutrit

Engineered dynamical maps combining coherent and dissipative transformations of quantum states with quantum measurements, have demonstrated a number of technological applications, and promise to be a crucial tool in quantum thermodynamic processes. Here, we exploit the control on the effective open spin qutrit dynamics of an NV center, to experimentally realize an autonomous feedback process (Maxwell demon) with tunable dissipative strength. The feedback is enabled by random measurement events that condition the subsequent dissipative evolution of the qutrit. The efficacy of the autonomous Maxwell demon is quantified by experimentally characterizing the fluctuations of the energy exchanged by the system with the environment by means of a generalized Sagawa-Ueda-Tasaki relation for dissipative dynamics. This opens the way to the implementation of a new class of Maxwell demons, which could be useful for quantum sensing and quantum thermodynamic devices.

quant-ph↗

arXiv2021

The role of quantum coherence in energy fluctuations

We discuss the role of quantum coherence in the energy fluctuations of open quantum systems. To this aim, we introduce an operational protocol, to which we refer to as the end-point-measurement scheme, allowing to define the statistics of energy changes as a function of energy measurements performed only after its evolution. At the price of an additional uncertainty on the value of the initial energies, this approach prevents the loss of initial quantum coherences and enables the estimation of their effects on energy fluctuations. We illustrate our findings using a three-level quantum system in interaction with thermal reservoirs.

quant-ph↗

arXiv2021

The role of quantum coherence in energy fluctuations

We discuss the role of quantum coherence in the energy fluctuations of open quantum systems. To this aim, we introduce a protocol, to which we refer to as the end-point-measurement scheme, allowing to define the statistics of energy changes as a function of energy measurements performed only after the evolution of the initial state. At the price of an additional uncertainty on the initial energies, this approach prevents the loss of initial quantum coherences and enables the estimation of their effects on energy fluctuations. We demonstrate our findings by running an experiment on the IBM Quantum Experience superconducting qubit platform.

quant-ph↗

arXiv2019

Characterizing irreversibility in open quantum systems

Irreversibility is a fundamental concept with important implications at many levels. It pinpoints the fundamental difference between the intrinsically reversible microscopic equations of motion and the unidirectional arrow of time that emerges at the macroscopic level. More pragmatically, a full quantification of the degree of irreversibility of a given process can help in the characterisation of the performance of thermo-machines operating at the quantum level. Here, we review the concept of entropy production, which is commonly intended as {\it the} measure of thermodynamic irreversibility of a process, pinpointing the features and shortcomings of its current formulation.

quant-ph↗