Abstract
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 a nitrogen-vacancy center to experimentally realize an autonomous feedback process (Maxwell’s 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's demon is quantified by means of a generalized Sagawa-Ueda-Tasaki relation for dissipative dynamics. To achieve this, we experimentally characterize the fluctuations of the energy exchanged between the system and its the environment. This opens the way to the implementation of a new class of Maxwell’s demons, which could be useful for quantum sensing and quantum thermodynamic devices.
- Received 8 June 2021
- Revised 11 January 2022
- Accepted 7 April 2022
DOI:https://doi.org/10.1103/PRXQuantum.3.020329
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.
Published by the American Physical Society
Physics Subject Headings (PhySH)
Popular Summary
Maxwell demons have revealed the relationship between thermodynamics and information: they are intelligent entities that use the information extracted from a system to condition its dynamics, with results that may be in apparent contrast with thermodynamics laws. The combination of measurement and feedback control is the core of the modern formulation of Maxwell's demons. In quantum settings, their description cannot neglect quantum fluctuations, which become comparable with the relevant energy scales. In its simplest form, a Maxwell demon acts via unitary evolution. Including non-unital operations, such as irreversible dissipation, can be a crucial resource for quantum information and thermodynamics, since they can be used to produce strongly correlated states, or to prepare and stabilize robust phases and entanglement.
Here, we realize an autonomous dissipative Maxwell demon with a spin qutrit formed by a Nitrogen-Vacancy center in diamond at room temperature. The intrinsic feedback mechanism acting on a dissipative dynamics is achieved by performing random projective measurements followed by conditioned and tunable optical pumping. We determine the conditions under which the demon enables the extraction of energy from the system, and we measured the purely quantum (non-thermal) energy fluctuations of the qutrit.
Our work paves the way for the use of Nitrogen-Vacancy centers in diamond to further investigate open quantum system dynamics and thermodynamics, including non-Gibbsian quantum heat engines, the role of coherence in energy exchange mechanisms. More broadly, it opens the possibility for reinterpreting dissipative phenomena as Maxwell demons to shed light on energy-information relations.