Selected Topics:

Thermoelectric heat engine

Thermodynamics and Information

Self-propelled particle

Vesicles in flow

Membrane Adhesion

Hidden degree of freedom


Biological information processing

ChemotaxisAcquiring and processing information about the instantaneous state of the environment is a prerequisite for the survival of any living system. Sensory and signal transducing networks have evolved in order to achieve this task under a variety of external conditions. Maintaining any biochemical network has, however, a metabolic cost associated with its inherent nonequilibrium nature.
For instance, chemotaxis is the ability of cellular organisms to bias their motion along chemical gradients like food concentrations. They sense external concentrations via receptors located on the cell membrane, transmitting information about the cell exterior to the cell interior to learn more about the environment. We have shown that the amount of information a cell can acquire about its environment is bounded by the thermodynamic cost, allowing to study the efficiency of cellular information processing. Furthermore, we have shown a clear analogy between nonequilibrium sensing and kinetic proofreading, which is a dissipative error-correcting mechanism for biological copying.

Related publications

Nonequilibrium sensing and its analogy to kinetic proofreading
D. Hartich, A. C. Barato, and U. Seifert
New J. Phys. 17, 055026, 2015
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Efficiency of cellular information processing
A. C. Barato, D. Hartich, and U. Seifert
New J. Phys. 16, 103024, 2014
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Information-theoretic vs. thermodynamic entropy production in autonomous sensory networks
A. C. Barato, D. Hartich, and U. Seifert
Phys. Rev. E 87, 042104, 2013
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Feedback-Driven Quantum Engines

Quantum 2-level system with feedbackA genuine feature of projective quantum measurements is that they inevitably alter the mean energy of the observed system if the measured quantity does not commute with the Hamiltonian. Compared to the classical case, this additional energetic cost leads to a stronger bound on the work extractable after a single measurement from a system initially in thermal equilibrium. Here, we extend this bound to a large class of feedback-driven quantum engines operating periodically and in finite time. The bound thus implies a natural definition for the efficiency of information to work conversion in such devices. For a simple model consisting of a laser-driven two-level system, we maximize the efficiency with respect to the observable whose measurement is used to control the feedback operations. We find that the optimal observable typically does not commute with the Hamiltonian and hence  would not be available in a classical two level system. This result reveals that periodic feedback engines operating in the quantum realm can exploit quantum coherences to enhance efficiency.

Related publications

Coherence-enhanced efficiency of feedback-driven quantum engines
K. Brandner, M. Bauer, M. T. Schmid, and U. Seifert
New J. Phys. 17, 065006, 2015
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