Biomolecular machines transduce free energy from one form to another to fulfill many important roles inside cells, with free energy dissipation required to achieve directed progress. We investigate how to break time-reversal symmetry at a given dissipation cost for sawtooth potentials, which have frequently been used to model molecular machines as ratchets. Time asymmetry increases for sawtooth potentials with higher barriers and for driving potentials of intermediate width. We unexpectedly find that symmetric sawtooth potentials maximize time asymmetry, while earlier work examining ratchet models of molecular machines required asymmetric sawtooth potentials -- a distinction related to differences between autonomous and deterministic driving .
Biomolecular machines transduce free energy from one form to another to fulfill many important roles inside cells, with dissipation required to achieve directed progress. We investigate how to break time-reversal symmetry at a given dissipation cost by using deterministic protocols to drive systems over sawtooth potentials, which have frequently been used to model molecular machines as ratchets. Time asymmetry increases for sawtooth potentials with higher barriers and for driving potentials of intermediate width. For systems driven over a sawtooth potential according to a protocol, we find that symmetric sawtooths maximize time asymmetry, while earlier work examining ratchet models of molecular machines required asymmetric sawtooth potentials to achieve directed behavior. This distinction arises because deterministically driven machines are externally provided with direction, while autonomous machines must generate directed behavior .
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For systems driven over a sawtooth potential according to a protocol, we
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sawtooth potentials
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-- a distinction related to differences between autonomous and deterministic driving
to achieve directed behavior. This distinction arises because deterministically driven machines are externally provided with direction, while autonomous machines must generate directed behavior