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Minimising the heat dissipation of information erasure

Mohammady, M. ; Mohseni, M. ; Omar, Y.

Minimising the heat dissipation of information erasure, Proc Benasque QI, Benasque, Spain, Vol. N/A, pp. N/A - N/A, June, 2015.

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Landauer’s principle states that reducing the entropy of an object, due to information erasure, must dissipate a minimum quantity of heat to a thermal reservoir. However, it only states that this lower bound of heat dissipation is obtained for some physical situation, but not all; in some situations there is even a limit to how much entropy reduction can be attained. Consequently we develop the concept of minimal heat dissipation given probabilistic information erasure, provided knowledge of the reservoir’s Hamiltonian. Precisely, we determine the unitary operator acting on the composite system of object and reservoir so that the probability of preparing the object in a pure state is brought to a desired value. Subsequently, the unitary operator is optimised to minimise the resulting heat dissipation to the reservoir. We consider two concrete models of maximising the probability of erasing a qubit. Moreover, for these models we investigate the effect of energy conserving, Markovian dephasing on the process of information erasure. Finally, we enumerate the ways in which it is possible to cheat and achieve heat dissipation lower than Landauer’s limit, but in a way that terms such as heat and temperature would remain applicable.