Abstract
Thermal Markovian dynamics is typically obtained by coupling a system to a sufficiently hot bath with a large heat capacity. Here we present a scheme for inducing Markovian dynamics using an arbitrarily small and cold heat bath. The scheme is based on injecting phase noise to the small bath. Markovianity emerges when the dephasing rate is larger than the system-bath coupling. Several unique signatures of small baths are studied. We discuss realizations in ion traps and superconducting qubits and show that it is possible to create an ideal setting where the system dynamics is indifferent to the internal bath dynamics.
Highlights
We suggest a scheme for a bath that generates Markovian dynamics for (1) arbitrary low temperature, and (2) arbitrary small heat capacity
In the limit in which the dephasing rate is much larger than the coupling rate, we show that the microbath induces a Markovian dynamics on the system
We have introduced a paradigm for the implementation of Markovian heat sources with the smallest possible heat capacity
Summary
The fact that the dephased bath can be highly out of equilibrium can be considered as strong systemenvironment coupling effect (in the ATA configuration) This is very different from other strong coupling studies where the interaction dresses the system but the bath is still large [38,39,40,41]. Even though the bath spins in the NN case have almost exactly the same polarizations (figure 2(a)), their correlations with the system differ significantly at 1 a t tMARK as shown by the red curves in figure 2(b) (see the inset for a magnification) This highly interesting correlation equilibration at a rate much slower than the polarization equilibration warrants further study. The unavoidable asymptotic system-bath correlation is another unique feature that appears in small dephased baths, even when the dynamics is fully Markovian.
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