Prasanna Venkatesh, Asia Pacific Center for Theoretical Physics
In the first part of the talk I will focus on resonant tunneling and directed transport of ultracold atoms that are strongly coupled to an optical lattice inside a ring-cavity and to which an uniform bias force is applied. The bias force induces Bloch oscillations causing amplitude and phase modulation of the lattice which resonantly modifies the site-to-site tunneling. We show how different aspects of the transport such as the direction and magnitude can be simply controlled by changing the cavity detuning.
In the second part, I will introduce transient work fluctuation theorems, which are some exact relations constraining the statistics of work performed on a system that is driven far out of equilibrium. Such fluctuation theorems have important ramifications for the thermodynamics of biological and artificial devices on the nanoscale and the design of engines that operate in quantum regimes. In quantum systems, experimental verification of fluctuation theorems is still in its nascent stages. Part of the reason for this is that work is not a conventional quantum observable that can be represented by a hermitian operator. The widely accepted definition of quantum work requires two projective measurements of the system's energy before and after the driving protocol is applied. In our work we have examined the effect of replacing projective measurement of energy with generalized measurements. We find a no-go theorem that suggests in general projective measurements are the only universal measurements that can satisfy fluctuation theorems.
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