Swati Singh, ITAMP, Harvard

The study of the interaction between quantum systems and their environment is central to the understanding of a broad range of problems. Important examples include the elusive quantum to classical transition, as illustrated most famously by the Schrödinger cat paradox, and non-equilibrium dynamics, as illustrated by the central spin problem. On the applied side, this understanding is an essential step towards quantum metrology, including the development of quantum noise limited detectors.

Environments composed of quantum spins are particularly intriguing due to their nonlinear interactions with the system, a result of their inherent quantum nature. Following a general introduction I will illustrate key features of such environments in two simple and experimentally realizable examples: a nitrogen vacancy (NV) center in diamond interacting with its nuclear spin environment, and a single motional mode of a mechanical oscillator interacting with a cloud of spin-1 cold atoms.

In the first case I will demonstrate within a semiclassical description that it is possible to monitor and cool the nuclear spin bath by optically pumping the electronic spin of the NV center. In the second example I will show that by coupling an oscillator to a cloud of cold atoms and manipulating the spin of the atomic ensemble it is possible to cool and manipulate the motional states of a harmonic oscillator.