A prescription for holographic Schwinger-Keldysh contour in non-equilibrium systems

Understand

We develop a prescription for computing real-time correlation functions defined on a Schwinger-Keldysh contour for non-equilibrium systems using gravity.

• The prescription involves a new analytic continuation procedure in a black hole geometry which can be dynamical.
• For a system with a slowly varying horizon, the continuation enables computation of the Schwinger-Keldysh generating functional using derivative expansion, drastically simplifying calculations.
• We illustrate the prescription with two-point functions for a scalar operator.