# Unitarity in the Schroedinger Formalism of QFT in Curved Space-Time

## TL;DR

This paper reviews scalar field quantization in curved space-time using the Schrödinger formalism, demonstrating that the ground-state is generally unstable and its evolution is non-unitary in semi-classical Bianchi-type I space-times.

## Contribution

It provides a detailed analysis of ground-state instability and non-unitarity in quantum field theory on curved backgrounds within the Schrödinger framework.

## Key findings

- Ground-state norm is time-dependent in Bianchi-type I space-times
- Ground-state evolution is non-unitary in semi-classical curved space-times
- Explicit computation of the ground-state wave functional norm

## Abstract

We review the general quantization of scalar fields in curved space-times in the Schroedinger formalism and discuss the determination of the ground-state. By explicitly computing the norm of the ground-state wave functional, we give an argument for the instability of the ground-state of a QFT in a semi-classical space-time of Bianchi-type I. We find that this norm is, in general, time-dependent, and conclude that the ground-state evolution is not unitary.