# Quantum superpositions and entanglement of thermal states at high temperatures and their applications to quantum information processing

## TL;DR

This paper explores how thermal states at high temperatures can exhibit superpositions and entanglement, enabling quantum information tasks like teleportation and gates using thermal-state qubits and Bell states.

## Contribution

It introduces thermal-state qubits and thermal-Bell states, extending pure-state concepts to thermal mixtures, and proposes a scheme for their discrimination without photon number resolving detection.

## Key findings

- Thermal-Bell states can be discriminated using Kerr nonlinear interactions.
- Quantum teleportation can be performed with thermal-state qubits.
- The scheme avoids the need for photon number resolving detectors.

## Abstract

We study characteristics of superpositions and entanglement of thermal states at high temperatures and discuss their applications to quantum information processing. We introduce thermal-state qubits and thermal-Bell states, which are a generalization of pure-state qubits and Bell states to thermal mixtures. A scheme is then presented to discriminate between the four thermal-Bell states without photon number resolving detection but with Kerr nonlinear interactions and two single-photon detectors. This enables one to perform quantum teleportation and gate operations for quantum computation with thermal-state qubits.