# Extracting work from quantum measurement in Maxwell demon engines

## TL;DR

This paper introduces a novel quantum Maxwell's demon engine that extracts work directly from measurement channels without needing a heat bath, and demonstrates that frequent measurements can eliminate memory erasure costs.

## Contribution

It proposes a new quantum engine model where work is extracted from measurements, reducing the role of heat baths and erasure costs in quantum thermodynamics.

## Key findings

- Work can be extracted directly from measurement channels.
- Frequent measurements in the Zeno regime eliminate memory erasure costs.
- The paradigm offers new insights into quantum heat engines.

## Abstract

The essence of both classical and quantum engines is to extract useful energy (work) from stochastic energy sources, e.g. thermal baths. In Maxwell's demon engines, work extraction is assisted by a feedback control based on measurements performed by a demon, whose memory is erased at some nonzero energy cost. Here we propose a new type of quantum Maxwell's demon engine where work is directly extracted from the measurement channel, such that no heat bath is required. We show that in the Zeno regime of frequent measurements, memory erasure costs eventually vanish. Our findings provide a new paradigm to analyze quantum heat engines and work extraction in the quantum world.