# An Interaction-Free Quantum Measurement-Driven Engine

## TL;DR

This paper proposes a quantum engine based on interaction-free measurement, allowing the lifting of a quantum bomb using a photon without direct interaction, highlighting nonlocal energy exchange and contextuality.

## Contribution

It introduces a novel quantum engine utilizing interaction-free measurement principles, demonstrating energy transfer without direct interaction and exploring foundational quantum effects.

## Key findings

- The engine can lift a quantum bomb without explosion.
- Energy transfer occurs without absorption, implying nonlocal effects.
- Supports interpretation with weak value formalism and contextuality evidence.

## Abstract

Recently highly-efficient quantum engines were devised by exploiting the stochastic energy changes induced by quantum measurement. Here we show that such an engine can be based on an interaction-free measurement, in which the meter seemingly does not interact with the measured object. We use a modified version of the Elitzur-Vaidman bomb tester, an interferometric setup able to detect the presence of a bomb triggered by a single photon without exploding it. In our case, a quantum bomb subject to a gravitational force is initially in a superposition of being inside and outside one of the interferometer arms. We show that the bomb can be lifted without blowing up. This occurs when a photon traversing the interferometer is detected at a port that is always dark when the bomb is located outside the arm. The required potential energy is provided by the photon (which plays the role of the meter) even though it was not absorbed by the bomb. A natural interpretation is that the photon traveled through the arm which does not contain the bomb -- otherwise the bomb would have exploded -- but it implies the surprising conclusion that the energy exchange occurred at a distance despite a local interaction Hamiltonian. We use the weak value formalism to support this interpretation and find evidence of contextuality. Regardless of interpretation, this interaction-free quantum measurement engine is able to lift the most sensitive bomb without setting it off.