[Paper Review] Experimental Activation of Strong Local Passive States with Quantum Information

Nayeli A. Rodríguez-Briones, Hemant Katiyar+2 more|arXiv (Cornell University)|Mar 30, 2022

Atomic and Subatomic Physics Research4 citations

TL;DR

This paper presents the first experimental realization of quantum energy teleportation (QET), demonstrating local activation of zero-point energy from a strong local passive (SLP) entangled ground state using nuclear magnetic resonance (NMR). By applying local operations and classical communication (LOCC), the protocol extracts energy from a system initially unable to yield energy locally, confirming theoretical predictions of energy activation via quantum correlations in multipartite systems.

ABSTRACT

Strong local passivity is a property of multipartite quantum systems from which it is impossible to extract energy locally. Surprisingly, if the strong local passive state displays entanglement, it could be possible to locally activate energy density by adding classical communication between different partitions of the system, through so-called "quantum energy teleportation" protocols. Here, we report both the first experimental observation of local activation of energy density on an entangled state and the first realization of a quantum energy teleportation protocol using nuclear magnetic resonance on a bipartite quantum system.

Motivation & Objective

• To experimentally demonstrate the activation of locally inaccessible energy in strong local passive (SLP) quantum states.
• To realize a quantum energy teleportation (QET) protocol in a controlled quantum system.
• To validate that entanglement enables local energy extraction without global energy transfer.
• To show feasibility of unitary QET protocols using nuclear magnetic resonance (NMR) techniques.
• To provide experimental evidence of zero-point energy density activation in an entangled ground state.

Proposed method

• The experiment uses a three-qubit NMR system in a pseudo-pure state prepared via spatial averaging, with the 4th qubit kept in a maximally mixed state.
• The Hamiltonian is decomposed into Zeeman (HZ) and spin-spin coupling (HJ) terms, with Jjk values set to simulate an interacting system.
• A fully unitary QET protocol is implemented by decomposing complex unitaries into single-qubit rotations and evolution under the natural Hamiltonian.
• Gate sequences are optimized using GRAPE pulses for single-qubit operations and time-delayed evolutions for multi-qubit interactions.
• Measurement of expectation values ⟨ZB⟩ and ⟨XAXB⟩ is performed via Ry(π/2) rotations to map non-observable terms into measurable ones.
• State tomography confirms a fidelity of 0.9996 for the pseudo-pure state, ensuring high-fidelity protocol execution.

Experimental results

Research questions

• RQ1 Can energy be locally activated from a strong local passive (SLP) state using quantum information protocols?
• RQ2 Is quantum energy teleportation (QET) experimentally realizable in a controlled quantum system?
• RQ3 Can entanglement enable local energy extraction without global energy transfer?
• RQ4 Does the QET protocol successfully extract zero-point energy density from an entangled ground state?
• RQ5 Can a fully unitary QET protocol be implemented and verified in an NMR system?

Key findings

• The experiment successfully demonstrated local energy extraction from a strong local passive state, confirming the theoretical prediction of energy activation via LOCC.
• The first experimental realization of a quantum energy teleportation (QET) protocol was achieved using a three-qubit NMR system.
• Energy was extracted beyond local and ambient noise, with no measurable energy transfer through the system, validating the protocol’s non-local nature.
• The fidelity of the prepared pseudo-pure state was measured at 0.9996, ensuring high-fidelity implementation of the QET protocol.
• The protocol achieved energy activation by using measurement outcomes to inform local unitary operations, demonstrating the role of quantum correlations in enabling otherwise inaccessible energy.
• The experimental results confirm that zero-point energy density can be activated in an entangled ground state under controlled conditions, marking a milestone in quantum thermodynamics.