Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:2402.00479 · Physical review. D/Physical review. D.

Robustness of quantum correlation in quantum energy teleportation

Kazuki Ikeda, Adam Lowe

Published Nov 12, 2024• 9 citations
arXivHTMLPDF

Abstract

In this article, we explore a feedback-control protocol in different quantum field theories (QFTs) to study the quantum correlation in nonunitary evolution of quantum systems. Traditional studies on QFTs focus on quantum entanglement of pure states under the unitary evolution, however, we examine quantum correlation in mixed states using quantum energy teleportation (QET), which is an energy transfer protocol by utilizing ground state entanglement, and introduce quantum discord as a measure. QET involves a midcircuit measurement, which disrupts pure state entanglement. Despite this, our analysis demonstrates that quantum discord maintains the correlation throughout the QET process. We conducted numerical analyses with benchmark models including the Nambu-Jona-Lasinio (NJL) model, revealing that quantum discord consistently acts as an order parameter for phase transitions. The model is extended in a way that it has both the chiral chemical potential and the chemical potential, which are useful to study the phase structures mimicking the chiral imbalance between left- and right- quarks coupled to the chirality density operator. In all cases we studied, the quantum discord behaved as an order parameter of the phase transition. Published by the American Physical Society 2024

DOI
10.1103/physrevd.110.096010

Related papers

Quantum energy in quantum computers: insights from quantum energy teleportation

Kazuki Ikeda

Quantum energy teleportation (QET) is a quantum feedback protocol in which local measurements, classical communication, and preexisting entanglement enable the extraction of energy at a distant site, without transporting physical energy carriers. Originally conceived as a theoretical manifestation of Maxwell’s demon, QET has developed into a versatile tool for probing quantum correlations, diagnosing phase transitions, and powering emergent quantum thermodynamic technologies. This brief review provides a pedagogical introduction to the theoretical foundations and recent developments of QET, including quantum operations, entropic and fidelity-based bounds, and resource analyses involving quantum discord. Additionally, recent experimental realizations on superconducting quantum computers are revisited.

Canadian Journal of Physics•Jul 16, 2025•4 citations

Aspects of Quantum Energy Teleportation

Taisanul Haque

In this work, we explore quantum energy teleportation (QET) protocols, focusing on their behavior at finite temperatures , in ground and excited states. We analyze the role of entanglement as a resource for QET, particularly in thermal states, and compare the performance of QET across these initial states. We then introduce a method to extract ground-state energy through a protocol that employs only quantum measurements, local operations, and classical communication (LOCC), without requiring the ground state to be quantum correlated either through entanglement or quantum discord. To illustrate this, we propose a minimal model comprising two interacting qubits. These findings indicate that, in addition to the established QET framework where quantum correlation serves as a resource, it is possible to extract energy from an product ground state. This broadens the scope of QET's applicability across diverse quantum systems.

arXiv:2411.08927•Nov 12, 2024•0 citations

Quantum Correlations and Discord in Werner States for Quantum Teleportation

Saida M. Alkurkushi, Malek Nasser Ali Algabri, Ali Saif M. Hassan

Abstract Quantum teleportation fundamentally depends on shared quantum correlations between spatially separated parties. Although entanglement is widely recognized as the primary resource enabling teleportation, quantum discord represents a more general form of nonclassical correlations that can persist even when entanglement is absent. We provide a thorough analysis combining analytical and numerical evaluations of quantum discord, negativity, and concurrence across varying noise parameters. The study includes simulations under both ide-alized and realistic noisy conditions, incorporating depolarizing noise models alongside experimentally relevant constraints. To improve quantum fidelity and accurately characterize quantum correlations in noisy environments, advanced error mitigation techniques—such as measurement error correction and zero-noise extrapolation—are applied. In this study, we focus on teleportation protocols utilizing two-qubit Werner states, which constitute a significant class of noisy mixed states modeling imperfect entanglement. We systematically examine how the teleportation fidelity varies as a function of the Werner mixing parameter λ and investigate its relationship with the corresponding quantum discord. Our findings indicate that quantum discord remains strictly greater than zero even in parameter regions where entanglement vanishes, emphasizing the role of discord in sustaining quantum advantages in teleportation schemes exposed to noise and imperfections. This highlights the importance of considering non-entanglement quantum correlations for a comprehensive understanding of teleportation resources in realistic settings.

•Sep 9, 2025•0 citations

Quantum energy teleportation across a three-spin Ising chain in a Gibbs state

Jose Trevison, Masahiro Hotta

In general, it is important to identify what is the informational resource for quantum tasks. Quantum energy teleportation (QET) is a quantum task, which attains energy transfer in an operational sense by local operations and classical communication, and is expected to play a role in future development of nano-scale smart grids. We consider QET protocols in a three-element Ising spin system with non-periodic boundary conditions coupled to a thermal bath. The open chain is the minimal model of QET between two edge spins that allows the measurement and operation steps of the QET protocol to be optimized without restriction. It is possible to analyze how two-body correlations of the system, such as mutual information, entanglement and quantum discord, can be resources of this QET at each temperature. In particular, we stress that quantum discord is not the QET resource in some cases, even if arbitrary measurements and operations are available.

arXiv:1411.7495•Journal of Physics A Mathematical and Theoretical•Apr 7, 2015•23 citations

Quantum energy teleportation enabled by thermal discord

Michael R. Frey, Masahiro Hotta

Energy teleportation with no energy carrier between two physically separated sites was demonstrated in principle by M. Hotta in 2008. His demonstration used a three-step protocol applied to a Heisenberg spin particle pair initially in its fully entangled ground state. We apply the Hotta protocol to the same Heisenberg pair but now suppose the pair is, more generally, in a thermal state, introducing temperature as an explicit parameter. These thermal states show a degree of quantum correlation (thermal discord) at all temperatures. We find that at any temperature energy teleportation is possible with the Hotta protocol, even at temperatures beyond the threshold where the particles’ entanglement vanishes. This shows that entanglement is not fundamentally necessary for energy teleportation; quantum discord generally can suffice. It is also a new instance in which quantum dissonance (discord without entanglement) is seen to act as a quantum resource.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•May 28, 2013•1 citation

The relation between the quantum discord and quantum teleportation: The physical interpretation of the transition point between different quantum discord decay regimes

Katarzyna Roszak, Łukasz Cywiński

We study quantum teleportation via Bell-diagonal mixed states of two qubits in the context of the intrinsic properties of the quantum discord. We show that when the quantum-correlated state of the two qubits is used for quantum teleportation, the character of the teleportation efficiency changes substantially depending on the Bell-diagonal-state parameters, which can be seen when the worst-case-scenario or best-case-scenario fidelity is studied. Depending on the parameter range, one of two types of single-qubit states is hardest/easiest to teleport. The transition between these two parameter ranges coincides exactly with the transition between the range of classical correlation decay and quantum correlation decay characteristic for the evolution of the quantum discord. The correspondence provides a physical interpretation for the prominent feature of the decay of the quantum discord.

arXiv:1505.05741•Europhysics Letters (EPL)•Oct 1, 2015•13 citations
In this article, we explore a feedback-control protocol in different quantum field theories (QFTs) to study the quantum correlation in nonunitary evolution of quantum systems. Traditional studies on QFTs focus on quantum entanglement of pure states under the unitary evolution, however, we examine quantum correlation in mixed states using quantum energy teleportation (QET), which is an energy transfer protocol by utilizing ground state entanglement, and introduce quantum discord as a measure. QET involves a midcircuit measurement, which disrupts pure state entanglement. Despite this, our analysis demonstrates that quantum discord maintains the correlation throughout the QET process. We conducted numerical analyses with benchmark models including the Nambu-Jona-Lasinio (NJL) model, revealing that quantum discord consistently acts as an order parameter for phase transitions. The model is extended in a way that it has both the chiral chemical potential and the chemical potential, which are useful to study the phase structures mimicking the chiral imbalance between left- and right- quarks coupled to the chirality density operator. In all cases we studied, the quantum discord behaved as an order parameter of the phase transition. Published by the American Physical Society 2024
Quantum energy teleportation (QET) is a quantum feedback protocol in which local measurements, classical communication, and preexisting entanglement enable the extraction of energy at a distant site, without transporting physical energy carriers. Originally conceived as a theoretical manifestation of Maxwell’s demon, QET has developed into a versatile tool for probing quantum correlations, diagnosing phase transitions, and powering emergent quantum thermodynamic technologies. This brief review provides a pedagogical introduction to the theoretical foundations and recent developments of QET, including quantum operations, entropic and fidelity-based bounds, and resource analyses involving quantum discord. Additionally, recent experimental realizations on superconducting quantum computers are revisited.
In this work, we explore quantum energy teleportation (QET) protocols, focusing on their behavior at finite temperatures , in ground and excited states. We analyze the role of entanglement as a resource for QET, particularly in thermal states, and compare the performance of QET across these initial states. We then introduce a method to extract ground-state energy through a protocol that employs only quantum measurements, local operations, and classical communication (LOCC), without requiring the ground state to be quantum correlated either through entanglement or quantum discord. To illustrate this, we propose a minimal model comprising two interacting qubits. These findings indicate that, in addition to the established QET framework where quantum correlation serves as a resource, it is possible to extract energy from an product ground state. This broadens the scope of QET's applicability across diverse quantum systems.
Abstract Quantum teleportation fundamentally depends on shared quantum correlations between spatially separated parties. Although entanglement is widely recognized as the primary resource enabling teleportation, quantum discord represents a more general form of nonclassical correlations that can persist even when entanglement is absent. We provide a thorough analysis combining analytical and numerical evaluations of quantum discord, negativity, and concurrence across varying noise parameters. The study includes simulations under both ide-alized and realistic noisy conditions, incorporating depolarizing noise models alongside experimentally relevant constraints. To improve quantum fidelity and accurately characterize quantum correlations in noisy environments, advanced error mitigation techniques—such as measurement error correction and zero-noise extrapolation—are applied. In this study, we focus on teleportation protocols utilizing two-qubit Werner states, which constitute a significant class of noisy mixed states modeling imperfect entanglement. We systematically examine how the teleportation fidelity varies as a function of the Werner mixing parameter λ and investigate its relationship with the corresponding quantum discord. Our findings indicate that quantum discord remains strictly greater than zero even in parameter regions where entanglement vanishes, emphasizing the role of discord in sustaining quantum advantages in teleportation schemes exposed to noise and imperfections. This highlights the importance of considering non-entanglement quantum correlations for a comprehensive understanding of teleportation resources in realistic settings.
In general, it is important to identify what is the informational resource for quantum tasks. Quantum energy teleportation (QET) is a quantum task, which attains energy transfer in an operational sense by local operations and classical communication, and is expected to play a role in future development of nano-scale smart grids. We consider QET protocols in a three-element Ising spin system with non-periodic boundary conditions coupled to a thermal bath. The open chain is the minimal model of QET between two edge spins that allows the measurement and operation steps of the QET protocol to be optimized without restriction. It is possible to analyze how two-body correlations of the system, such as mutual information, entanglement and quantum discord, can be resources of this QET at each temperature. In particular, we stress that quantum discord is not the QET resource in some cases, even if arbitrary measurements and operations are available.
Energy teleportation with no energy carrier between two physically separated sites was demonstrated in principle by M. Hotta in 2008. His demonstration used a three-step protocol applied to a Heisenberg spin particle pair initially in its fully entangled ground state. We apply the Hotta protocol to the same Heisenberg pair but now suppose the pair is, more generally, in a thermal state, introducing temperature as an explicit parameter. These thermal states show a degree of quantum correlation (thermal discord) at all temperatures. We find that at any temperature energy teleportation is possible with the Hotta protocol, even at temperatures beyond the threshold where the particles’ entanglement vanishes. This shows that entanglement is not fundamentally necessary for energy teleportation; quantum discord generally can suffice. It is also a new instance in which quantum dissonance (discord without entanglement) is seen to act as a quantum resource.
We study quantum teleportation via Bell-diagonal mixed states of two qubits in the context of the intrinsic properties of the quantum discord. We show that when the quantum-correlated state of the two qubits is used for quantum teleportation, the character of the teleportation efficiency changes substantially depending on the Bell-diagonal-state parameters, which can be seen when the worst-case-scenario or best-case-scenario fidelity is studied. Depending on the parameter range, one of two types of single-qubit states is hardest/easiest to teleport. The transition between these two parameter ranges coincides exactly with the transition between the range of classical correlation decay and quantum correlation decay characteristic for the evolution of the quantum discord. The correspondence provides a physical interpretation for the prominent feature of the decay of the quantum discord.