Like quantum state teleportation, quantum energy teleportation (QET) can transmit energy through local operation and classical communication. This QET process even can extract energy from a strong local passive (SLP) state, from which any local operation can only inject energy. However, finding a SLP state is an important open question. In this paper, in the Hamiltonian of the minimal QET model, we obtain a set of SLP pure states by correlation matrix analysis. Our method is computable and easier to understand in certain Hamiltonians and states. Through the method of mathematic programming, we find an amazing phenomenon in which the energy teleportation efficiency can be greater than 1 and we reveal the essence of this phenomenon. It can be extended to the mixed state and spin chain model. Our result shows that quantum steering plays an important role in the QET protocol.
Like quantum state teleportation, quantum energy teleportation (QET) can transmit energy through local operation and classical communication. This QET process even can extract energy from a strong local passive (SLP) state, from which any local operation can only inject energy. However, finding a SLP state is an important open question. In this paper, in the Hamiltonian of the minimal QET model, we obtain a set of SLP pure states by correlation matrix analysis. Our method is computable and easier to understand in certain Hamiltonians and states. Through the method of mathematic programming, we find an amazing phenomenon in which the energy teleportation efficiency can be greater than 1 and we reveal the essence of this phenomenon. It can be extended to the mixed state and spin chain model. Our result shows that quantum steering plays an important role in the QET protocol.
Quantum energy teleportation (QET) is an energy extraction protocol via local operation and classical communication (LOCC). In this paper, we analyze QET with the correlation matrix and find the essence of QET is a quantum steering process. We propose an extended QET called strong QET protocol and define the QET passive state, which shows that quantum correlation is not a sufficient condition for QET. We also compare QET in noisy channels with direct energy extraction schemes, which indicates the advantage of our method in dealing with quantum operations. Furthermore, we extend the method to the N-qubit QET and give numerical examples.
Quantum energy teleportation (QET) has been proposed to overcome the restrictions of strong local passivity (SLP) and to facilitate energy transfer in quantum systems. Traditionally, QET has only been considered under strict constraints, including the requirements that the initial state be the ground state of an interacting Hamiltonian, that Alice's measurement commute with the interaction terms, and that entanglement be present. These constraints have significantly limited the broader applicability of QET protocols. In this work, we demonstrate that SLP can arise beyond these conventional constraints, establishing the necessity of QET in a wider range of scenarios for local energy extraction. This leads to a more flexible and generalized framework for QET. Furthermore, we introduce the concept of a "local effective Hamiltonian," which eliminates the need for optimization techniques in determining Bob's optimal energy extraction in QET protocols. As an additional advantage, the amount of energy that can be extracted using our new protocol is amplified to be 7.2 times higher than that of the original protocol. These advancements enhance our understanding of QET and extend its broader applications to quantum technologies. To support our findings, we implement the protocol on quantum hardware, confirming its theoretical validity and experimental feasibility.
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.
Quantum energy teleportation (QET) is a protocol that enables the extraction of positive energy from a local subsystem by exploiting ground-state entanglement and classical communication, without any physical carrier transporting energy between distant parties. In this work, we propose and analyze a QET protocol implemented in strongly driven atomic systems subjected to intense classical fields. We model a pair of interacting two-level atoms (or effective few-level systems) driven by a strong, time-dependent field and coupled via dipole–dipole or mediated interactions. The strong field creates a nontrivial, Floquet-engineered energy landscape and modifies the structure of ground-state and steady-state correlations. Within this setting, we construct local energy density operators and identify regimes in which negative local energy densities are dynamically generated and can be accessed via local measurements. We then formulate a QET protocol in which Alice performs a local measurement on her strongly driven atom, injects energy into the system, and sends the classical outcome to Bob, who performs a conditional local unitary on his distant atom to extract positive energy from the strongly driven environment. We derive explicit expressions for the teleported energy and analyze its dependence on driving strength, detuning, atom–atom coupling, and measurement parameters. Our results demonstrate that strong-field driving can enhance the amount of teleported power , extend the QET operating range to non-equilibrium Floquet regimes, and provide a feasible route toward realizing QET in tabletop atomic platforms driven by intense laser fields.
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.
Many-body quantum systems in the ground states have zero-point energy due to the uncertainty relation. In many cases, the system in the ground state accompanies spatially entangled energy density fluctuation via the noncommutativity of the energy density operators, though the total energy takes a fixed value, i.e., the lowest eigenvalue of the Hamiltonian. Quantum energy teleportation (QET) is a protocol for the extraction of the zero-point energy out of one subsystem using information of a remote measurement of another subsystem. From an operational viewpoint of protocol users, QET can be regarded as an effective rapid energy transportation without breaking all physical laws, including causality and local energy conservation. In the protocol, the ground-state entanglement plays a crucial role. In this paper, we show analytically for a general class of spin-chain systems that the entanglement entropy is lower bounded by a positive quadratic function of the teleported energy between the regions of a QET protocol. This supports a general conjecture that ground-state entanglement is an evident physical resource for energy transportation in the context of QET. The result may also deepen our understanding of the energy density fluctuation in condensed-matter systems from a perspective of quantum information theory.