The quantum-energy-teleportation cell

Why the library suggests it

Masahiro Hotta's protocol moves energy out of a patch of field that has none, using a measurement here, a classical message, and a conditioned operation there (Quantum measurement information as a key to energy extraction from local vacuums, 2008). Kazuki Ikeda ran it on six IBM machines, one of them free to the public, and measured the local energy going below the ground-state level (Demonstration of Quantum Energy Teleportation on Superconducting Quantum Hardware, 2023). Nayeli Rodríguez-Briones and colleagues did it on three carbon nuclei in a crotonic-acid molecule in fourteen milliseconds, far faster than energy could have crossed the molecule (Experimental Activation of Strong Local Passive States with Quantum Information, 2023). The exact boundary of what purely local operations can do — and the fact that classical messages reopen the door — is drawn in Fundamental Limitations to Local Energy Extraction in Quantum Systems (2019), and the distance limit that kept the protocol millimetre-scale is removed by putting squeezed vacuum in the gap (Quantum energy teleportation without a limit of distance, 2014).

The experiment or build

Start on a public quantum computer: the circuit is six gates deep and free to run. Then build the physical version — a chain of superconducting qubits, or the nuclear magnetic resonance version on a benchtop spectrometer — and turn it into an engineering question rather than a demonstration: put many cells in parallel, measure the energy delivered per cell, and measure the total energy spent on measurement, control and the classical channel. The settling measurement is the ratio of energy delivered at the receiving end to total energy spent across the whole apparatus, as a function of the number of cells. Nobody expects that ratio to pass one; what nobody has published is how it scales, and the scaling is the entire engineering question. A companion result shows the same protocol run in reverse puts more energy into one cell of a quantum battery than the classical share allows (Exceeding the maximum classical energy density in fully charged quantum batteries, 2025), which is the storage half of the same architecture.