Italian physicists have proposed a new concept of a quantum battery based on entangled qubits that can be implemented using existing technologies. They hope to create a five-qubit prototype within three years. An article with the results was published in the journal Physical Review Letters.
A few years ago, physicists proposed the theoretical idea of a quantum battery that would store energy not in the form of chemical compounds, but thanks to the excited states of quantum objects. Most of these papers have been written by researchers in quantum information theory who are interested in fundamental theorems about the limits of energy storage and transfer. In a new work, physicists have proposed a scheme that can be implemented in practice.
Italian physicists have proposed using superconducting circuits or semiconductor quantum dots as qubits. In the simplest version considered by the authors, they must have two energy levels - ground and excited. All qubits are placed in a common optical resonator, where they can be simultaneously transferred to an excited state and entangled by one action, for example, a laser pulse of a certain energy. As a result, according to scientists, the power with which you can charge the battery increases in proportion to the square root of the qubits. At the same time, for a battery of a qubit array in individual resonators, this value does not change when new elements are added.
The authors note that the proposed system does not violate any thermodynamic laws, since it uses a more intense flow of energy from the source to the battery than is acceptable for other devices. Physicists also note that such devices will not replace modern batteries. Despite the close to theoretical charging speed, they will also discharge extremely quickly - on the nanosecond scale. In addition, compared to chemical elements, they have a tiny capacity: the typical energy difference between the levels of a qubit is 0.001 electron volts, while modern laptop batteries store about 1024 eV. Therefore, the main field of application for such batteries can be the field of quantum computing. In this case, the battery inside the quantum computer will run in a cycle:each qubit will be charged while the computer takes energy from the next one to perform calculations.
Nikolay Khizhnyak