Powering Quantum Computation with Quantum Batteries

Abstract

Executing quantum logic in cryogenic quantum computers requires a continuous energy supply from room-temperature control electronics. This dependence on external energy sources creates scalability limitations due to control channel density and heat dissipation. Here, we propose quantum batteries (QBs) as intrinsic quantum energy sources for quantum computation, enabling the thermodynamic limit of zero dissipation for unitary gates. Unlike classical power sources, QBs maintain quantum coherence with their load - a property that, while theoretically studied, remains unexploited in practical quantum technologies. We demonstrate that initializing a bosonic QB in a Fock state can supply the energy required for arbitrary unitary gates regardless of the circuit's depth, via the recycling of pre-charged energy. Crucially, allowing QB-qubit entanglement during computation lowers the QB initial energy requirements below established energy-fidelity bounds. This scheme facilitates a universal gate set controlled by a single parameter per qubit, its resonant frequency. The relative detuning of each qubit from the QB resonant frequency gives rise to qualitatively two gate types, off-resonance and around-resonance. The former facilitates dispersive gates which allow multi-qubit parity probing while the latter enables energy exchange between the QB and the qubits, driving both population transfer and entanglement generation. This mechanism utilizes the all-to-all connectivity of the shared resonator architecture to go beyond the standard single- and two-qubit native gates of current platforms with multi-qubit gate timescales of few pi/g, where g is the qubit-resonator coupling. The resultant speed-up includes also superextensive gates between symmetric Dicke states, characteristic of QB systems.