Classical Half-Adder Using Trapped-Ion Quantum Bits: Toward Energy-Efficient Computation

Reversible computation has been proposed as a future paradigm for energy efficient computation, but so far few implementations have been realized in practice. Quantum circuits, running on quantum computers, are one construct known to be reversible. In this work, we provide a proof-of-principle of classical logical gates running on quantum technologies. In particular, we propose and realize experimentally, Toffoli and Half-Adder circuits suitable for classical computation, using radio frequency-controlled 171Yb+ ions in a macroscopic linear Paul-trap as qubits. We analyze the energy required to operate the logic gates, both theoretically and experimentally, with a focus on the control energy. We identify bottlenecks and possible improvements in future platforms for energetically efficient computation, e.g., trap chips with integrated antennas and cavity qed. Our experimentally verified energetic model also fills a gap in the literature of the energetics of quantum information and outlines the path for its detailed study, as well as its potential applications to classical computing.