The paper by Y. Nakamura, Yu. A. Pashkin, and J. S. Tsai reports on the coherent control and observation of a quantum state in a single-Cooper-pair box, an artificial two-level system connected to a reservoir via a Josephson junction. Despite its macroscopic nature, the system exhibits coherent superposition of two charge states differing by $2e$. The authors apply short voltage pulses to modify the energies of these states, allowing for the coherent evolution of the quantum state. The state is probed using a tunneling current through an additional probe junction. The results demonstrate coherent operation and measurement of a single qubit in a solid-state electronic device, marking a significant step towards functional quantum circuit integration. The coherent oscillations are observed in the time domain, and the Josephson energy is estimated, providing insights into the decoherence mechanisms and potential applications in quantum computing.The paper by Y. Nakamura, Yu. A. Pashkin, and J. S. Tsai reports on the coherent control and observation of a quantum state in a single-Cooper-pair box, an artificial two-level system connected to a reservoir via a Josephson junction. Despite its macroscopic nature, the system exhibits coherent superposition of two charge states differing by $2e$. The authors apply short voltage pulses to modify the energies of these states, allowing for the coherent evolution of the quantum state. The state is probed using a tunneling current through an additional probe junction. The results demonstrate coherent operation and measurement of a single qubit in a solid-state electronic device, marking a significant step towards functional quantum circuit integration. The coherent oscillations are observed in the time domain, and the Josephson energy is estimated, providing insights into the decoherence mechanisms and potential applications in quantum computing.