The article explores the use of multi-qubit Rydberg gates to generate Schrödinger cat states of the Greenberger-Horne-Zeilinger (GHZ) type in an optical atomic clock. The authors demonstrate high-fidelity two-qubit entangling gates and use these to prepare GHZ states of up to 9 optical clock qubits. They perform an atom-laser frequency comparison using GHZ states, achieving a fractional frequency instability below the standard quantum limit (SQL) for up to 4 qubits. However, due to the reduced dynamic range of GHZ states, they fail to improve clock precision compared to unentangled atoms. To overcome this, they introduce a cascade of varying-size GHZ states to perform unambiguous phase estimation over an extended interval, demonstrating key building blocks for approaching Heisenberg-limited scaling of optical atomic clock precision. The results highlight the potential of GHZ states in quantum-enhanced metrology and the importance of extending the dynamic range of these states.The article explores the use of multi-qubit Rydberg gates to generate Schrödinger cat states of the Greenberger-Horne-Zeilinger (GHZ) type in an optical atomic clock. The authors demonstrate high-fidelity two-qubit entangling gates and use these to prepare GHZ states of up to 9 optical clock qubits. They perform an atom-laser frequency comparison using GHZ states, achieving a fractional frequency instability below the standard quantum limit (SQL) for up to 4 qubits. However, due to the reduced dynamic range of GHZ states, they fail to improve clock precision compared to unentangled atoms. To overcome this, they introduce a cascade of varying-size GHZ states to perform unambiguous phase estimation over an extended interval, demonstrating key building blocks for approaching Heisenberg-limited scaling of optical atomic clock precision. The results highlight the potential of GHZ states in quantum-enhanced metrology and the importance of extending the dynamic range of these states.