Ground-State Cooling of a Trapped Ion Using Long-Wavelength Radiation.

Area of Science:

• Quantum physics
• Atomic physics
• Quantum information science

Background:

• Trapped ions are crucial for quantum computing and simulations.
• Cooling ions to their ground state is essential for high-fidelity quantum operations.
• Traditional cooling methods often rely on lasers, which can be complex and costly.

Purpose of the Study:

• To demonstrate ground-state cooling of a trapped ion using radio-frequency (rf) radiation.
• To explore rf radiation as an alternative to lasers for motional quantum state engineering.
• To accurately measure motional heating rates after ground-state cooling.

Main Methods:

• Ground-state cooling of a trapped ion was achieved using rf radiation.
• Sideband cooling techniques were employed to reach the vibrational ground state.
• Rabi oscillations between Fock states |n=0⟩ and |n=1⟩ were driven to demonstrate motional state engineering.
• Motional heating rates were measured with high precision.

Main Results:

• A mean phonon number of n[over ¯]=0.13(4) was measured after sideband cooling.
• This corresponds to a ground-state occupation probability of 88(7)%.
• A reduction in motional heating rate by almost 2 orders of magnitude was achieved.

Conclusions:

• Radio-frequency radiation is a viable and powerful tool for ground-state cooling and motional quantum state engineering in trapped ions.
• Eliminating electrical noise sources is critical for minimizing motional heating rates.
• This technique offers a promising alternative to laser cooling for quantum applications.